Aims Seed dormancy and the soil seed bank are crucial to plant regeneration strategy,especially in semiarid ecosystems with unpredictable precipi-tation.the aim of this study was to investigate how seed dormancy is co...Aims Seed dormancy and the soil seed bank are crucial to plant regeneration strategy,especially in semiarid ecosystems with unpredictable precipi-tation.the aim of this study was to investigate how seed dormancy is controlled by environmental factors and how it is correlated with the soil seed bank and regeneration of the perennial legume Oxytropis race-mosa,a dominant perennial herb in Mu Us Sandland of semiarid China.Methods Germination and imbibition experiments on fresh intact and scarified seeds of O.racemosa were used to identify physical dormancy(PY)in seeds of this species.Soil seed bank dynamics,timing of seedling emer-gence and the fate of buried seeds in the natural habitat were investigated.Important Findings PY was broken by mechanical scarification or wet heat/ice water cycles but not solely by dry heat or wet heat treatment.the soil seed bank exhibited seasonal changes in the number of seeds,which was highest in September and lowest in July.Seeds buried at different sand depths gradually lost dormancy;20-42%of the seeds remained dormant after 20 months of burial.Dormancy break occurs grad-ually throughout the year.Our results indicate that O.racemosa exhibits hardcoatedness heterogeneity that spreads germination of a seed cohort between seasons and years in the semiarid environ-ment,where the amount of precipitation during the growing season is highly variable.展开更多
Mooseer （Allium hirtifolium Boiss.） is bulbous perennial herb widely used in pharmaceutical and food industry in Iran. We studied germination of mooseer seeds in two separate experiments. In the first experiment, we...Mooseer （Allium hirtifolium Boiss.） is bulbous perennial herb widely used in pharmaceutical and food industry in Iran. We studied germination of mooseer seeds in two separate experiments. In the first experiment, we evaluated four treatments： sulfuric acid scarification, sandpaper scarification, cold stratification, and gibberellic acid （GA3） application. In the second experiment, we evaluated combinations of these treatments. All treatments in the first experiment had no effect on seed germination, suggesting that mooseer seeds have physical and physiological dormancy. In the second experiment, the highest germina- tion percentage （86.6%） was observed after five minutes scarification with sulfuric acid （75% v/v）, followed by 60 days of cold stratification. Duration of sulfuric acid scarification （5, 10, and 20 min） did not affect germination rates, but increasing duration of cold stratification （from 15 to 60 days）, increased germination from 28.3% to 86.6%. Our study showed that mooseer seeds have both physical and physiological dormancy.展开更多
Aims The study of the adaptive potential of the germination patterns of invading species enables us to identify some traits linked with their capacity to colonize new sites,and to gain a better understanding of their ...Aims The study of the adaptive potential of the germination patterns of invading species enables us to identify some traits linked with their capacity to colonize new sites,and to gain a better understanding of their area of distribution.The aim of this study is to determine the germination pattern of Ulex europaeus,a cosmopolitan invasive species,in relation to temperature and to explore its potential evolu-tion and invasiveness in a tropical region,following its introduction from Europe.Methods We studied the germination pattern of U.europaeus(the com-mon gorse)to test both physical dormancy and germination capacity within the range of temperatures found in the native and invasive regions.To understand its germination pattern and its evolution,the rate and the speed of germination,as well as the percentage of seeds that became mouldy during the experi-ment,have been compared between a native habitat,France and a habitat into which it has been introduced,the tropical island of La Reunion.Important Findings The results show that gorse seeds germinate in large quantities,pos-sess the ability to germinate under a wide range of temperatures and they confirm the physical dormancy of the seeds(caused by seed coat impermeability).The decrease in germination from 25℃ upwards,coupled with an increase in the rate of moulding help to explain its restricted distribution at altitude in tropical environments.For scari-fied seeds,we have not detected any difference between the two regions,neither in the percentage of germinated seeds,nor in the per-centage of mouldy seeds.However,seeds from Reunion germinate faster at 20℃ than seeds from France and a greater number of seeds from Reunion are able to germinate without scarification(10-60%for Reunion versus 0-10%for France).These results suggest that while preserving the advantages of the native habitat,in Reunion gorse develops a strategy which favours the rapid occupation of new sites.展开更多
Aims In dry tropical forests,herbaceous species may have dormancy mechanisms and form persistent and transient seed banks in the soil.Evolutionarily acquired,these mechanisms are efficient for the establishment and su...Aims In dry tropical forests,herbaceous species may have dormancy mechanisms and form persistent and transient seed banks in the soil.Evolutionarily acquired,these mechanisms are efficient for the establishment and survival of these herbs,especially in forests with unpredictable climates,such as the Caatinga.Thus,our objective was to verify whether the studied herbaceous species adopt the physical dormancy mechanism and how these natural barriers are overcome,to understand the temporal dynamics existing in the soil seed bank from a Brazilian dry tropical forest.Methods Seeds of five native herbaceous species from the Caatinga forests were selected and submitted to pre-germinative treatments for verifying the presence of physical dormancy.We collected soil samples in the rainy and dry seasons for four consecutive years and monitored the emergence of the selected herbaceous in the greenhouse.We verified the differences in germination and seed bank emergence in the soil by generalized linear models.Important Findings The presence and absence of physical dormancy were observed in seeds from Caatinga herbaceous species.We found intraspecific and interspecific differences in the herbaceous emergence from soil seed banks between years and climatic seasons.In perennial herbs,consecutive lack of emergence between seasons and years was frequent,which suggests a direct relationship with the mechanism of physical dormancy and the environmental conditions necessary to overcome integument barriers.In these species,seed dimorphism and dormancy may confer additional advantages to their survival.Moreover,presenting intermediate levels of physical dormancy in an annual species may be an evolutionary adjustment to rainfall unpredictability.In contrast,we found that the annual herb without dormancy is more sensitive to seasonal and interannual climate changes,as evidenced by the increase and significant reduction of its emergence in the soil seed bank.These differences acquired evolutionarily are advantageous for the establishment of herbaceous populations,mainly in semiarid regions with an unpredictable climate.展开更多
基金This research was supported by the Key Basic Research and Development Plan of P.R.China(2016YFC050080502)the National Natural Science Foundation of P.R.China(31370705,31570416).
文摘Aims Seed dormancy and the soil seed bank are crucial to plant regeneration strategy,especially in semiarid ecosystems with unpredictable precipi-tation.the aim of this study was to investigate how seed dormancy is controlled by environmental factors and how it is correlated with the soil seed bank and regeneration of the perennial legume Oxytropis race-mosa,a dominant perennial herb in Mu Us Sandland of semiarid China.Methods Germination and imbibition experiments on fresh intact and scarified seeds of O.racemosa were used to identify physical dormancy(PY)in seeds of this species.Soil seed bank dynamics,timing of seedling emer-gence and the fate of buried seeds in the natural habitat were investigated.Important Findings PY was broken by mechanical scarification or wet heat/ice water cycles but not solely by dry heat or wet heat treatment.the soil seed bank exhibited seasonal changes in the number of seeds,which was highest in September and lowest in July.Seeds buried at different sand depths gradually lost dormancy;20-42%of the seeds remained dormant after 20 months of burial.Dormancy break occurs grad-ually throughout the year.Our results indicate that O.racemosa exhibits hardcoatedness heterogeneity that spreads germination of a seed cohort between seasons and years in the semiarid environ-ment,where the amount of precipitation during the growing season is highly variable.
文摘Mooseer （Allium hirtifolium Boiss.） is bulbous perennial herb widely used in pharmaceutical and food industry in Iran. We studied germination of mooseer seeds in two separate experiments. In the first experiment, we evaluated four treatments： sulfuric acid scarification, sandpaper scarification, cold stratification, and gibberellic acid （GA3） application. In the second experiment, we evaluated combinations of these treatments. All treatments in the first experiment had no effect on seed germination, suggesting that mooseer seeds have physical and physiological dormancy. In the second experiment, the highest germina- tion percentage （86.6%） was observed after five minutes scarification with sulfuric acid （75% v/v）, followed by 60 days of cold stratification. Duration of sulfuric acid scarification （5, 10, and 20 min） did not affect germination rates, but increasing duration of cold stratification （from 15 to 60 days）, increased germination from 28.3% to 86.6%. Our study showed that mooseer seeds have both physical and physiological dormancy.
文摘Aims The study of the adaptive potential of the germination patterns of invading species enables us to identify some traits linked with their capacity to colonize new sites,and to gain a better understanding of their area of distribution.The aim of this study is to determine the germination pattern of Ulex europaeus,a cosmopolitan invasive species,in relation to temperature and to explore its potential evolu-tion and invasiveness in a tropical region,following its introduction from Europe.Methods We studied the germination pattern of U.europaeus(the com-mon gorse)to test both physical dormancy and germination capacity within the range of temperatures found in the native and invasive regions.To understand its germination pattern and its evolution,the rate and the speed of germination,as well as the percentage of seeds that became mouldy during the experi-ment,have been compared between a native habitat,France and a habitat into which it has been introduced,the tropical island of La Reunion.Important Findings The results show that gorse seeds germinate in large quantities,pos-sess the ability to germinate under a wide range of temperatures and they confirm the physical dormancy of the seeds(caused by seed coat impermeability).The decrease in germination from 25℃ upwards,coupled with an increase in the rate of moulding help to explain its restricted distribution at altitude in tropical environments.For scari-fied seeds,we have not detected any difference between the two regions,neither in the percentage of germinated seeds,nor in the per-centage of mouldy seeds.However,seeds from Reunion germinate faster at 20℃ than seeds from France and a greater number of seeds from Reunion are able to germinate without scarification(10-60%for Reunion versus 0-10%for France).These results suggest that while preserving the advantages of the native habitat,in Reunion gorse develops a strategy which favours the rapid occupation of new sites.
基金supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico-Brazil(CNPQ 4652712914-6APQ 0083.2-05/15).
文摘Aims In dry tropical forests,herbaceous species may have dormancy mechanisms and form persistent and transient seed banks in the soil.Evolutionarily acquired,these mechanisms are efficient for the establishment and survival of these herbs,especially in forests with unpredictable climates,such as the Caatinga.Thus,our objective was to verify whether the studied herbaceous species adopt the physical dormancy mechanism and how these natural barriers are overcome,to understand the temporal dynamics existing in the soil seed bank from a Brazilian dry tropical forest.Methods Seeds of five native herbaceous species from the Caatinga forests were selected and submitted to pre-germinative treatments for verifying the presence of physical dormancy.We collected soil samples in the rainy and dry seasons for four consecutive years and monitored the emergence of the selected herbaceous in the greenhouse.We verified the differences in germination and seed bank emergence in the soil by generalized linear models.Important Findings The presence and absence of physical dormancy were observed in seeds from Caatinga herbaceous species.We found intraspecific and interspecific differences in the herbaceous emergence from soil seed banks between years and climatic seasons.In perennial herbs,consecutive lack of emergence between seasons and years was frequent,which suggests a direct relationship with the mechanism of physical dormancy and the environmental conditions necessary to overcome integument barriers.In these species,seed dimorphism and dormancy may confer additional advantages to their survival.Moreover,presenting intermediate levels of physical dormancy in an annual species may be an evolutionary adjustment to rainfall unpredictability.In contrast,we found that the annual herb without dormancy is more sensitive to seasonal and interannual climate changes,as evidenced by the increase and significant reduction of its emergence in the soil seed bank.These differences acquired evolutionarily are advantageous for the establishment of herbaceous populations,mainly in semiarid regions with an unpredictable climate.
