Effect of selected environmental factors on the seed germination of the invasive species Polygala myrtifolia (Polygalaceae) in Australia
- Roberts, Natalie, Moloney, Katrina, Monie, Kristin, Florentine, Singarayer
- Authors: Roberts, Natalie , Moloney, Katrina , Monie, Kristin , Florentine, Singarayer
- Date: 2023
- Type: Text , Journal article
- Relation: Australian Journal of Botany Vol. 71, no. 6 (2023), p. 286-295
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- Description: Context. Polygala myrtifolia L. has become a significant environmental weed in Australia, where it has invaded coastal ecosystems in temperate regions and there is a high risk of extensive further spread. Knowledge of seed-germination behaviour is essential to understand the potential future impact of this species. Aims. We investigated the effects of selected environmental factors and dormancy on P. myrtifolia seed germination and emergence to improve management strategies. Methods. Seeds were exposed to light, temperature, pH, salinity, osmotic potential and burial depth treatments to assess germination responses, dormancy and viability. Key results. Non-dormant seeds readily germinated to high percentages (93.0–95.0%) under specific day–night temperatures of 25°C–15°C regardless of light conditions and across all soil pH (75.0–100.0%). Salinities were tolerated up to 100 mM NaCl (70.0% germination) before sharply declining. Germination reduced from 98.3% to 40.0% at osmotic potentials of
- Authors: Roberts, Natalie , Moloney, Katrina , Monie, Kristin , Florentine, Singarayer
- Date: 2023
- Type: Text , Journal article
- Relation: Australian Journal of Botany Vol. 71, no. 6 (2023), p. 286-295
- Full Text:
- Reviewed:
- Description: Context. Polygala myrtifolia L. has become a significant environmental weed in Australia, where it has invaded coastal ecosystems in temperate regions and there is a high risk of extensive further spread. Knowledge of seed-germination behaviour is essential to understand the potential future impact of this species. Aims. We investigated the effects of selected environmental factors and dormancy on P. myrtifolia seed germination and emergence to improve management strategies. Methods. Seeds were exposed to light, temperature, pH, salinity, osmotic potential and burial depth treatments to assess germination responses, dormancy and viability. Key results. Non-dormant seeds readily germinated to high percentages (93.0–95.0%) under specific day–night temperatures of 25°C–15°C regardless of light conditions and across all soil pH (75.0–100.0%). Salinities were tolerated up to 100 mM NaCl (70.0% germination) before sharply declining. Germination reduced from 98.3% to 40.0% at osmotic potentials of
The response of Nassella trichotoma (serrated tussock) seeds and seedlings to different levels of fire intensity
- Humphries, Talia, Florentine, Singarayer
- Authors: Humphries, Talia , Florentine, Singarayer
- Date: 2023
- Type: Text , Journal article
- Relation: Australian Journal of Botany Vol. 71, no. 4 (2023), p. 188-198
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- Description: Context Fire is an important disturbance regime in grassland communities, since it is responsible for stimulating the regeneration of many species and for maintaining levels of biodiversity. When invasive plants, such as Nassella trichotoma, establish and become widespread in a grassland community, these important fire events can be altered in intensity and frequency, which means that they are able to facilitate the establishment of the exotic species. Therefore, before fire can be recommended as a suitable control technique for invasive species, or alternatively to be integrated into grassland restoration programs, understanding the response of the seeds of exotic species to high temperatures, such as those experienced during a fire, should be well understood. Aims Our aim was to identify their response to a gradient of temperatures associated with different levels of fire intensity. We examined how increased duration of exposure affects their response, and whether seed age or seed moisture content affect the germination response of this species. Methods To gain a fuller understanding of the fire response of N. trichotoma’s seedbank, seeds were collected in 2016, 2017, 2018 and 2019 and then stored until the commencement of the experiments in 2020. Selected seeds were first subjected to an increasing temperature gradient (80°C, 100°C, 120°C, 140°C, and a control), and an increasing duration of exposure (of 1, 3, 6, and 9 min). In the second experiment, one population was selected to test these same temperatures and duration of exposure after the seeds were hydrated to 15%, 50%, or 95%. Last, seedlings were grown for 3 months under glasshouse conditions and then exposed to increasing temperatures (20°C, 60°C, 80°C, 100°C, and 120°C), and an increasing duration of exposure (3, 6, and 9 min). The seedlings were assessed 2 weeks after the heat exposure for signs of damage. Key results It was found that increased temperatures and duration of exposure had a subtle negative effect on germination parameters, including reduced total germination and increased time to 50% germination. The 140°C treatment was seen to be a significant threshold because it killed all the seeds at any duration of exposure. A significant difference among the ages of each seed lot was observed to be a factor on the tested germination metrics, with the oldest tested population (2016) demonstrating the highest germination percentage, uniformity, and rate. Seed germination percentage was significantly reduced for seeds hydrated to 95% compared with the control treatment, whereas no significant difference was observed for the seeds hydrated to 15% and 50%. For the heat treatment of the seedlings, damage to the leaves was observed in the 80°C, 100°C, and 120°C treatments, with some plants in the 120°C treatment experiencing extensive damage prior to resprouting. No seedlings were killed at the tested temperatures. Conclusions Results of this study indicated that fire may be a useful tool for reducing seedbank density by killing a high proportion of the seeds on the soil surface, or located within the top 1 cm of the soil profile, but not for seeds buried more deeply. Efficacy of fire on surface and shallow-buried seeds is improved with high seed moisture content however, these seeds buried below this depth are still protected by the soil from the lethal effects of temperature. Implications Fire implemented before seed set could be used to effectively kill a large proportion of N. trichotoma seeds. However, for more comprehensive control, it is recommended that chemical treatment is integrated with the fire treatment to improve the overall control efficiency.
- Authors: Humphries, Talia , Florentine, Singarayer
- Date: 2023
- Type: Text , Journal article
- Relation: Australian Journal of Botany Vol. 71, no. 4 (2023), p. 188-198
- Full Text:
- Reviewed:
- Description: Context Fire is an important disturbance regime in grassland communities, since it is responsible for stimulating the regeneration of many species and for maintaining levels of biodiversity. When invasive plants, such as Nassella trichotoma, establish and become widespread in a grassland community, these important fire events can be altered in intensity and frequency, which means that they are able to facilitate the establishment of the exotic species. Therefore, before fire can be recommended as a suitable control technique for invasive species, or alternatively to be integrated into grassland restoration programs, understanding the response of the seeds of exotic species to high temperatures, such as those experienced during a fire, should be well understood. Aims Our aim was to identify their response to a gradient of temperatures associated with different levels of fire intensity. We examined how increased duration of exposure affects their response, and whether seed age or seed moisture content affect the germination response of this species. Methods To gain a fuller understanding of the fire response of N. trichotoma’s seedbank, seeds were collected in 2016, 2017, 2018 and 2019 and then stored until the commencement of the experiments in 2020. Selected seeds were first subjected to an increasing temperature gradient (80°C, 100°C, 120°C, 140°C, and a control), and an increasing duration of exposure (of 1, 3, 6, and 9 min). In the second experiment, one population was selected to test these same temperatures and duration of exposure after the seeds were hydrated to 15%, 50%, or 95%. Last, seedlings were grown for 3 months under glasshouse conditions and then exposed to increasing temperatures (20°C, 60°C, 80°C, 100°C, and 120°C), and an increasing duration of exposure (3, 6, and 9 min). The seedlings were assessed 2 weeks after the heat exposure for signs of damage. Key results It was found that increased temperatures and duration of exposure had a subtle negative effect on germination parameters, including reduced total germination and increased time to 50% germination. The 140°C treatment was seen to be a significant threshold because it killed all the seeds at any duration of exposure. A significant difference among the ages of each seed lot was observed to be a factor on the tested germination metrics, with the oldest tested population (2016) demonstrating the highest germination percentage, uniformity, and rate. Seed germination percentage was significantly reduced for seeds hydrated to 95% compared with the control treatment, whereas no significant difference was observed for the seeds hydrated to 15% and 50%. For the heat treatment of the seedlings, damage to the leaves was observed in the 80°C, 100°C, and 120°C treatments, with some plants in the 120°C treatment experiencing extensive damage prior to resprouting. No seedlings were killed at the tested temperatures. Conclusions Results of this study indicated that fire may be a useful tool for reducing seedbank density by killing a high proportion of the seeds on the soil surface, or located within the top 1 cm of the soil profile, but not for seeds buried more deeply. Efficacy of fire on surface and shallow-buried seeds is improved with high seed moisture content however, these seeds buried below this depth are still protected by the soil from the lethal effects of temperature. Implications Fire implemented before seed set could be used to effectively kill a large proportion of N. trichotoma seeds. However, for more comprehensive control, it is recommended that chemical treatment is integrated with the fire treatment to improve the overall control efficiency.
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
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- 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.
Allelopathic potential of the newly emerging weed solanum mauritianum Scop. (solanaceae) in the wet tropics of north-east Queensland
- Florentine, Singarayer, Westbrooke, Martin
- Authors: Florentine, Singarayer , Westbrooke, Martin
- Date: 2003
- Type: Text , Journal article
- Relation: Plant Protection Quarterly Vol. 18, no. 1 (2003), p. 23-25
- Full Text:
- Reviewed:
- Description: Solanum mauritianum
- Description: C1
- Description: 2003004172
- Authors: Florentine, Singarayer , Westbrooke, Martin
- Date: 2003
- Type: Text , Journal article
- Relation: Plant Protection Quarterly Vol. 18, no. 1 (2003), p. 23-25
- Full Text:
- Reviewed:
- Description: Solanum mauritianum
- Description: C1
- Description: 2003004172
Flowering, fruiting, germination and seed despersal of the newly emerging weed Solanum mauritianum Scop. (solanaceae) in the wet tropics of north Queensland
- Florentine, Singarayer, Westbrooke, Martin, Craig, M.
- Authors: Florentine, Singarayer , Westbrooke, Martin , Craig, M.
- Date: 2003
- Type: Text , Journal article
- Relation: Plant Protection Quarterly Vol. 18, no. 3 (2003), p. 116-120
- Full Text:
- Reviewed:
- Description: Solanum mauritianum (wild tobacco) has recently become a weed of major concern in some agricultural production areas, and tropical rainforest restoration sites, of the Atherton Tablelands, north Queensland. Until recently, little was known about the ecology of this species. A study was conducted to examine: Ii) the flowering, fruiting pattern, (ii) seed germination pattern, (iii) density of soil stored seed bank, and (iv) potential avian seed dispersers of S. mauritianum. Flowering and fruiting patterns were studied on-randomly selected plants within the study site over a period of 35 days. A germination study was performed on green (unripe) and yellow (ripe) fruits with seeds from green fruits germinating faster than seeds collected from yellow fruits. The density of genninable seeds in the soil seed bank was determined from 94 samples collected beneath the canopy of 24 randomly selected S. mauritianum plants. Of seedlings Ihat germinated, 73% were S. mauritianum and seedling density of S. mauritiallum averaged 16 000 seedlings per hectare. To determine the role of birds in the dispersal of S. mauritianum seeds, observations were made of all birds visiting eleven fruit-bearing plants. To examine the bird's excrement, birds were captured in mist-nets, their excrement collected and any seeds present identified. A total of 340 seeds from 15 plant species were obtained. Four tropical rainforest birds (Australian king parrots (
- Description: C1
- Description: 2003000548
- Authors: Florentine, Singarayer , Westbrooke, Martin , Craig, M.
- Date: 2003
- Type: Text , Journal article
- Relation: Plant Protection Quarterly Vol. 18, no. 3 (2003), p. 116-120
- Full Text:
- Reviewed:
- Description: Solanum mauritianum (wild tobacco) has recently become a weed of major concern in some agricultural production areas, and tropical rainforest restoration sites, of the Atherton Tablelands, north Queensland. Until recently, little was known about the ecology of this species. A study was conducted to examine: Ii) the flowering, fruiting pattern, (ii) seed germination pattern, (iii) density of soil stored seed bank, and (iv) potential avian seed dispersers of S. mauritianum. Flowering and fruiting patterns were studied on-randomly selected plants within the study site over a period of 35 days. A germination study was performed on green (unripe) and yellow (ripe) fruits with seeds from green fruits germinating faster than seeds collected from yellow fruits. The density of genninable seeds in the soil seed bank was determined from 94 samples collected beneath the canopy of 24 randomly selected S. mauritianum plants. Of seedlings Ihat germinated, 73% were S. mauritianum and seedling density of S. mauritiallum averaged 16 000 seedlings per hectare. To determine the role of birds in the dispersal of S. mauritianum seeds, observations were made of all birds visiting eleven fruit-bearing plants. To examine the bird's excrement, birds were captured in mist-nets, their excrement collected and any seeds present identified. A total of 340 seeds from 15 plant species were obtained. Four tropical rainforest birds (Australian king parrots (
- Description: C1
- Description: 2003000548
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