Biology, ecology, distribution and control of the invasive weed, lactuca serriola l. (wild lettuce) : a global review
- Chadha, Aakansha, Florentine, Singarayer
- Authors: Chadha, Aakansha , Florentine, Singarayer
- Date: 2021
- Type: Text , Journal article , Review
- Relation: Plants Vol. 10, no. 10 (2021), p.
- Full Text:
- Reviewed:
- Description: Lactuca serriola L. (wild lettuce) is a highly invasive C3 weed in many countries, including Australia, Canada, and the USA. This weed is a severe threat to agricultural systems, especially in crops grown with reduced or no‐tillage approaches, which commonly include wheat, cereals and pulses. Owing to the vertical orientation of its leaves in the north‐south plane and its root architec-ture, L. serriola can maintain high water use efficiency under drought conditions, giving it the ability to expand its range under a drying climate. Each plant can produce up to 100,000 seeds which have no primary dormancy and form a short‐term seedbank lasting up to three years. Most seedlings emerge in autumn and overwinter as a rosette, with a small flush of emergence in spring depicting staggered germination. Research into control methods for this weed has been performed, and these methods include chemical herbicides applied alone and in combination, the establishment of plant competition, tillage, mowing and bioherbicide. Herbicides can provide effective control when applied in the seedling or rosette stage; however, spring germination is difficult to control, as it skips the rosette stage. Some biotypes are now resistant to ALS inhibitor and synthetic auxins, causing concern regarding using herbicides. A dedicated integrated management plan for 3–4 years is recommended for the control of this troublesome species. This review will explore the biology, ecology, distribution, current control techniques and previous research on this weed, allowing us to make recommendations for its future research and management. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
- Authors: Chadha, Aakansha , Florentine, Singarayer
- Date: 2021
- Type: Text , Journal article , Review
- Relation: Plants Vol. 10, no. 10 (2021), p.
- Full Text:
- Reviewed:
- Description: Lactuca serriola L. (wild lettuce) is a highly invasive C3 weed in many countries, including Australia, Canada, and the USA. This weed is a severe threat to agricultural systems, especially in crops grown with reduced or no‐tillage approaches, which commonly include wheat, cereals and pulses. Owing to the vertical orientation of its leaves in the north‐south plane and its root architec-ture, L. serriola can maintain high water use efficiency under drought conditions, giving it the ability to expand its range under a drying climate. Each plant can produce up to 100,000 seeds which have no primary dormancy and form a short‐term seedbank lasting up to three years. Most seedlings emerge in autumn and overwinter as a rosette, with a small flush of emergence in spring depicting staggered germination. Research into control methods for this weed has been performed, and these methods include chemical herbicides applied alone and in combination, the establishment of plant competition, tillage, mowing and bioherbicide. Herbicides can provide effective control when applied in the seedling or rosette stage; however, spring germination is difficult to control, as it skips the rosette stage. Some biotypes are now resistant to ALS inhibitor and synthetic auxins, causing concern regarding using herbicides. A dedicated integrated management plan for 3–4 years is recommended for the control of this troublesome species. This review will explore the biology, ecology, distribution, current control techniques and previous research on this weed, allowing us to make recommendations for its future research and management. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Can optimum solar radiation exposure or supplemented vitamin D intake reduce the severity of COVID-19 symptoms?
- Abraham, Joji, Dowling, Kim, Florentine, Singarayer
- Authors: Abraham, Joji , Dowling, Kim , Florentine, Singarayer
- Date: 2021
- Type: Text , Journal article , Review
- Relation: International Journal of Environmental Research and Public Health Vol. 18, no. 2 (2021), p. 1-21
- Full Text:
- Reviewed:
- Description: The foremost mortality-causing symptom associated with COVID-19 is acute respiratory distress syndrome (ARDS). A significant correlation has been identified between the deficiency in vitamin D and the risk of developing ARDS. It has been suggested that if we can reduce or modify ARDS in COVID-19 patients, we may significantly reduce the severity of COVID-19 symptoms and associated mortality rates. The increased mortality of dark-skinned people, who have a reduced UV absorption capacity, may be consistent with diminished vitamin D status. The factors associated with COVID-19 mortality, such as old age, ethnicity, obesity, hypertension, cardiovascular diseases, and diabetes, are all found to be linked with vitamin D deficiency. Based on this review and as a precautionary measure, it is suggested that the adoption of appropriate and safe solar exposure and vitamin D enriched foods and supplements should be considered to reduce the possible severity of COVID-19 symptoms. Safe sun exposure is deemed beneficial globally, specifically in low and middle- income countries, as there is no cost involved. It is also noted that improved solar exposure and vitamin D levels can reduce the impact of other diseases as well, thus assisting in maintaining general human well-being. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
- Authors: Abraham, Joji , Dowling, Kim , Florentine, Singarayer
- Date: 2021
- Type: Text , Journal article , Review
- Relation: International Journal of Environmental Research and Public Health Vol. 18, no. 2 (2021), p. 1-21
- Full Text:
- Reviewed:
- Description: The foremost mortality-causing symptom associated with COVID-19 is acute respiratory distress syndrome (ARDS). A significant correlation has been identified between the deficiency in vitamin D and the risk of developing ARDS. It has been suggested that if we can reduce or modify ARDS in COVID-19 patients, we may significantly reduce the severity of COVID-19 symptoms and associated mortality rates. The increased mortality of dark-skinned people, who have a reduced UV absorption capacity, may be consistent with diminished vitamin D status. The factors associated with COVID-19 mortality, such as old age, ethnicity, obesity, hypertension, cardiovascular diseases, and diabetes, are all found to be linked with vitamin D deficiency. Based on this review and as a precautionary measure, it is suggested that the adoption of appropriate and safe solar exposure and vitamin D enriched foods and supplements should be considered to reduce the possible severity of COVID-19 symptoms. Safe sun exposure is deemed beneficial globally, specifically in low and middle- income countries, as there is no cost involved. It is also noted that improved solar exposure and vitamin D levels can reduce the impact of other diseases as well, thus assisting in maintaining general human well-being. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Does climate play any role in covid-19 spreading? : an Australian perspective
- Abraham, Joji, Turville, Christopher, Dowling, Kim, Florentine, Singarayer
- Authors: Abraham, Joji , Turville, Christopher , Dowling, Kim , Florentine, Singarayer
- Date: 2021
- Type: Text , Journal article
- Relation: International Journal of Environmental Research and Public Health Vol. 18, no. 17 (2021), p.
- Full Text:
- Reviewed:
- Description: Compared to other countries, the COVID-19 pandemic did not severely affect Australia as measured by total deaths until mid-2021. Though a substantial number of daily confirmed cases (up to 698) were reported during the second wave, most of them were from the southern state of Victoria. This study examined the possible correlations between climate variables and the number of daily confirmed COVID-19 cases in Victoria, Australia, from 25 January to 31 October 2020. Appropriate regression models and cross-correlation diagnostics were used to examine the effect of temperature, rainfall, solar exposure, and ultraviolet index (UVI) with the number of daily confirmed cases. Significant positive associations were identified for solar exposure and maximum and average UVI for confirmed cases one and 19 days later. Negative associations for these variables were found for confirmed cases five days later. Minimum temperature had a significant negative correlation one day later and a positive effect 21 days later. No significant correlation was found for maximum temperature and rainfall. The most significant relationships were found for confirmed cases 19 days after changes in the meteorological variables. A 1% increase in solar exposure, maximum UVI, and average UVI was associated with a 0.31% (95% CI: 0.13 to 0.51), 0.71% (95% CI: 0.43 to 0.98), and 0.63% (95%CI: 0.20 to 1.61) increase 19 days later in the number of confirmed cases, respectively. The implications of these results can be used in the public health management of any possible future events in Australia. It also highlights the significance of considering the climatic variables and seasonality in all kinds of epidemics and pandemics. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
- Authors: Abraham, Joji , Turville, Christopher , Dowling, Kim , Florentine, Singarayer
- Date: 2021
- Type: Text , Journal article
- Relation: International Journal of Environmental Research and Public Health Vol. 18, no. 17 (2021), p.
- Full Text:
- Reviewed:
- Description: Compared to other countries, the COVID-19 pandemic did not severely affect Australia as measured by total deaths until mid-2021. Though a substantial number of daily confirmed cases (up to 698) were reported during the second wave, most of them were from the southern state of Victoria. This study examined the possible correlations between climate variables and the number of daily confirmed COVID-19 cases in Victoria, Australia, from 25 January to 31 October 2020. Appropriate regression models and cross-correlation diagnostics were used to examine the effect of temperature, rainfall, solar exposure, and ultraviolet index (UVI) with the number of daily confirmed cases. Significant positive associations were identified for solar exposure and maximum and average UVI for confirmed cases one and 19 days later. Negative associations for these variables were found for confirmed cases five days later. Minimum temperature had a significant negative correlation one day later and a positive effect 21 days later. No significant correlation was found for maximum temperature and rainfall. The most significant relationships were found for confirmed cases 19 days after changes in the meteorological variables. A 1% increase in solar exposure, maximum UVI, and average UVI was associated with a 0.31% (95% CI: 0.13 to 0.51), 0.71% (95% CI: 0.43 to 0.98), and 0.63% (95%CI: 0.20 to 1.61) increase 19 days later in the number of confirmed cases, respectively. The implications of these results can be used in the public health management of any possible future events in Australia. It also highlights the significance of considering the climatic variables and seasonality in all kinds of epidemics and pandemics. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Licorice (glycyrrhiza glabra) extracts-suitable pharmacological interventions for covid-19? a review
- Abraham, Joji, Florentine, Singarayer
- Authors: Abraham, Joji , Florentine, Singarayer
- Date: 2021
- Type: Text , Journal article , Review
- Relation: Plants Vol. 10, no. 12 (2021), p.
- Full Text:
- Reviewed:
- Description: Even though vaccination has started against COVID-19, people should continue maintaining personal and social caution as it takes months or years to get everyone vaccinated, and we are not sure how long the vaccine remains efficacious. In order to contribute to the mitigation of COVID-19 symptoms, the pharmaceutical industry aims to develop antiviral drugs to inhibit the SARS-CoV-2 replication and produce anti-inflammatory medications that will inhibit the acute respiratory distress syndrome (ARDS), which is the primary cause of mortality among the COVID-19 patients. In reference to these tasks, this article considers the properties of a medicinal plant named licorice (Glycyrrhiza glabra), whose phytochemicals have shown both antiviral and anti-inflammatory tendencies through previous studies. All the literature was selected through extensive search in various databases such as google scholar, Scopus, the Web of Science, and PubMed. In addition to the antiviral and anti-inflammatory properties, one of the licorice components has an autophagy-enhancing mechanism that studies have suggested to be necessary for COVID-19 treatment. Based on reviewing relevant professional and historical literature regarding the medicinal properties of licorice, it is suggested that it may be worthwhile to conduct in vitro and in vivo studies, including clinical trials with glycyrrhizic and glycyrrhetinic acids together with other flavonoids found in licorice, as there is the potentiality to provide natural interventions against COVID-19 symptoms. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Licorice (glycyrrhiza glabra) extracts-suitable pharmacological interventions for covid-19? a review
- Authors: Abraham, Joji , Florentine, Singarayer
- Date: 2021
- Type: Text , Journal article , Review
- Relation: Plants Vol. 10, no. 12 (2021), p.
- Full Text:
- Reviewed:
- Description: Even though vaccination has started against COVID-19, people should continue maintaining personal and social caution as it takes months or years to get everyone vaccinated, and we are not sure how long the vaccine remains efficacious. In order to contribute to the mitigation of COVID-19 symptoms, the pharmaceutical industry aims to develop antiviral drugs to inhibit the SARS-CoV-2 replication and produce anti-inflammatory medications that will inhibit the acute respiratory distress syndrome (ARDS), which is the primary cause of mortality among the COVID-19 patients. In reference to these tasks, this article considers the properties of a medicinal plant named licorice (Glycyrrhiza glabra), whose phytochemicals have shown both antiviral and anti-inflammatory tendencies through previous studies. All the literature was selected through extensive search in various databases such as google scholar, Scopus, the Web of Science, and PubMed. In addition to the antiviral and anti-inflammatory properties, one of the licorice components has an autophagy-enhancing mechanism that studies have suggested to be necessary for COVID-19 treatment. Based on reviewing relevant professional and historical literature regarding the medicinal properties of licorice, it is suggested that it may be worthwhile to conduct in vitro and in vivo studies, including clinical trials with glycyrrhizic and glycyrrhetinic acids together with other flavonoids found in licorice, as there is the potentiality to provide natural interventions against COVID-19 symptoms. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Medicinal value of three agricultural weed species of the asteraceae family : a review
- Jayasundera, Mithila, Florentine, Singarayer, Tennakoon, Kushan, Chauhan, Bhagirath
- Authors: Jayasundera, Mithila , Florentine, Singarayer , Tennakoon, Kushan , Chauhan, Bhagirath
- Date: 2021
- Type: Text , Journal article , Review
- Relation: Pharmacognosy Journal Vol. 13, no. 1 (2021), p. 264-277
- Full Text:
- Reviewed:
- Description: Ageratum conyzoides L., Tridax procumbens L. and Bidens pilosa L. are well known plant species of the Asteraceae family that are considered weeds in intensive agriculture. These weeds are traditionally known to have medicinal properties and have been used for therapeutic treatments. However, it is only the lack of proper knowledge, awareness and screening that have limited their use in pharmaceutical sectors. This review attempts to consolidate the traditional, phytochemical and pharmacological studies that have been carried out on Ageratum conyzoides L., Tridax procumbens L. and Bidens pilosa L., which we note are widely spread throughout the world. This study was conducted through a coherent search on Ageratum conyzoides L., Tridax procumbens L. and Bidens pilosa L. with respect to traditional uses, phytochemical and pharmacological studies that have been performed on these three agricultural weeds all over the world. An exploration of reported descriptions of the potential medical importance of three agricultural weed species (A. conyzoides, T. procumbens and B. pilosa) has been presented. The present review would encourage further clinical investigations into these three plants and their extracts to more closely define the range of uses of these herbs for clinical applications. This, in turn, would give a clear understanding whether these weed species might be targeted to be conserved in a sustainable manner rather than eradicated. © 2021 Phcogj.Com. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license.
- Authors: Jayasundera, Mithila , Florentine, Singarayer , Tennakoon, Kushan , Chauhan, Bhagirath
- Date: 2021
- Type: Text , Journal article , Review
- Relation: Pharmacognosy Journal Vol. 13, no. 1 (2021), p. 264-277
- Full Text:
- Reviewed:
- Description: Ageratum conyzoides L., Tridax procumbens L. and Bidens pilosa L. are well known plant species of the Asteraceae family that are considered weeds in intensive agriculture. These weeds are traditionally known to have medicinal properties and have been used for therapeutic treatments. However, it is only the lack of proper knowledge, awareness and screening that have limited their use in pharmaceutical sectors. This review attempts to consolidate the traditional, phytochemical and pharmacological studies that have been carried out on Ageratum conyzoides L., Tridax procumbens L. and Bidens pilosa L., which we note are widely spread throughout the world. This study was conducted through a coherent search on Ageratum conyzoides L., Tridax procumbens L. and Bidens pilosa L. with respect to traditional uses, phytochemical and pharmacological studies that have been performed on these three agricultural weeds all over the world. An exploration of reported descriptions of the potential medical importance of three agricultural weed species (A. conyzoides, T. procumbens and B. pilosa) has been presented. The present review would encourage further clinical investigations into these three plants and their extracts to more closely define the range of uses of these herbs for clinical applications. This, in turn, would give a clear understanding whether these weed species might be targeted to be conserved in a sustainable manner rather than eradicated. © 2021 Phcogj.Com. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license.
Response of glyphosate-resistant and glyphosate-susceptible biotypes of annual sowthistle (Sonchus oleraceus) to increased carbon dioxide and variable soil moisture
- Mobli, Ahmadreza, Florentine, Singarayer, Jha, Prashant, Chauhan, Bhagirath
- Authors: Mobli, Ahmadreza , Florentine, Singarayer , Jha, Prashant , Chauhan, Bhagirath
- Date: 2020
- Type: Text , Journal article
- Relation: Weed Science Vol. 68, no. 6 (2020), p. 575-581
- Full Text:
- Reviewed:
- Description: The growth response of annual sowthistle (Sonchus oleraceus L.) to anticipated future climate conditions is currently unknown, and thus two parallel studies were conducted dealing with glyphosate-resistant (GR) and glyphosate-susceptible (GS) biotypes of S. oleraceus. The glyphosate efficacy study was conducted using different doses of glyphosate (0 [control], 180, 360, 720 [recommended dose], and 1,440 g ae ha-1) at two different moisture levels (well-watered and water-stressed conditions). In the second study, the growth and seed production of these biotypes were studied under different atmospheric carbon dioxide (CO2) concentrations (450 and 750 ppm) and under well-watered (100% field capacity) and water-stressed (50% field capacity) conditions. Results showed that the GR biotype survived (>68%) at 1,440 g ha-1, but for the GS biotype, no plant survived, and both biotypes were slightly (<10%) affected by moisture regimes. In the elevated CO2 condition, the GS biotype plants were >38% taller and produced >44%, >18%, and >21% more leaves, buds, and seeds, respectively, compared with the ambient CO2 concentration under both moisture regimes. The biomass also increased by 27% in comparison with the ambient CO2 concentration. For the GR biotype, plants at the elevated CO2 level, while they also grew 38% taller in comparison with the ambient CO2 concentration, the numbers of leaves, buds, and seeds and biomass were not affected by this increase in CO2. Results showed that there were minimal changes in response to glyphosate for GR and GS biotypes of S. oleraceus with or without moisture stress. Our study suggests that future climate change with elevated CO2 levels can affect the response of S. oleraceus to glyphosate, and such knowledge will be helpful for weed management in the future. © 2020 Weed Science Society of America.
- Authors: Mobli, Ahmadreza , Florentine, Singarayer , Jha, Prashant , Chauhan, Bhagirath
- Date: 2020
- Type: Text , Journal article
- Relation: Weed Science Vol. 68, no. 6 (2020), p. 575-581
- Full Text:
- Reviewed:
- Description: The growth response of annual sowthistle (Sonchus oleraceus L.) to anticipated future climate conditions is currently unknown, and thus two parallel studies were conducted dealing with glyphosate-resistant (GR) and glyphosate-susceptible (GS) biotypes of S. oleraceus. The glyphosate efficacy study was conducted using different doses of glyphosate (0 [control], 180, 360, 720 [recommended dose], and 1,440 g ae ha-1) at two different moisture levels (well-watered and water-stressed conditions). In the second study, the growth and seed production of these biotypes were studied under different atmospheric carbon dioxide (CO2) concentrations (450 and 750 ppm) and under well-watered (100% field capacity) and water-stressed (50% field capacity) conditions. Results showed that the GR biotype survived (>68%) at 1,440 g ha-1, but for the GS biotype, no plant survived, and both biotypes were slightly (<10%) affected by moisture regimes. In the elevated CO2 condition, the GS biotype plants were >38% taller and produced >44%, >18%, and >21% more leaves, buds, and seeds, respectively, compared with the ambient CO2 concentration under both moisture regimes. The biomass also increased by 27% in comparison with the ambient CO2 concentration. For the GR biotype, plants at the elevated CO2 level, while they also grew 38% taller in comparison with the ambient CO2 concentration, the numbers of leaves, buds, and seeds and biomass were not affected by this increase in CO2. Results showed that there were minimal changes in response to glyphosate for GR and GS biotypes of S. oleraceus with or without moisture stress. Our study suggests that future climate change with elevated CO2 levels can affect the response of S. oleraceus to glyphosate, and such knowledge will be helpful for weed management in the future. © 2020 Weed Science Society of America.
Annual ryegrass (Lolium rigidum Gaud) competition altered wheat grain quality : A study under elevated atmospheric CO2 levels and drought conditions
- Fernando, Nimesha, Florentine, Singarayer, Naiker, Mani, Panozzo, Joe, Chauhan, Bhagirath
- Authors: Fernando, Nimesha , Florentine, Singarayer , Naiker, Mani , Panozzo, Joe , Chauhan, Bhagirath
- Date: 2019
- Type: Text , Journal article
- Relation: Food Chemistry Vol. 276, no. (2019), p. 285-290
- Full Text:
- Reviewed:
- Description: Annual ryegrass is one of the most serious, costly weeds of winter cropping systems in Australia. To determine whether its competition-mediated plant defence mechanisms effect on wheat grain quality, wheat (cv. Yitpi) and annual ryegrass were grown under two levels of CO2 (400 ppm; (a[CO2]) vs 700 ppm; (e[CO2]), two levels of water (well-watered vs drought) and two types of competition (wheat only; (W), and wheatxannual ryegrass; (W x R) with four replicates. The competitionx[CO2] interaction had a significant effect on wheat grain protein content, where it was increased in W x R under both e[CO2] (+ 17%) and a[CO2] (+ 21%). Grain yield, total grain reducing power and phenolic content were significantly affected by [CO2] x drought x competition. In a summary, annual ryegrass competition significantly altered the wheat grain quality under both [CO2] levels (depending on the soil water level), while also decreasing the grain yield.
- Authors: Fernando, Nimesha , Florentine, Singarayer , Naiker, Mani , Panozzo, Joe , Chauhan, Bhagirath
- Date: 2019
- Type: Text , Journal article
- Relation: Food Chemistry Vol. 276, no. (2019), p. 285-290
- Full Text:
- Reviewed:
- Description: Annual ryegrass is one of the most serious, costly weeds of winter cropping systems in Australia. To determine whether its competition-mediated plant defence mechanisms effect on wheat grain quality, wheat (cv. Yitpi) and annual ryegrass were grown under two levels of CO2 (400 ppm; (a[CO2]) vs 700 ppm; (e[CO2]), two levels of water (well-watered vs drought) and two types of competition (wheat only; (W), and wheatxannual ryegrass; (W x R) with four replicates. The competitionx[CO2] interaction had a significant effect on wheat grain protein content, where it was increased in W x R under both e[CO2] (+ 17%) and a[CO2] (+ 21%). Grain yield, total grain reducing power and phenolic content were significantly affected by [CO2] x drought x competition. In a summary, annual ryegrass competition significantly altered the wheat grain quality under both [CO2] levels (depending on the soil water level), while also decreasing the grain yield.
Atmospheric CO₂ Concentration and Other Limiting Factors in the Growth of C₃ and C₄ Plants
- Boretti, Albert, Florentine, Singarayer
- Authors: Boretti, Albert , Florentine, Singarayer
- Date: 2019
- Type: Text , Journal article
- Relation: Plants Vol. 8, no. 4 (2019), p. 1-11
- Full Text:
- Reviewed:
- Description: It has been widely observed that recent increases in atmospheric CO2 concentrations have had, so far, a positive effect on the growth of plants. This is not surprising since CO2 is an important nutrient for plant matter, being directly involved in photosynthesis. However, it is also known that the conditions which have accompanied this increase in atmospheric CO2 concentration have also had significant effects on other environmental factors. It is possible that these other effects may emerge as limiting factors which could act to prevent plant growth. This may involve complex interactions between prevailing sunlight and water conditions, variable temperatures, the availability of essential nutrients and the type of synthetic pathway for the plant species. The issue of concern to this investigation is if we should be worried about a possible shift in the C3-C4 paradigm driven by changes in the atmospheric CO2 concentration, or if some other factor, such as water scarcity, is much more relevant within a 30-year time frame. If an opinion is needed on what will have the worst effect on the survival of the planet between the scarcity of water or the reduced efficiency of C3 plants to sequester CO2, the issue of water is the more incisive.
- Authors: Boretti, Albert , Florentine, Singarayer
- Date: 2019
- Type: Text , Journal article
- Relation: Plants Vol. 8, no. 4 (2019), p. 1-11
- Full Text:
- Reviewed:
- Description: It has been widely observed that recent increases in atmospheric CO2 concentrations have had, so far, a positive effect on the growth of plants. This is not surprising since CO2 is an important nutrient for plant matter, being directly involved in photosynthesis. However, it is also known that the conditions which have accompanied this increase in atmospheric CO2 concentration have also had significant effects on other environmental factors. It is possible that these other effects may emerge as limiting factors which could act to prevent plant growth. This may involve complex interactions between prevailing sunlight and water conditions, variable temperatures, the availability of essential nutrients and the type of synthetic pathway for the plant species. The issue of concern to this investigation is if we should be worried about a possible shift in the C3-C4 paradigm driven by changes in the atmospheric CO2 concentration, or if some other factor, such as water scarcity, is much more relevant within a 30-year time frame. If an opinion is needed on what will have the worst effect on the survival of the planet between the scarcity of water or the reduced efficiency of C3 plants to sequester CO2, the issue of water is the more incisive.
Cultivation of low tetrahydrocannabinol (THC) Cannabis sativa L. cultivation in Victoria, Australia: Do we know enough?
- Humphries, Talia, Florentine, Singarayer
- Authors: Humphries, Talia , Florentine, Singarayer
- Date: 2019
- Type: Text , Journal article
- Relation: Australian Journal of Crop Science Vol. 13, no. 6 (2019), p. 911-919
- Full Text:
- Reviewed:
- Description: Late 2017, the ban on the cultivation and consumption of low tetrahydrocannabinol (THC) Cannabis sativa L. in Victoria, was lifted by the Federal Government of Australia. Its legalization presents the opportunity for Victoria to become a leading producer and distributer of these economically valuable hemp products. However, as a novel crop to Victoria, there is little information available for obtaining economically viable yields. Therefore, the objectives of this review were to firstly, develop an understanding of the environmental requirements shared by C. sativa cultivars, and what conditions promote fibre and grain yields. Secondly, it seeks to identify what farming practices have been conducted throughout Europe, Canada and China, and to explore whether these practices could be adapted to Victoria. Thirdly, the review will assist in making recommendations regarding which cultivars would be 'potential' candidates for commencing trials under Victorian climates so to find out the varieties that can provide high yields for fibre, grain and dual-purpose production. This review notes that Victoria shares a similar climate to central Europe, and has an ideal climate for the development of a successful hemp industry, as it has suitable lengths of daylight throughout spring and summer months and meets the precipitation requirements. This review has thus strongly suggested that the properties and attributes of European varieties of C. sativa should be further researched for site-specific cultivation in Victoria for fibre, grain and dual-purpose production in order to maximise harvest yields. © 2007-2019 Southern Cross Publishing-Australia.
- Authors: Humphries, Talia , Florentine, Singarayer
- Date: 2019
- Type: Text , Journal article
- Relation: Australian Journal of Crop Science Vol. 13, no. 6 (2019), p. 911-919
- Full Text:
- Reviewed:
- Description: Late 2017, the ban on the cultivation and consumption of low tetrahydrocannabinol (THC) Cannabis sativa L. in Victoria, was lifted by the Federal Government of Australia. Its legalization presents the opportunity for Victoria to become a leading producer and distributer of these economically valuable hemp products. However, as a novel crop to Victoria, there is little information available for obtaining economically viable yields. Therefore, the objectives of this review were to firstly, develop an understanding of the environmental requirements shared by C. sativa cultivars, and what conditions promote fibre and grain yields. Secondly, it seeks to identify what farming practices have been conducted throughout Europe, Canada and China, and to explore whether these practices could be adapted to Victoria. Thirdly, the review will assist in making recommendations regarding which cultivars would be 'potential' candidates for commencing trials under Victorian climates so to find out the varieties that can provide high yields for fibre, grain and dual-purpose production. This review notes that Victoria shares a similar climate to central Europe, and has an ideal climate for the development of a successful hemp industry, as it has suitable lengths of daylight throughout spring and summer months and meets the precipitation requirements. This review has thus strongly suggested that the properties and attributes of European varieties of C. sativa should be further researched for site-specific cultivation in Victoria for fibre, grain and dual-purpose production in order to maximise harvest yields. © 2007-2019 Southern Cross Publishing-Australia.
Influence of soil moisture regimes on growth, photosynthetic capacity, leaf biochemistry and reproductive capabilities of the invasive agronomic weed; Lactuca serriola
- Chadha, Aakansha, Florentine, Singarayer, Chauhan, Bhagirath, Long, Benjamin, Jayasundera, Mithila
- Authors: Chadha, Aakansha , Florentine, Singarayer , Chauhan, Bhagirath , Long, Benjamin , Jayasundera, Mithila
- Date: 2019
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 14, no. 6 (2019), p. 1-17
- Full Text:
- Reviewed:
- Description: Global temperatures are predicted to increase by 1.5–5.9C during this century, and this change is likely to impact average rainfall, with predictions that water deficit will perhaps be the most severe threat to sustainable agriculture. In this respect, invasive weeds, which have traits better adapted to drought stress than crops, add to concerns regarding crop sustainability. Lactuca serriola, an aggressive agronomic weed is thought to be a successful weed because of its ability to maintain high water use efficiency under drought conditions. In this study, experiments were conducted to examine the influence of different soil moisture regimes (100%, 75%, 50% and 25% water holding capacity (WHC)) on growth, photosynthetic capacity, leaf biochemistry and reproduction of this species. Soil moisture significantly affected plant’s height, stem diameter, number of leaves and biomass. The highest plant height (115.14 cm ± 11.64), shoot diameter (9.4 mm ± 0.18), leaf area (1206.5 mm2 ± 73.29), plant fresh weight (83.1 ± 3.98) and dry weight (22.38 ± 1.24) were recorded at 75% soil moisture content. A fundamental adaptation to drought was observed as plants in the 25% WHC treatment had the highest root: shoot ratio. Soluble sugars and total phenolic content were highest in the 25% WHC treatment and significantly different to 100% WHC which was a response to soil moisture stress to ameliorate the damaging effects of reactive oxygen species produced under stress conditions. Results also indicate that L. serriola can survive and produce seeds under water stress as more than 6000 seeds were produced per plant in all WHC treatments. In this study, there was no significant difference in the seed weight, number of seeds produced and their germination ability. This can have a huge impact on agricultural systems as the species can survive both under low and high soil moisture conditions. We therefore suggest that the demonstrated ability of L. serriola to complete its life cycle and produce biomass and seeds under water stressed conditions leads to the introduction of strategies that minimize weed survival while maximizing irrigation efficiency for the crop. A clear understanding of the ecological and biological characteristics of this weed will help land managers take appropriate control measures to mitigate the effect of this species on economic crop productivity.
- Authors: Chadha, Aakansha , Florentine, Singarayer , Chauhan, Bhagirath , Long, Benjamin , Jayasundera, Mithila
- Date: 2019
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 14, no. 6 (2019), p. 1-17
- Full Text:
- Reviewed:
- Description: Global temperatures are predicted to increase by 1.5–5.9C during this century, and this change is likely to impact average rainfall, with predictions that water deficit will perhaps be the most severe threat to sustainable agriculture. In this respect, invasive weeds, which have traits better adapted to drought stress than crops, add to concerns regarding crop sustainability. Lactuca serriola, an aggressive agronomic weed is thought to be a successful weed because of its ability to maintain high water use efficiency under drought conditions. In this study, experiments were conducted to examine the influence of different soil moisture regimes (100%, 75%, 50% and 25% water holding capacity (WHC)) on growth, photosynthetic capacity, leaf biochemistry and reproduction of this species. Soil moisture significantly affected plant’s height, stem diameter, number of leaves and biomass. The highest plant height (115.14 cm ± 11.64), shoot diameter (9.4 mm ± 0.18), leaf area (1206.5 mm2 ± 73.29), plant fresh weight (83.1 ± 3.98) and dry weight (22.38 ± 1.24) were recorded at 75% soil moisture content. A fundamental adaptation to drought was observed as plants in the 25% WHC treatment had the highest root: shoot ratio. Soluble sugars and total phenolic content were highest in the 25% WHC treatment and significantly different to 100% WHC which was a response to soil moisture stress to ameliorate the damaging effects of reactive oxygen species produced under stress conditions. Results also indicate that L. serriola can survive and produce seeds under water stress as more than 6000 seeds were produced per plant in all WHC treatments. In this study, there was no significant difference in the seed weight, number of seeds produced and their germination ability. This can have a huge impact on agricultural systems as the species can survive both under low and high soil moisture conditions. We therefore suggest that the demonstrated ability of L. serriola to complete its life cycle and produce biomass and seeds under water stressed conditions leads to the introduction of strategies that minimize weed survival while maximizing irrigation efficiency for the crop. A clear understanding of the ecological and biological characteristics of this weed will help land managers take appropriate control measures to mitigate the effect of this species on economic crop productivity.
Response of Chloris truncata to moisture stress, elevated carbon dioxide and herbicide application
- Weller, Sandra, Florentine, Singarayer, Mutti, Navneet, Jha, Prashant, Chauhan, Bhagirath
- Authors: Weller, Sandra , Florentine, Singarayer , Mutti, Navneet , Jha, Prashant , Chauhan, Bhagirath
- Date: 2019
- Type: Text , Journal article
- Relation: Scientific Reports Vol. 9, no. 1 (2019), p. 1-10
- Full Text:
- Reviewed:
- Description: Herbicide resistance has been observed in Chloris truncata, an Australian native C4 grass and a summer-fallow weed, which is common in no-till agriculture situations where herbicides are involved in crop management. To investigate the role of drought and increased atmospheric carbon dioxide (CO2) in determining weed growth, three trials were conducted using a ‘glyphosate-resistant’ and a ‘glyphosate-susceptible’ biotype. The first two trials tested the effect of herbicide (glyphosate) application on plant survival and growth under moisture stress and elevated CO2 respectively. A third trial investigated the effect on plant growth and reproduction under conditions of moisture stress and elevated CO2 in the absence of herbicide. In the first trial, water was withheld from half of the plants prior to application of glyphosate to all plants, and in the second trial plants were grown in either ambient (450 ppm) or elevated CO2 levels (750 ppm) prior to, and following, herbicide application. In both biotypes, herbicide effectiveness was reduced when plants were subjected to moisture stress or if grown in elevated CO2. Plant productivity, as measured by dry biomass per plant, was reduced with moisture stress, but increased with elevated CO2. In the third trial, growth rate, biomass and seed production were higher in the susceptible biotype compared to the resistant biotype. This suggests that a superior ability to resist herbicides may come at a cost to overall plant fitness. The results indicate that control of this weed may become difficult in the future as climatic conditions change. Supplementary information accompanies this paper at https://doi.org/10.1038/s41598-019-47237-x.
- Authors: Weller, Sandra , Florentine, Singarayer , Mutti, Navneet , Jha, Prashant , Chauhan, Bhagirath
- Date: 2019
- Type: Text , Journal article
- Relation: Scientific Reports Vol. 9, no. 1 (2019), p. 1-10
- Full Text:
- Reviewed:
- Description: Herbicide resistance has been observed in Chloris truncata, an Australian native C4 grass and a summer-fallow weed, which is common in no-till agriculture situations where herbicides are involved in crop management. To investigate the role of drought and increased atmospheric carbon dioxide (CO2) in determining weed growth, three trials were conducted using a ‘glyphosate-resistant’ and a ‘glyphosate-susceptible’ biotype. The first two trials tested the effect of herbicide (glyphosate) application on plant survival and growth under moisture stress and elevated CO2 respectively. A third trial investigated the effect on plant growth and reproduction under conditions of moisture stress and elevated CO2 in the absence of herbicide. In the first trial, water was withheld from half of the plants prior to application of glyphosate to all plants, and in the second trial plants were grown in either ambient (450 ppm) or elevated CO2 levels (750 ppm) prior to, and following, herbicide application. In both biotypes, herbicide effectiveness was reduced when plants were subjected to moisture stress or if grown in elevated CO2. Plant productivity, as measured by dry biomass per plant, was reduced with moisture stress, but increased with elevated CO2. In the third trial, growth rate, biomass and seed production were higher in the susceptible biotype compared to the resistant biotype. This suggests that a superior ability to resist herbicides may come at a cost to overall plant fitness. The results indicate that control of this weed may become difficult in the future as climatic conditions change. Supplementary information accompanies this paper at https://doi.org/10.1038/s41598-019-47237-x.
Seed germination ecology of Bidens pilosa and its implications for weed management
- Chauhan, Bhagirath, Ali, Hafiz, Florentine, Singarayer
- Authors: Chauhan, Bhagirath , Ali, Hafiz , Florentine, Singarayer
- Date: 2019
- Type: Text , Journal article
- Relation: Scientific Reports Vol. 9, no. 1 (2019), p.
- Full Text:
- Reviewed:
- Description: It is now widely recognized that Bidens pilosa has become a problematic broadleaf weed in many ecosystems across the world and, particularly in the light of recent climate change conditions, closer management strategies are required to curtail its impact on agricultural cropping. In this investigation, experiments were conducted to evaluate the effect of environmental factors on the germination and emergence of B. pilosa, and also on the response of this weed to commonly available post-emergence herbicides in Australia. The environmental factors of particular interest to this current work were the effect of light and temperature, salinity, burial depth and moisture on B. pilosa since these are key management issues in Australian agriculture. In addition, the effects of a number of commonly used herbicides were examined, because of concerns regarding emerging herbicide resistance. In the tested light/dark regimes, germination was found to be higher at fluctuating day/night temperatures of 25/15 °C and 30/20 °C (92–93%) than at 35/25 °C (79%), whilst across the different temperature ranges, germination was higher in the light/dark regime (79–93%) than in complete darkness (22–38%). The standard five-minute temperature pretreatment required for 50% inhibition of maximum germination was found to be 160 °C, and it was further shown that no seeds germinated at temperatures higher than 240 °C. With regard to salinity, some B. pilosa seeds germinated (3%) in 200 mM sodium chloride (NaCl) but all failed to germinate at 250 mM NaCl. Germination declined from 89% to 2% as the external osmotic potential decreased from 0 to −0.6 MPa, and germination ceased at −0.8 MPa. Seeding emergence of B. pilosa was maximum (71%) for seeds placed on the soil surface and it was found that no seedlings emerged from a depth of 8 cm or greater. A depth of 3.75 cm was required to inhibit the seeds to 50% of the maximum emergence. In this study, application of glufosinate, glyphosate and paraquat provided commercially acceptable control levels (generally accepted as >90%) when applied at the four-leaf stage of B. pilosa. However, none of the herbicide treatments involved in this study provided this level of control when applied at the six-leaf stage. In summary, B. pilosa germination has been clearly shown to be stimulated by light and thus its emergence was greatest from the soil surface. This suggests that infestation from this weed will remain as a problem in no-till conservation agriculture systems, the use of which is increasing now throughout the world. It is intended that information generated from this study be used to develop more effective integrated management programs for B. pilosa and similar weeds in commercial agricultural environments which are tending toward conservation approaches. © 2019, The Author(s).
- Authors: Chauhan, Bhagirath , Ali, Hafiz , Florentine, Singarayer
- Date: 2019
- Type: Text , Journal article
- Relation: Scientific Reports Vol. 9, no. 1 (2019), p.
- Full Text:
- Reviewed:
- Description: It is now widely recognized that Bidens pilosa has become a problematic broadleaf weed in many ecosystems across the world and, particularly in the light of recent climate change conditions, closer management strategies are required to curtail its impact on agricultural cropping. In this investigation, experiments were conducted to evaluate the effect of environmental factors on the germination and emergence of B. pilosa, and also on the response of this weed to commonly available post-emergence herbicides in Australia. The environmental factors of particular interest to this current work were the effect of light and temperature, salinity, burial depth and moisture on B. pilosa since these are key management issues in Australian agriculture. In addition, the effects of a number of commonly used herbicides were examined, because of concerns regarding emerging herbicide resistance. In the tested light/dark regimes, germination was found to be higher at fluctuating day/night temperatures of 25/15 °C and 30/20 °C (92–93%) than at 35/25 °C (79%), whilst across the different temperature ranges, germination was higher in the light/dark regime (79–93%) than in complete darkness (22–38%). The standard five-minute temperature pretreatment required for 50% inhibition of maximum germination was found to be 160 °C, and it was further shown that no seeds germinated at temperatures higher than 240 °C. With regard to salinity, some B. pilosa seeds germinated (3%) in 200 mM sodium chloride (NaCl) but all failed to germinate at 250 mM NaCl. Germination declined from 89% to 2% as the external osmotic potential decreased from 0 to −0.6 MPa, and germination ceased at −0.8 MPa. Seeding emergence of B. pilosa was maximum (71%) for seeds placed on the soil surface and it was found that no seedlings emerged from a depth of 8 cm or greater. A depth of 3.75 cm was required to inhibit the seeds to 50% of the maximum emergence. In this study, application of glufosinate, glyphosate and paraquat provided commercially acceptable control levels (generally accepted as >90%) when applied at the four-leaf stage of B. pilosa. However, none of the herbicide treatments involved in this study provided this level of control when applied at the six-leaf stage. In summary, B. pilosa germination has been clearly shown to be stimulated by light and thus its emergence was greatest from the soil surface. This suggests that infestation from this weed will remain as a problem in no-till conservation agriculture systems, the use of which is increasing now throughout the world. It is intended that information generated from this study be used to develop more effective integrated management programs for B. pilosa and similar weeds in commercial agricultural environments which are tending toward conservation approaches. © 2019, The Author(s).
Characterizing selected soil attributes of different land-use management to assess reforestation benefits of deforested riparian buffers
- Rasiah, Velu, Florentine, Singarayer
- Authors: Rasiah, Velu , Florentine, Singarayer
- Date: 2018
- Type: Text , Journal article
- Relation: Ecological Processes Vol. 7, no. 1 (2018), p. 1-12
- Full Text:
- Reviewed:
- Description: Introduction: The information available on the sensitivity of soil biotic and abiotic attributes, which can be used to track the impact of reforestation in riparian buffers, is often insufficient to refine management practices and convince stakeholders of the benefits of reforestation. Methods: In this study, conducted in Victoria, Australia, the changes in soil biotic and abiotic attributes, organic carbon (OC), mineral nitrogen (MN), total dissolved solutes (TDS) and pH were characterised to assess the impact of land-use change from bare riparian (BR) to reforested riparian (RR). Additionally, the benefits of revegetating a deforested creek bank with regard to salinity abatement and C-sequestration potentials were assessed. Results: The TDS depletion in the RR strips varied spatiotemporally from 65 to 169 mg/L, the net OC deposition from 16 to 19 g C/kg soil and MN deposition from 1.2 to 2.1 g N/kg soil, respectively. Additionally, the net changes in pH from alkaline to near neutral condition varied by 0.4 to 1.0 pH units. Approximately 30% to 60% of the net OC depletion after deforestation was redeposited under RR over 3 to 6 years. The TDS depletion after land-use changed from BR to RR ranged from 15 to 32% over 3 to 6 years. Conclusion: The soil attributes OC, MN and TDS characteristics under different land-use practices varied spatiotemporally. This information may be useful to convince stakeholders to undertake reforestation of creek banks for salinity abatement, and that change in land-use has the potential to increase C sequestration at a farm scale.
- Authors: Rasiah, Velu , Florentine, Singarayer
- Date: 2018
- Type: Text , Journal article
- Relation: Ecological Processes Vol. 7, no. 1 (2018), p. 1-12
- Full Text:
- Reviewed:
- Description: Introduction: The information available on the sensitivity of soil biotic and abiotic attributes, which can be used to track the impact of reforestation in riparian buffers, is often insufficient to refine management practices and convince stakeholders of the benefits of reforestation. Methods: In this study, conducted in Victoria, Australia, the changes in soil biotic and abiotic attributes, organic carbon (OC), mineral nitrogen (MN), total dissolved solutes (TDS) and pH were characterised to assess the impact of land-use change from bare riparian (BR) to reforested riparian (RR). Additionally, the benefits of revegetating a deforested creek bank with regard to salinity abatement and C-sequestration potentials were assessed. Results: The TDS depletion in the RR strips varied spatiotemporally from 65 to 169 mg/L, the net OC deposition from 16 to 19 g C/kg soil and MN deposition from 1.2 to 2.1 g N/kg soil, respectively. Additionally, the net changes in pH from alkaline to near neutral condition varied by 0.4 to 1.0 pH units. Approximately 30% to 60% of the net OC depletion after deforestation was redeposited under RR over 3 to 6 years. The TDS depletion after land-use changed from BR to RR ranged from 15 to 32% over 3 to 6 years. Conclusion: The soil attributes OC, MN and TDS characteristics under different land-use practices varied spatiotemporally. This information may be useful to convince stakeholders to undertake reforestation of creek banks for salinity abatement, and that change in land-use has the potential to increase C sequestration at a farm scale.
Effect of environmental factors on the germination and emergence of Salvia verbenaca L. cultivars (verbenaca and vernalis) : An invasive species in semi-arid and arid rangeland regions
- Javaid, Muhammad, Florentine, Singarayer, Ali, Hafiz, Weller, Sandra
- Authors: Javaid, Muhammad , Florentine, Singarayer , Ali, Hafiz , Weller, Sandra
- Date: 2018
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 13, no. 3 (2018), p. 1-20
- Full Text:
- Reviewed:
- Description: Salvia verbenaca (wild sage) is a commonly cultivated herbal medicine plant, which is native to the Mediterranean climate regions of Europe, Africa, Asia and the Middle East. However, it has become an invasive species in semi-arid and arid regions of southern Australia. Two varieties are present in this region, var. verbenaca and var. vernalis, each of which can be distinguished by differences in morphology and flowering period. Following trials to determine the optimum temperate regime for germination and response to light and dark, seeds of both varieties were tested for their response to variations in pH, moisture stress, salinity, and burial depth. The temperature and light trial was carried out using three different temperature regimes; 30/20C, 25/15C and 20/12C, and two light regimes; 12 hours light/12 hours dark and 24 hours dark, with var. vernalis responding to relatively higher temperatures than var. verbenaca. The germination rate of neither species was significantly inhibited by complete darkness when compared to rates under periodic light exposure. Both varieties germinated at near optimum rates strongly to very strongly in all pH buffer solutions, from pH 5 to pH 10, but they responded most strongly at neutral pH. Var. vernalis showed slightly more tolerance to reduced moisture availability, moderate to strong salinity, and burial depth, compared to var. verbenaca. However, even a fairly shallow burial depth of 2 cm completely inhibited germination of both varieties. Thus, in circumstances where both varieties are present in a soil seedbank, var. vernalis could be expected to establish in more challenging conditions, where moisture is limited and salinity is ‘moderate to high’, implying that it is a more serious threat for invasive weed in conditions where crop plants are already challenged.
- Authors: Javaid, Muhammad , Florentine, Singarayer , Ali, Hafiz , Weller, Sandra
- Date: 2018
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 13, no. 3 (2018), p. 1-20
- Full Text:
- Reviewed:
- Description: Salvia verbenaca (wild sage) is a commonly cultivated herbal medicine plant, which is native to the Mediterranean climate regions of Europe, Africa, Asia and the Middle East. However, it has become an invasive species in semi-arid and arid regions of southern Australia. Two varieties are present in this region, var. verbenaca and var. vernalis, each of which can be distinguished by differences in morphology and flowering period. Following trials to determine the optimum temperate regime for germination and response to light and dark, seeds of both varieties were tested for their response to variations in pH, moisture stress, salinity, and burial depth. The temperature and light trial was carried out using three different temperature regimes; 30/20C, 25/15C and 20/12C, and two light regimes; 12 hours light/12 hours dark and 24 hours dark, with var. vernalis responding to relatively higher temperatures than var. verbenaca. The germination rate of neither species was significantly inhibited by complete darkness when compared to rates under periodic light exposure. Both varieties germinated at near optimum rates strongly to very strongly in all pH buffer solutions, from pH 5 to pH 10, but they responded most strongly at neutral pH. Var. vernalis showed slightly more tolerance to reduced moisture availability, moderate to strong salinity, and burial depth, compared to var. verbenaca. However, even a fairly shallow burial depth of 2 cm completely inhibited germination of both varieties. Thus, in circumstances where both varieties are present in a soil seedbank, var. vernalis could be expected to establish in more challenging conditions, where moisture is limited and salinity is ‘moderate to high’, implying that it is a more serious threat for invasive weed in conditions where crop plants are already challenged.
Environmental factors effecting the germination and seedling emergence of two populations of an aggressive agricultural weed; Nassella trichotoma
- Humphries, Talia, Chauhan, Bhagirath, Florentine, Singarayer
- Authors: Humphries, Talia , Chauhan, Bhagirath , Florentine, Singarayer
- Date: 2018
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 13, no. 7 (2018), p. 1-25
- Full Text:
- Reviewed:
- Description: Nassella trichotoma (Nees) Hack. ex Arechav. (Serrated tussock) is an aggressive globally significant weed to agricultural and natural ecosystems. Herbicide resistant populations of this C3 perennial weed have emerged, increasing the need for effective wide-scale cultural control strategies. A thorough seed ecology study on two spatially distinct populations of N. trichotoma was conducted on this weed to identify differences in important environmental factors (drought, salinity, alternating temperature, photoperiod, burial depth, soil pH, artificial seed aging, and radiant heat) which influence seed dormancy. Seeds were collected from two spatially distinct populations; Gnarwarre (38 O 9’ 8.892’’ S, 144 O 7’ 38.784’’ E) and Ingliston (37O 40’ 4.44’’ S, 144 O 18’ 39.24’’ E) in December 2016 and February 2017, respectively. Twenty sterilized seeds were placed into Petri dishes lined with a single Whatman® No. 10 filter paper dampened with the relevant treatments solution and then incubated under the identified optimal alternating temperature and photoperiod regime of 25C/ 15C (light/dark, 12h/12h). For the burial depth treatment, 20 seeds were placed into plastic containers (10cm in diameter and 6cm in depth) and buried to the relevant depth in sterilized soil. All trials were monitored for 30 days and germination was indicated by 5mm exposure of the radicle and emergence was indicated by the exposure of the cotyledon. Each treatment had three replicates for each population, and each treatment was repeated to give a total of six replicates per treatment, per population. Nassella trichotoma was identified to be non-photoblastic, with germination (%) being similar under alternating light and dark and complete darkness conditions. With an increase of osmotic potential and salinity, a significant decline in germination was observed. There was no effect of pH on germination. Exposure to a radiant heat of 120C for 9 minutes resulted in the lowest germination in the Ingliston population (33%) and the Gnarwarre population (60%). In the burial depth treatment, the Ingliston population and the Gnarwarre population had highest emergence of 75% and 80%, respectively at a depth of 1cm. Variation between the two populations was observed for the burial depth treatments; Gnarwarre had greater emergence than Ingliston from the 4cm burial depth, while Ingliston had greater emergence at the soil surface than Gnarwarre. The Gnarwarre population had greater overall germination than Ingliston, which could be attributed to the greater seed mass (0.86mg compared to 0.76mg, respectively). This study identifies that spatial variations in N. trichotoma’s seed ecology are present between spatially distinct populations.
- Authors: Humphries, Talia , Chauhan, Bhagirath , Florentine, Singarayer
- Date: 2018
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 13, no. 7 (2018), p. 1-25
- Full Text:
- Reviewed:
- Description: Nassella trichotoma (Nees) Hack. ex Arechav. (Serrated tussock) is an aggressive globally significant weed to agricultural and natural ecosystems. Herbicide resistant populations of this C3 perennial weed have emerged, increasing the need for effective wide-scale cultural control strategies. A thorough seed ecology study on two spatially distinct populations of N. trichotoma was conducted on this weed to identify differences in important environmental factors (drought, salinity, alternating temperature, photoperiod, burial depth, soil pH, artificial seed aging, and radiant heat) which influence seed dormancy. Seeds were collected from two spatially distinct populations; Gnarwarre (38 O 9’ 8.892’’ S, 144 O 7’ 38.784’’ E) and Ingliston (37O 40’ 4.44’’ S, 144 O 18’ 39.24’’ E) in December 2016 and February 2017, respectively. Twenty sterilized seeds were placed into Petri dishes lined with a single Whatman® No. 10 filter paper dampened with the relevant treatments solution and then incubated under the identified optimal alternating temperature and photoperiod regime of 25C/ 15C (light/dark, 12h/12h). For the burial depth treatment, 20 seeds were placed into plastic containers (10cm in diameter and 6cm in depth) and buried to the relevant depth in sterilized soil. All trials were monitored for 30 days and germination was indicated by 5mm exposure of the radicle and emergence was indicated by the exposure of the cotyledon. Each treatment had three replicates for each population, and each treatment was repeated to give a total of six replicates per treatment, per population. Nassella trichotoma was identified to be non-photoblastic, with germination (%) being similar under alternating light and dark and complete darkness conditions. With an increase of osmotic potential and salinity, a significant decline in germination was observed. There was no effect of pH on germination. Exposure to a radiant heat of 120C for 9 minutes resulted in the lowest germination in the Ingliston population (33%) and the Gnarwarre population (60%). In the burial depth treatment, the Ingliston population and the Gnarwarre population had highest emergence of 75% and 80%, respectively at a depth of 1cm. Variation between the two populations was observed for the burial depth treatments; Gnarwarre had greater emergence than Ingliston from the 4cm burial depth, while Ingliston had greater emergence at the soil surface than Gnarwarre. The Gnarwarre population had greater overall germination than Ingliston, which could be attributed to the greater seed mass (0.86mg compared to 0.76mg, respectively). This study identifies that spatial variations in N. trichotoma’s seed ecology are present between spatially distinct populations.
Germination ecology of Chloris truncata and its implication for weed management
- Chauhan, Bhagirath, Manalil, Sudheesh, Florentine, Singarayer, Jha, Prashant
- Authors: Chauhan, Bhagirath , Manalil, Sudheesh , Florentine, Singarayer , Jha, Prashant
- Date: 2018
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 13, no. 7 (2018), p. 1-13
- Full Text:
- Reviewed:
- Description: Chloris truncata is a significant weed in summer crops in the subtropical region of Australia. A study was conducted to evaluate the effect of environmental factors on germination and emergence of two populations of C. truncata. Overall, germination was not affected by the populations. Seeds germinated at a wide range of alternating day/night temperatures, suggesting that seeds can germinate throughout the spring, winter and autumn seasons. Seed germination was stimulated by the presence of light; however, 51 to 71% of these seeds still germinated in the dark. The sodium chloride concentration and osmotic potential required to inhibit germination of 50% of the population were 179 mM and -0.52 MPa, respectively. A high proportion of seeds germinated over a wide pH range (4 to 10). Seeds placed on the soil surface had greatest germination (67%) and a burial depth of 3 cm resulted in complete inhibition of emergence. The sorghum residue amount required to reduce emergence by 50% was 1.8 t ha-1. The results suggest that, although this weed will be favored in no-till systems, residue retention on the soil surface will help in reducing its infestation. Seed bank buildup can be managed by burying seeds below the depth of emergence. © 2018 Chauhan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
- Authors: Chauhan, Bhagirath , Manalil, Sudheesh , Florentine, Singarayer , Jha, Prashant
- Date: 2018
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 13, no. 7 (2018), p. 1-13
- Full Text:
- Reviewed:
- Description: Chloris truncata is a significant weed in summer crops in the subtropical region of Australia. A study was conducted to evaluate the effect of environmental factors on germination and emergence of two populations of C. truncata. Overall, germination was not affected by the populations. Seeds germinated at a wide range of alternating day/night temperatures, suggesting that seeds can germinate throughout the spring, winter and autumn seasons. Seed germination was stimulated by the presence of light; however, 51 to 71% of these seeds still germinated in the dark. The sodium chloride concentration and osmotic potential required to inhibit germination of 50% of the population were 179 mM and -0.52 MPa, respectively. A high proportion of seeds germinated over a wide pH range (4 to 10). Seeds placed on the soil surface had greatest germination (67%) and a burial depth of 3 cm resulted in complete inhibition of emergence. The sorghum residue amount required to reduce emergence by 50% was 1.8 t ha-1. The results suggest that, although this weed will be favored in no-till systems, residue retention on the soil surface will help in reducing its infestation. Seed bank buildup can be managed by burying seeds below the depth of emergence. © 2018 Chauhan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Emerging challenges and opportunities for education and research in weed science
- Chauhan, Bhagirath, Matloob, Amar, Mahajan, Gulshan, Aslam, Farhena, Florentine, Singarayer, Jha, Prashant
- Authors: Chauhan, Bhagirath , Matloob, Amar , Mahajan, Gulshan , Aslam, Farhena , Florentine, Singarayer , Jha, Prashant
- Date: 2017
- Type: Text , Journal article
- Relation: Frontiers in Plant Science Vol. 8, no. (2017), p. 1-13
- Full Text:
- Reviewed:
- Description: In modern agriculture, with more emphasis on high input systems, weed problems are likely to increase and become more complex. With heightened awareness of adverse effects of herbicide residues on human health and environment and the evolution of herbicide-resistant weed biotypes, a significant focus within weed science has now shifted to the development of eco-friendly technologies with reduced reliance on herbicides. Further, with the large-scale adoption of herbicide-resistant crops, and uncertain climatic optima under climate change, the problems for weed science have become multi-faceted. To handle these complex weed problems, a holistic line of action with multi-disciplinary approaches is required, including adjustments to technology, management practices, and legislation. Improved knowledge of weed ecology, biology, genetics, and molecular biology is essential for developing sustainable weed control practices. Additionally, judicious use of advanced technologies, such as site-specific weed management systems and decision support modeling, will play a significant role in reducing costs associated with weed control. Further, effective linkages between farmers and weed researchers will be necessary to facilitate the adoption of technological developments. To meet these challenges, priorities in research need to be determined and the education system for weed science needs to be reoriented. In respect of the latter imperative, closer collaboration between weed scientists and other disciplines can help in defining and solving the complex weed management challenges of the 21st century. This consensus will provide more versatile and diverse approaches to innovative teaching and training practices, which will be needed to prepare future weed science graduates who are capable of handling the anticipated challenges of weed science facing in contemporary agriculture. To build this capacity, mobilizing additional funding for both weed research and weed management education is essential. © 2017 Chauhan, Matloob, Mahajan, Aslam, Florentine and Jha.
- Authors: Chauhan, Bhagirath , Matloob, Amar , Mahajan, Gulshan , Aslam, Farhena , Florentine, Singarayer , Jha, Prashant
- Date: 2017
- Type: Text , Journal article
- Relation: Frontiers in Plant Science Vol. 8, no. (2017), p. 1-13
- Full Text:
- Reviewed:
- Description: In modern agriculture, with more emphasis on high input systems, weed problems are likely to increase and become more complex. With heightened awareness of adverse effects of herbicide residues on human health and environment and the evolution of herbicide-resistant weed biotypes, a significant focus within weed science has now shifted to the development of eco-friendly technologies with reduced reliance on herbicides. Further, with the large-scale adoption of herbicide-resistant crops, and uncertain climatic optima under climate change, the problems for weed science have become multi-faceted. To handle these complex weed problems, a holistic line of action with multi-disciplinary approaches is required, including adjustments to technology, management practices, and legislation. Improved knowledge of weed ecology, biology, genetics, and molecular biology is essential for developing sustainable weed control practices. Additionally, judicious use of advanced technologies, such as site-specific weed management systems and decision support modeling, will play a significant role in reducing costs associated with weed control. Further, effective linkages between farmers and weed researchers will be necessary to facilitate the adoption of technological developments. To meet these challenges, priorities in research need to be determined and the education system for weed science needs to be reoriented. In respect of the latter imperative, closer collaboration between weed scientists and other disciplines can help in defining and solving the complex weed management challenges of the 21st century. This consensus will provide more versatile and diverse approaches to innovative teaching and training practices, which will be needed to prepare future weed science graduates who are capable of handling the anticipated challenges of weed science facing in contemporary agriculture. To build this capacity, mobilizing additional funding for both weed research and weed management education is essential. © 2017 Chauhan, Matloob, Mahajan, Aslam, Florentine and Jha.
Weeds in a changing climate : Vulnerabilities, consequences, and implications for future weed management
- Ramesh, Kulasekaran, Matloob, Amar, Aslam, Farhena, Florentine, Singarayer, Chauhan, Bhagirath
- Authors: Ramesh, Kulasekaran , Matloob, Amar , Aslam, Farhena , Florentine, Singarayer , Chauhan, Bhagirath
- Date: 2017
- Type: Text , Journal article
- Relation: Frontiers in Plant Science Vol. 8, no. (2017), p. 1-13
- Full Text:
- Reviewed:
- Description: Whilst it is agreed that climate change will impact on the long-term interactions between crops and weeds, the results of this impact are far from clear. We suggest that a thorough understanding of weed dominance and weed interactions, depending on crop and weed ecosystems and crop sequences in the ecosystem, will be the key determining factor for successful weed management. Indeed, we claim that recent changes observed throughout the world within the weed spectrum in different cropping systems which were ostensibly related to climate change, warrant a deeper examination of weed vulnerabilities before a full understanding is reached. For example, the uncontrolled establishment of weeds in crops leads to a mixed population, in terms of C3 and C4 pathways, and this poses a considerable level of complexity for weed management. There is a need to include all possible combinations of crops and weeds while studying the impact of climate change on crop-weed competitive interactions, since, from a weed management perspective, C4 weeds would flourish in the increased temperature scenario and pose serious yield penalties. This is particularly alarming as a majority of the most competitive weeds are C4 plants. Although CO2 is considered as a main contributing factor for climate change, a few Australian studies have also predicted differing responses of weed species due to shifts in rainfall patterns. Reduced water availability, due to recurrent and unforeseen droughts, would alter the competitive balance between crops and some weed species, intensifying the crop-weed competition pressure. Although it is recognized that the weed pressure associated with climate change is a significant threat to crop production, either through increased temperatures, rainfall shift, and elevated CO2 levels, the current knowledge of this effect is very sparse. A few models that have attempted to predict these interactions are discussed in this paper, since these models could play an integral role in developing future management programs for future weed threats. This review has presented a comprehensive discussion of the recent research in this area, and has identified key deficiencies which need further research in crop-weed eco-systems to formulate suitable control measures before the real impacts of climate change set in. © 2017 Ramesh, Matloob, Aslam, Florentine and Chauhan.
- Authors: Ramesh, Kulasekaran , Matloob, Amar , Aslam, Farhena , Florentine, Singarayer , Chauhan, Bhagirath
- Date: 2017
- Type: Text , Journal article
- Relation: Frontiers in Plant Science Vol. 8, no. (2017), p. 1-13
- Full Text:
- Reviewed:
- Description: Whilst it is agreed that climate change will impact on the long-term interactions between crops and weeds, the results of this impact are far from clear. We suggest that a thorough understanding of weed dominance and weed interactions, depending on crop and weed ecosystems and crop sequences in the ecosystem, will be the key determining factor for successful weed management. Indeed, we claim that recent changes observed throughout the world within the weed spectrum in different cropping systems which were ostensibly related to climate change, warrant a deeper examination of weed vulnerabilities before a full understanding is reached. For example, the uncontrolled establishment of weeds in crops leads to a mixed population, in terms of C3 and C4 pathways, and this poses a considerable level of complexity for weed management. There is a need to include all possible combinations of crops and weeds while studying the impact of climate change on crop-weed competitive interactions, since, from a weed management perspective, C4 weeds would flourish in the increased temperature scenario and pose serious yield penalties. This is particularly alarming as a majority of the most competitive weeds are C4 plants. Although CO2 is considered as a main contributing factor for climate change, a few Australian studies have also predicted differing responses of weed species due to shifts in rainfall patterns. Reduced water availability, due to recurrent and unforeseen droughts, would alter the competitive balance between crops and some weed species, intensifying the crop-weed competition pressure. Although it is recognized that the weed pressure associated with climate change is a significant threat to crop production, either through increased temperatures, rainfall shift, and elevated CO2 levels, the current knowledge of this effect is very sparse. A few models that have attempted to predict these interactions are discussed in this paper, since these models could play an integral role in developing future management programs for future weed threats. This review has presented a comprehensive discussion of the recent research in this area, and has identified key deficiencies which need further research in crop-weed eco-systems to formulate suitable control measures before the real impacts of climate change set in. © 2017 Ramesh, Matloob, Aslam, Florentine and Chauhan.
An investigation of the effects of stage of ensilage on Nassella neesiana seeds, for reducing seed viability and injury to livestock
- Weller, Sandra, Florentine, Singarayer, Sillitoe, Jim, Grech, Charles, McLaren, David
- Authors: Weller, Sandra , Florentine, Singarayer , Sillitoe, Jim , Grech, Charles , McLaren, David
- Date: 2016
- Type: Text , Journal article
- Relation: Scientific Reports Vol. 6, no. (2016), p. 1-7
- Full Text:
- Reviewed:
- Description: The noxious weed Nassella neesiana is established on a wide range of productive land throughout southeastern Australia. N. neesiana seeds, when mature, are sharp, causing injury to livestock, thus posing a problem in fodder bales. To reduce infestations of agricultural weeds in situ, production of silage from weed-infested pastures is practised as part of integrated weed management (IWM). However, there is little data to demonstrate whether this process is useful to reduce infestations or the harmful properties of N. neesiana. Therefore, the minimum duration of ensilage required to reduce the viability of N. neesiana seeds was investigated, both with and without addition of ensilage inoculants in this process. Also, the decreasing propensity of the seeds to injure livestock, after various times and conditions of ensilage, was assessed. Ensilage inoculant reduced seed germination probability to zero after 35 days. When no inoculant was added, zero viability was achieved after 42 days. A qualitative assessment of the hardness of ensilaged seeds found seed husks were softer (and therefore safer) after 42 days, whether inoculant was used or not. Therefore, we suggest that both the viability of N. neesiana seeds and hardness of seed casings are significantly reduced after 42 days, thereby reducing the risks of seed dispersal and injury to livestock.
- Authors: Weller, Sandra , Florentine, Singarayer , Sillitoe, Jim , Grech, Charles , McLaren, David
- Date: 2016
- Type: Text , Journal article
- Relation: Scientific Reports Vol. 6, no. (2016), p. 1-7
- Full Text:
- Reviewed:
- Description: The noxious weed Nassella neesiana is established on a wide range of productive land throughout southeastern Australia. N. neesiana seeds, when mature, are sharp, causing injury to livestock, thus posing a problem in fodder bales. To reduce infestations of agricultural weeds in situ, production of silage from weed-infested pastures is practised as part of integrated weed management (IWM). However, there is little data to demonstrate whether this process is useful to reduce infestations or the harmful properties of N. neesiana. Therefore, the minimum duration of ensilage required to reduce the viability of N. neesiana seeds was investigated, both with and without addition of ensilage inoculants in this process. Also, the decreasing propensity of the seeds to injure livestock, after various times and conditions of ensilage, was assessed. Ensilage inoculant reduced seed germination probability to zero after 35 days. When no inoculant was added, zero viability was achieved after 42 days. A qualitative assessment of the hardness of ensilaged seeds found seed husks were softer (and therefore safer) after 42 days, whether inoculant was used or not. Therefore, we suggest that both the viability of N. neesiana seeds and hardness of seed casings are significantly reduced after 42 days, thereby reducing the risks of seed dispersal and injury to livestock.
Glyphosate Resistance of C-3 and C-4 Weeds under Rising Atmospheric CO2
- Fernando, Nimesha, Manalil, Sudheesh, Florentine, Singarayer, Chauhan, Bhagirath, Seneweera, Saman
- Authors: Fernando, Nimesha , Manalil, Sudheesh , Florentine, Singarayer , Chauhan, Bhagirath , Seneweera, Saman
- Date: 2016
- Type: Text , Journal article , Review
- Relation: Frontiers in Plant Science Vol. 7, no. (Jun 2016), p. 1-11
- Full Text:
- Reviewed:
- Description: The present paper reviews current knowledge on how changes of plant metabolism under elevated CO2 concentrations (e[CO2]) can affect the development of the glyphosate resistance of C-3 and C-4 weeds. Among the chemical herbicides, glyphosate, which is a non-selective and post-emergence herbicide, is currently the most widely used herbicide in global agriculture. As a consequence, glyphosate resistant weeds, particularly in major field crops, are a widespread problem and are becoming a significant challenge to future global food production. Of particular interest here it is known that the biochemical processes involved in photosynthetic pathways of C-3 and C-4 plants are different, which may have relevance to their competitive development under changing environmental conditions. It has already been shown that plant anatomical, morphological, and physiological changes under e[CO2] can be different, based on (i) the plant's functional group, (ii) the available soil nutrients, and (iii) the governing water status. In this respect, C-3 species are likely to have a major developmental advantage under a CO2 rich atmosphere, by being able to capitalize on the overall stimulatory effect of e[CO2]. For example, many tropical weed grass species fix CO2 from the atmosphere via the C-4 photosynthetic pathway, which is a complex anatomical and biochemical variant of the C-3 pathway. Thus, based on our current knowledge of CO2 fixing, it would appear obvious that the development of a glyphosate-resistant mechanism would be easier under an e[CO2] in C-3 weeds which have a simpler photosynthetic pathway, than for C-4 weeds. However, notwithstanding this logical argument, a better understanding of the biochemical, genetic, and molecular measures by which plants develop glyphosate resistance and how e[CO2] affects these measures will be important before attempting to innovate sustainable technology to manage the glyphosate-resistant evolution of weeds under e[CO2]. Such information will be of essential in managing weed control by herbicide use, and to thus ensure an increase in global food production in the event of increased atmospheric [CO2] levels.
- Authors: Fernando, Nimesha , Manalil, Sudheesh , Florentine, Singarayer , Chauhan, Bhagirath , Seneweera, Saman
- Date: 2016
- Type: Text , Journal article , Review
- Relation: Frontiers in Plant Science Vol. 7, no. (Jun 2016), p. 1-11
- Full Text:
- Reviewed:
- Description: The present paper reviews current knowledge on how changes of plant metabolism under elevated CO2 concentrations (e[CO2]) can affect the development of the glyphosate resistance of C-3 and C-4 weeds. Among the chemical herbicides, glyphosate, which is a non-selective and post-emergence herbicide, is currently the most widely used herbicide in global agriculture. As a consequence, glyphosate resistant weeds, particularly in major field crops, are a widespread problem and are becoming a significant challenge to future global food production. Of particular interest here it is known that the biochemical processes involved in photosynthetic pathways of C-3 and C-4 plants are different, which may have relevance to their competitive development under changing environmental conditions. It has already been shown that plant anatomical, morphological, and physiological changes under e[CO2] can be different, based on (i) the plant's functional group, (ii) the available soil nutrients, and (iii) the governing water status. In this respect, C-3 species are likely to have a major developmental advantage under a CO2 rich atmosphere, by being able to capitalize on the overall stimulatory effect of e[CO2]. For example, many tropical weed grass species fix CO2 from the atmosphere via the C-4 photosynthetic pathway, which is a complex anatomical and biochemical variant of the C-3 pathway. Thus, based on our current knowledge of CO2 fixing, it would appear obvious that the development of a glyphosate-resistant mechanism would be easier under an e[CO2] in C-3 weeds which have a simpler photosynthetic pathway, than for C-4 weeds. However, notwithstanding this logical argument, a better understanding of the biochemical, genetic, and molecular measures by which plants develop glyphosate resistance and how e[CO2] affects these measures will be important before attempting to innovate sustainable technology to manage the glyphosate-resistant evolution of weeds under e[CO2]. Such information will be of essential in managing weed control by herbicide use, and to thus ensure an increase in global food production in the event of increased atmospheric [CO2] levels.