Amaranthus retroflexus L (redroot pigweed) : effects of elevated CO2 and soil moisture on growth and biomass and the effect of radiant heat on seed germination
- Weller, Sandra, Florentine, Singarayer, Welgama, Amali, Chadha, Aakansha, Turville, Christopher
- Authors: Weller, Sandra , Florentine, Singarayer , Welgama, Amali , Chadha, Aakansha , Turville, Christopher
- Date: 2021
- Type: Text , Journal article
- Relation: Agronomy Vol. 11, no. 4 (2021), p.
- Full Text:
- Reviewed:
- Description: Amaranthus retroflexus L. (Amaranthaceae), Redroot pigweed, is native to North America, but has become a weed of agriculture worldwide. Previous research into competition with food crops found it significantly reduces yields. Additionally, taxonomy, biomass allocation, physiological responses to light intensity, water stress, elevated CO2, and herbicide resistance have been inves-tigated. To extend other research findings, we investigated growth and biomass yield in response to (i) soil moisture stress, and (ii) drought and elevated CO2. Additionally, we investigated seed germination rates following exposure to three elevated temperatures for two different time periods. Overall, moisture stress reduced plant height, stem diameter, and number of leaves. Elevated CO2 (700 ppm) appeared to reduce negative impacts of drought on biomass productivity. Heating seeds at 120◦C and above for either 180 or 300 s significantly reduced germination rate. These results inform an understanding of potential responses of A. retroflexus to future climate change and will be used to predict future occurrence of this weed. The finding that exposing seeds to high temperatures retards germination suggests fire could be used to prevent seed germination from soil seed banks, particularly in no-till situations, and therefore may be used to address infestations or prevent further spread of this weed. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. **Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliates “Sandra Weller, Singarayer Florentine, Amali Welgama, Aakansha Chadha, Chrisopher Turville" are provided in this record**
- Authors: Weller, Sandra , Florentine, Singarayer , Welgama, Amali , Chadha, Aakansha , Turville, Christopher
- Date: 2021
- Type: Text , Journal article
- Relation: Agronomy Vol. 11, no. 4 (2021), p.
- Full Text:
- Reviewed:
- Description: Amaranthus retroflexus L. (Amaranthaceae), Redroot pigweed, is native to North America, but has become a weed of agriculture worldwide. Previous research into competition with food crops found it significantly reduces yields. Additionally, taxonomy, biomass allocation, physiological responses to light intensity, water stress, elevated CO2, and herbicide resistance have been inves-tigated. To extend other research findings, we investigated growth and biomass yield in response to (i) soil moisture stress, and (ii) drought and elevated CO2. Additionally, we investigated seed germination rates following exposure to three elevated temperatures for two different time periods. Overall, moisture stress reduced plant height, stem diameter, and number of leaves. Elevated CO2 (700 ppm) appeared to reduce negative impacts of drought on biomass productivity. Heating seeds at 120◦C and above for either 180 or 300 s significantly reduced germination rate. These results inform an understanding of potential responses of A. retroflexus to future climate change and will be used to predict future occurrence of this weed. The finding that exposing seeds to high temperatures retards germination suggests fire could be used to prevent seed germination from soil seed banks, particularly in no-till situations, and therefore may be used to address infestations or prevent further spread of this weed. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. **Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliates “Sandra Weller, Singarayer Florentine, Amali Welgama, Aakansha Chadha, Chrisopher Turville" are provided in this record**
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.
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.
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.
Detecting the seeds of Nassella neesiana in large round hay bales, by means of non-destructive core sampling
- Weller, Sandra, Florentine, Singarayer, Sillitoe, Jim, Grech, Charles, McLaren, David, Chauhan, Bhagirath
- Authors: Weller, Sandra , Florentine, Singarayer , Sillitoe, Jim , Grech, Charles , McLaren, David , Chauhan, Bhagirath
- Date: 2015
- Type: Text , Journal article
- Relation: Plos One Vol. 10, no. 9 (2015), p.
- Full Text:
- Reviewed:
- Description: In the last three decades or so there has been a significant increase in fodder trading, both in terms of the quantity of fodder traded and in terms of its economic value to the industry. Often, this fodder type may be supplied free of charge to graziers in distress due to circumstances that follow natural disasters such as bushfires, drought, and flood. However, because of the obvious urgency arising from these situations, it is suspected that much relief fodder may unintentionally pose an elevated risk for dispersal of weeds since it may be supplied from pasture not normally used for trade in fodder, and therefore is of unknown quality. Previous destructive method to detect weed propagules in bales of fodder are cumbersome, time consuming and of limited ecological and statistical value. Therefore, objective of this paper was to development of a convenient method to assess round pasture hay bales for the presence of weed propagules, to prevent unintentional spread of noxious species in hay bales. To examine this objective known quantity of seeds were added in a series of distributions to bales of seed free pasture hay, and a positive correlation for the amount of seed added per bale with that recovered in core samples was observed. Whilst the number of seeds detected per bale varied according to the distribution of seeds within the bales and the number of cores analysed, the absolute detection of seeds suggests that this sampling method is worthy of further examination. In addition, a pragmatic estimation of bale remnants after stock feeding has been investigated to more closely estimate the potential size of the remaining seed bank. The authors propose that development of this approach is timely, in the light of future climatic uncertainty driving extreme weather events that increase the need for relief fodder, which can be a potential vector for the spread of noxious weed seeds.
- Authors: Weller, Sandra , Florentine, Singarayer , Sillitoe, Jim , Grech, Charles , McLaren, David , Chauhan, Bhagirath
- Date: 2015
- Type: Text , Journal article
- Relation: Plos One Vol. 10, no. 9 (2015), p.
- Full Text:
- Reviewed:
- Description: In the last three decades or so there has been a significant increase in fodder trading, both in terms of the quantity of fodder traded and in terms of its economic value to the industry. Often, this fodder type may be supplied free of charge to graziers in distress due to circumstances that follow natural disasters such as bushfires, drought, and flood. However, because of the obvious urgency arising from these situations, it is suspected that much relief fodder may unintentionally pose an elevated risk for dispersal of weeds since it may be supplied from pasture not normally used for trade in fodder, and therefore is of unknown quality. Previous destructive method to detect weed propagules in bales of fodder are cumbersome, time consuming and of limited ecological and statistical value. Therefore, objective of this paper was to development of a convenient method to assess round pasture hay bales for the presence of weed propagules, to prevent unintentional spread of noxious species in hay bales. To examine this objective known quantity of seeds were added in a series of distributions to bales of seed free pasture hay, and a positive correlation for the amount of seed added per bale with that recovered in core samples was observed. Whilst the number of seeds detected per bale varied according to the distribution of seeds within the bales and the number of cores analysed, the absolute detection of seeds suggests that this sampling method is worthy of further examination. In addition, a pragmatic estimation of bale remnants after stock feeding has been investigated to more closely estimate the potential size of the remaining seed bank. The authors propose that development of this approach is timely, in the light of future climatic uncertainty driving extreme weather events that increase the need for relief fodder, which can be a potential vector for the spread of noxious weed seeds.
The need for speed: Timely prevention of the dispersal of noxious weeds in relief fodder using efficient sampling procedures
- Weller, Sandra, Florentine, Singarayer, Sillitoe, Jim, Grech, Charles, McLaren, David, Chauhan, Bhagirath
- Authors: Weller, Sandra , Florentine, Singarayer , Sillitoe, Jim , Grech, Charles , McLaren, David , Chauhan, Bhagirath
- Date: 2015
- Type: Text , Journal article
- Relation: Crop Protection Vol. 70, no. (2015), p. 21-27
- Full Text:
- Reviewed:
- Description: Invasive and noxious weeds are well known as a pervasive problem, imposing significant economic burdens on all areas of agriculture. Whilst there are multiple possible pathways of weed dispersal in this industry, of particular interest to this discussion is the unintended dispersal of weed seeds within fodder. During periods of drought or following natural disasters such as wild fire or flood, there arises the urgent need for 'relief' fodder to ensure survival and recovery of livestock. In emergency situations, relief fodder may be sourced from widely dispersed geographic regions, and some of these regions may be invaded by an extensive variety of weeds that are both exotic and detrimental to the intended destination for the fodder. Pasture hay is a common source of relief fodder and it typically consists of a mixture of grassy and broadleaf species that may include noxious weeds. When required urgently, pasture hay for relief fodder can be cut, baled, and transported over long distances in a short period of time, with little opportunity for prebaling inspection. It appears that, at the present time, there has been little effort towards rapid testing of bales, post-baling, for the presence of noxious weeds, as a measure to prevent dispersal of seeds. Published studies have relied on the analysis of relatively small numbers of bales, tested to destruction, in order to reveal seed species for identification and enumeration. The development of faster, more reliable, and non-destructive sampling methods is essential to increase the fodder industry's capacity to prevent the dispersal of noxious weeds to previously unaffected locales.
- Authors: Weller, Sandra , Florentine, Singarayer , Sillitoe, Jim , Grech, Charles , McLaren, David , Chauhan, Bhagirath
- Date: 2015
- Type: Text , Journal article
- Relation: Crop Protection Vol. 70, no. (2015), p. 21-27
- Full Text:
- Reviewed:
- Description: Invasive and noxious weeds are well known as a pervasive problem, imposing significant economic burdens on all areas of agriculture. Whilst there are multiple possible pathways of weed dispersal in this industry, of particular interest to this discussion is the unintended dispersal of weed seeds within fodder. During periods of drought or following natural disasters such as wild fire or flood, there arises the urgent need for 'relief' fodder to ensure survival and recovery of livestock. In emergency situations, relief fodder may be sourced from widely dispersed geographic regions, and some of these regions may be invaded by an extensive variety of weeds that are both exotic and detrimental to the intended destination for the fodder. Pasture hay is a common source of relief fodder and it typically consists of a mixture of grassy and broadleaf species that may include noxious weeds. When required urgently, pasture hay for relief fodder can be cut, baled, and transported over long distances in a short period of time, with little opportunity for prebaling inspection. It appears that, at the present time, there has been little effort towards rapid testing of bales, post-baling, for the presence of noxious weeds, as a measure to prevent dispersal of seeds. Published studies have relied on the analysis of relatively small numbers of bales, tested to destruction, in order to reveal seed species for identification and enumeration. The development of faster, more reliable, and non-destructive sampling methods is essential to increase the fodder industry's capacity to prevent the dispersal of noxious weeds to previously unaffected locales.
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