[Objective] The aim was to study the damage and the mechanism of combined pollution of Pb and Cd on rice growth,yield and quality of rice. [Method]Effects of combined pollution of Pb and Cd on the growth and yield of ...[Objective] The aim was to study the damage and the mechanism of combined pollution of Pb and Cd on rice growth,yield and quality of rice. [Method]Effects of combined pollution of Pb and Cd on the growth and yield of rice were studied by pot experiment with cultivating rice. [Result] Pb and Cd could promote rice growth at low concentration while inhibit plant height at high concentration; Pb and Cd stress reduced the number of rice tillers significantly,with the increasing of stress concentration,the decrease amplitude of the number of tillers was greater; the panicle per pot,seed setting rate,1 000-grain weight and yield of rice were reduced significantly by Pb and Cd stress,the grain number per panicle decreased significantly under low concentration of Pb and Cd but increased significantly under high concentration; the brown rice rate and milled rice rate increased significantly under low concentration of Pb and Cd while at high concentration of Pb and Cd,the both two reduced significantly,the head milled rice rate reduced significantly with the decreasing of concentration; The Pb and Cd content of grains were significantly positively related to the concentrations of Pb and Cd content in soil,it had excessively exceeded hygienic standard when the concentrations of Pb and Cd in soil were medium-high and the unqualified rate reached 333% and 122%. [Conclusion]The study had provided basis for the establishment of rice cultivation system in pollution areas.展开更多
The effects of major veins severing on morphological and physiological features of sweetgum （Liquidambar styraciflua L.） leaves were investigated by observing leaf color change and measuring leaf temperature, green/...The effects of major veins severing on morphological and physiological features of sweetgum （Liquidambar styraciflua L.） leaves were investigated by observing leaf color change and measuring leaf temperature, green/luminance （G/L） value of half-lobes, leaf stomata conductance, and water content in Yamaguchi University, Japan. The palmately veined leaves of sweetgum （Liquidambar styraciflua L.） were found more sensitive to the major vein severing than that of other species Major veins severing resulted in serious water stresses, as indicated by the persistent reddening and/or advanced reddening of local leaf, lower leaf stomatal conductance, and higher leaf temperature, etc. Severed leaf can be clearly divided into non-severed area, transitional area, and stressed area, which the three areas have different colours and temperature. The major vein barrier can also be seen clearly. The persistent reddening and advanced reddening seem consistent with the phenomenon of red crown top of some sweetgum trees and may have similar mechanism.展开更多
The capability ofScenedesmus obliquus to remove cations （K^＋, Na^＋, Ca^2＋, Mg^2＋） from saline- alkaline water was investigated at different salinities （0, 5, 10, 15, 20, 25） and carbonate alkalinities （0, 5, ...The capability ofScenedesmus obliquus to remove cations （K^＋, Na^＋, Ca^2＋, Mg^2＋） from saline- alkaline water was investigated at different salinities （0, 5, 10, 15, 20, 25） and carbonate alkalinities （0, 5, 10, 15, 20, 25, 30, 35 mmol/L）. K^＋, Na^＋, Ca^2＋, and Mg^2＋ in saline-alkaline water were efficiently removed by S. obliquus. The maximum removal of the cations （29.37 mg for K^＋, 185.85 mg for Na^＋, 23.07 mg for Ca^2＋, 66.14 mg for Mg^2＋） occurred at salinity 25. The maximum removal of K^＋ （2.28 mg）, Na＋ （6.62 mg）, Ca^2＋ （1.01 mg）, and Mg2＋ （0.62 mg） occurred at carbonate alkalinities of 25 mmol/L for K＊, 35 mmol/L for Na＋, 20 mmol/L for Ca2＋, and 25 mmol/L for Mf＋, respectively. Under a salinity stress, the concentration of Na＇ in S. obliquus increased significantly, while that of K~ decreased significantly. The concentrations of Ca^2＋ and Mg2＋ decreased as well. The ratios of K＋/Na~, Ca2＋/Na^＋, and Mg^2＋/Na^＋ were significantly lower in all salinity treatments than those of the control. Under alkaline stress, the concentrations of Nan and K＋ in S. obliquus decreased significantly and the ratios of K^＋/Na^＋, Ca2＋/Na^＋, and Mg^2＋/Na^＋ were significantly higher in all treatments than in the control. Moreover, the concentrations of Ca2＋ and Mg2＋ in S. obliquus at alkalinities of 5-10 mmol/L were significantly higher than those of the other treatments. The removal of Na＋ by S. obliquus mainly occurs through biosorption, and Mg^2＋ and Ca^2 ＋ were removed through both biosorption and bioaccumulation.展开更多
Research on the stress gradient hypothesis recognizes that positive(i.e. facilitative) and negative(i.e. competitive) plant interactions change in intensity and effect relative to abiotic stress experienced on a gradi...Research on the stress gradient hypothesis recognizes that positive(i.e. facilitative) and negative(i.e. competitive) plant interactions change in intensity and effect relative to abiotic stress experienced on a gradient. Motivated by observations of alpine treeline ecotones, we suggest that this switch in interaction could operate along a gradient of relative size of individual plants. We propose that as neighbors increase in size relative to a focal plant they improve the environment for that plant up to a critical point. After this critical point is surpassed, however, increasing relative size of neighbors will degrade the environment such that the net interaction intensity becomes negative. We developed a conceptual(not site or species specific) individual based model to simulate a single species with recruitment, growth, and mortality dependent on the environment mediated by the relative size of neighbors. Growth and size form a feedback. Simulation results show that the size gradient model produces metrics similar to that of a stress gradient model. Visualizations reveal that the size gradient model produces spatial patterns that are similar to the complex ones observed at alpine treelines. Size-mediated interaction could be a mechanism of the stress gradient hypothesis or it could operate independent of abiotic stress.展开更多
Evening primrose is a valuable oilseed crop with pharmaceutical and nutritional supplementation. Due to presence of valuable and rare gamma linolenic fatty acid, research on this plant has been started since 1970s by ...Evening primrose is a valuable oilseed crop with pharmaceutical and nutritional supplementation. Due to presence of valuable and rare gamma linolenic fatty acid, research on this plant has been started since 1970s by German and Britain scientists. Information about evening primrose cultivation is going to rise. Following to pervious studies the goal of this experiment was to clarify the effect of water and temperature stresses on seed yield and seed quality. Results showed that seed yield was significantly influenced by low temperature and water deficit. Plants grown under cold stress during rosette stage produced a lower seed yield than controls. The lowest seed yield was observed in the plants grown under permanent stress. Although the oil content of seeds was not influenced by low temperature stress, water stress strongly influenced the oil content and water stress stimulates oil accumulation. Like oil content, the GLA production seems to be increased under water stress conditions.展开更多
Salt stress is one of the most serious limiting factors for crop growth and production. This study was carried out to evaluate the effects of salt stress in four Mentha piperita L. varieties, in greenhouse conditions....Salt stress is one of the most serious limiting factors for crop growth and production. This study was carried out to evaluate the effects of salt stress in four Mentha piperita L. varieties, in greenhouse conditions. The seedlings were irrigated with 1/2 Hoagland nutrition solutions. Following 10 d of growth in the pots, the seedlings were subjected to salt stress with different concentrations of NaCl （0, 50 and 100 mM, respectively）. Responses of the mint varieties to salt stress were evaluated using some plant growth and physiological parameters, such as plant height, root length, shoot and root fresh and dry weight, and ion concentrations in leaves, such as Na, K, Ca and Cl. Salt stress caused reduction in physiological parameters. However, this reduction was significant at 100 mM NaCl compared to 50 mM NaCl. These two concentrations of NaCl increased Na and Cl contents in leaves. However, K and Ca contents were decreased with salinity. The results showed that Mentha piperita cv. Sewiss and Granada were found more tolerant to salt stress than cv. Marokko and Citaro.展开更多
We evaluated whether hydro-priming could improve vigour characteristics and seedling emergence of local maize （Zea mays L.） landraces compared to two commercial hybrids under water stress at the University of KwaZul...We evaluated whether hydro-priming could improve vigour characteristics and seedling emergence of local maize （Zea mays L.） landraces compared to two commercial hybrids under water stress at the University of KwaZulu-Natal, Pietermaritzburg. Seeds from local landraces were produced and characterized according to kernel colour, white （Land A） and purple （Land B）, and compared to two hybrids, SC701 and SR52, which are popular amongst local farmers. Seeds from each variety were soaked in water for 0 hours （unprimed or control）, 12 hours and 24 hours, and germinated in a germination chamber at 25 ℃ for 8 days. Parameters measured included final germination, mean germination time （MGT） and germination velocity index （GVI）. Seedling emergence was performed in seedling trays, using pine bark wetted to 25% or 75% of field capacity （FC）, for 21 days in a temperature-controlled glasshouse （25 ℃day; 15 ℃night; 60% RH）. Parameters measured included final emergence, mean emergence time （MET）, root and shoot lengths, and leaf area. Priming landraces for 12 and 24 hours reduced MGT by 9% and 7%, respectively, compared to 5% in hybrids for both 12 and 24 hours priming. GVI of landraces was improved by 40% following 12 hours of priming. GVI of hybrids was 11% and 7% slower than landraces after priming seeds for 12 and 24 hours, respectively. Priming seeds for 24 hours improved emergence at 25% FC. Priming seeds for 24 hours reduced MET for all varieties. Priming seeds for 12 and 24 hours increased leaf area by 33.8% and 29%, respectively. Hydro-priming seeds for 12 and 24 hours, respectively, improved GVI, reduced MGT and improved emergence and MET of maize landraces under water stress. Performance of hybrid seeds remains superior to that of landraces even after seed treatment to improve germination and vigour. The positive response of landraces to seed treatment, and improved performance under water stress conditions, suggest that there is a need to identify genes for vigour in landrace maize.展开更多
Toxicity of the different concentration of Cu^2＋ to the wheat seeding and its distribution in the plant were studied by solution culture. The results showed that： The correlation between the content of Cu^2＋ in med...Toxicity of the different concentration of Cu^2＋ to the wheat seeding and its distribution in the plant were studied by solution culture. The results showed that： The correlation between the content of Cu^2＋ in medium and the germination and growth of the seedlings is significant （P〈0.01）. The effect of Cu^2＋ to the germination, plant height, fresh weight, dried weight and the chlorophyll mount of the wheat seedling was stimulated under lower concentration of Cu^2＋ and was inhibited under higher concentration. With the increase of the Cu^2＋ concentration in the culture solution, the germination and growth of the seedlings was inhibited. The perfect positive correlation between the Cu^2＋ content in the plant and that in the culture solution was noted. Most of Cu^2＋ was concentrated in the root, and only a small amount was migrated to the aerial part of the wheat seedling. The sensitivity of each index to the Cu^2＋ concentration was ranked as follows： the Cu^2＋ content in the plant〉chlorophyll-a〉the ratio of chlorophyll-a to chlorophyll-b〉total chlorophyll〉plant height 〉germination〉fresh weight〉root elongation〉 chlorophyll-b 〉dried weight. The Cu^2＋ content in the wheat plant was the most sensitive index to the Cu^2＋ concentration in the culture solution.展开更多
The aims of this study were to investigate the effect of gradual water deficit stress on some phonological and morphological traits and grain yield of desi and kabuli chickpea cultivars. This study was carried out in ...The aims of this study were to investigate the effect of gradual water deficit stress on some phonological and morphological traits and grain yield of desi and kabuli chickpea cultivars. This study was carried out in 2007 and 2008, to evaluate responses of three chickpea cultivars （Hashem and Arman from kabuli and Pirooz from desi type） under well watering （I1： 70mm evaporation from class A pan）, gradual water deficit （12 and 13： 70→90→ 110→130 and 70→100→130mm evaporation from class A pan, respectively） and severe water stress （14： 130mm evaporation from class A pan）. Result showed that days to flowering and plant height were decreased, as water limitation increased. This reduction was significant under gradual water stress （I2 and I3） and Severe water deficit （I4）, compared with control （I1）. There were no significant differences in grain filling period and grain yield among I~, I2 and I3 irrigation treatments. No significant differences in days to physiologic maturity and number of sub branches were recorded among irrigation treatments. Interactions of year×cultivar for days to physiologic maturity, grain filling period and grain yield （P≤0.01） and for days to flowering and plant height （P≤0.05） were significant. The superiority of Arman in producing comparatively greater grain yield could be attributed to higher grain filling period of this cultivar in both years.展开更多
蒸散量量是地表水分循循环的重要分量量,与农业和生态系统的水水分需求密切相相关,是水资源规规划和管理必须考虑的重要要因素之一.虽虽然对湿润区作作物蒸散计算模型研究已经经相对比较成熟熟,但但由于干旱和半干旱区作物物蒸散量受干...蒸散量量是地表水分循循环的重要分量量,与农业和生态系统的水水分需求密切相相关,是水资源规规划和管理必须考虑的重要要因素之一.虽虽然对湿润区作作物蒸散计算模型研究已经经相对比较成熟熟,但但由于干旱和半干旱区作物物蒸散量受干旱旱胁迫的显著著影响,以往建建立的湿润区作作物蒸散模型和作作物系数并不适用对其作物物蒸散量的估算算,而目前对这一问题的研研究却十分有限限.利用位于黄土土高原典型半干旱区的"定西西干旱生态环环境综合科学试试验站"春小麦麦农田的蒸渗仪仪、蒸发皿、超声声涡动仪的观测资料及常规规气象观测资料料相结合,分析了该地区实际蒸散量与F AO推荐作物系数数估算的蒸散量之间的差异异性及其随干旱旱胁迫度的变化关系.研究究了该地区春小小麦参考蒸散量与与蒸发皿蒸发量比值和实际际蒸散量与蒸发发皿蒸发量比值随干旱胁迫迫度的变化特征征及春小麦作物系系数对干旱胁迫度的响应规规律,并对FA O推荐值的作作物系数进行了改进.分析发现,由于半干旱旱区作物蒸散受干旱胁迫影影响较大,FAO推荐作物系数数估算的蒸散散量与实际蒸散散量相差很显著著,实实际作物系数对干旱胁迫度度的依赖很强,,随干旱胁迫度增加显著减减少,但其敏感感性在干旱胁迫度度约达到0.7后明显降低.而且,改进的作物系数在作作物生长初期和和发育期远远低低于FAO的推荐荐值和Kumar修正值,改进进的作物系数估估算的春小麦蒸散量也明显显比后两者估算算的更接近实际观观测值,与观测测值线性拟合的系数为0.98,决定系数能能够达到0.455,标准误差也也仅为0.85 mm m,对对半干旱地区春小麦蒸散量量的估算效果比比较理想.展开更多
Drought can affect the growth and soil enzyme activities of invasive alien plants(IAPs).It is imperative to evaluate the competitive advantage of IAPs compared with that of the native species and the activities of soi...Drought can affect the growth and soil enzyme activities of invasive alien plants(IAPs).It is imperative to evaluate the competitive advantage of IAPs compared with that of the native species and the activities of soil enzymes under drought.This study aimed to evaluate the competitive advantage of the IAP Amaranthus spinosus that originated from tropical America compared with the native Chinese species A.tricolor and the activities of soil enzymes under drought.A competitive co-culture of A.spinosus and A.tricolor was established using a planting basin experiment.The two species were treated with different levels of drought,i.e.(i)the control;(ii)a light level of drought and(iii)a heavy level of drought.The functional traits,osmotic adjustment and the activities of antioxidant enzymes of the two species,as well as soil pH and electrical conductivity,contents of soil microbial biomass carbon and the activities of soil enzymes were determined.The relative competition intensity and relative dominance of A.spinosus were greater than those of A.tricolor under drought.Drought may provide an advantage to the competitive advantage of A.spinosus.Soil water-soluble salt content and sucrose hydrolytic power of A.spinosus were greater than those of A.tricolor under drought.The ability of A.spinosus to grow in soil with higher levels of water-soluble salt contents and sucrose hydrolytic power under drought may aid in its acquisition and utilization of nutrients.展开更多
Aims In estuarine salt-marshes,nitrate supply and soil salinity,which are known as two main environmental drivers,simultaneously affect the interspecific interactions between plant species.However,to date,their intera...Aims In estuarine salt-marshes,nitrate supply and soil salinity,which are known as two main environmental drivers,simultaneously affect the interspecific interactions between plant species.However,to date,their interactive effects on interspecific interactions have not been closely examined for salt-marsh plant species.Methods Juvenile plants of Suaeda salsa L.(Chenopodiaceae)and Scirpus planiculmis Fr.(Cyperaceae)were grown in rinsed river sand to conduct a greenhouse experiment with three treatment categories:interspecific interaction(mixed culture or monoculture),three salinity levels(1,50 and 100 mmol L^(-1))and three nitrate levels(0.5,5 and 10 mmol L^(-1)).First,height and biomass of all plants were measured.Then,the growth data,relative interaction index and competitive important index of the two species were analyzed.Important Findings The interspecific interactions between S.salsa and S.planiculmis were facilitation across the salinity gradients.The promotion of S.salsa growth with high nitrate supply did not enhance the facilitative effect of the species,especially at low salinity.However,high nitrate supply significantly shifted the interspecific interactions of S.planiculmis from facilitation to competition at high salinity.Our results suggest that excessive nitrate application changes the prediction of the stress-gradient hypothesis along a salinity gradient,leading to collapse of the two species coexistence in the salt-marshes.These findings make a contribution to the understanding of how S.salsa and S.planiculmis,as well as salt-marsh communities,respond to the human modification of estuarine nutritional levels.展开更多
Heterogeneity of soil salinity is a prominent environmental characteristic in the intertidal zone of estuaries,affecting the plant growth and the shift of biotic interactions in the salt marsh.This study aims to exami...Heterogeneity of soil salinity is a prominent environmental characteristic in the intertidal zone of estuaries,affecting the plant growth and the shift of biotic interactions in the salt marsh.This study aims to examine the interactive effects of a salinity gradient and salinity fluctuations on intraspecific interactions of a euhalophyte.We assessed the impact of daily fluctuating salinity on the outcome of intraspecific interactions by cultivating seeds of Suaeda salsa(Chenopodiaceae)in river sand.The experiment was conducted in a greenhouse with three treatments:daily salinity fluctuations(static and fluctuating salinity),a salinity gradient(200 and 400 mmol L^(−1))and three planting densities(1,2 and 4 plants/pot).First,height and biomass of plants were measured at both the start and end of the experiment.Then,the growth indexes and log response ratio of S.salsa were analyzed.The outcome of intraspecific interactions of S.salsa shifted from competition in low salinity to facilitation in high salinity,and high conspecific density strengthened the competition and facilitation intensities.Daily salinity fluctuation did not significantly affect the plant growth and the outcome of intraspecific interactions,but did have a significant influence on belowground biomass.Our results suggest that the stress-gradient hypothesis may apply to predicting the variation of the intraspecific relationship of a salt-tolerant species along a salinity gradient,and the magnitude of this variation is density dependent.These findings help us understand how individuals and populations of a euhalophyte species respond to the natural variation or human modification of salinity conditions.展开更多
Drought, flood, salinity, or a combination of these limits rice production. Several rice varieties are well known for their tolerance to specific abiotic stresses. We determined genetic relationship among 12 rice vari...Drought, flood, salinity, or a combination of these limits rice production. Several rice varieties are well known for their tolerance to specific abiotic stresses. We determined genetic relationship among 12 rice varieties including 9 tolerant to drought, flood, or salinity using inter-simple sequence repeat （ISSR） markers. Based on all markers, the nine tolerant varieties formed one cluster distinct from the cluster of three control varieties. The salt-tolerant varieties were closest to two flood-tolerant varieties, and together they were distinct from the drought-tolerant varieties. （GA）8YG was the most informative primer, showing the highest polymorphic information content （PIC） and resolving power （Rp）. The drought-, flood-, and salt-tolerant varieties grouped in three distinct clusters within the group of tolerant varieties, when （GA）8YG was used. Sabita was the only exception. The two aus varieties, Nagina22 and FR13A, were separated and grouped with the drought- and flood-tolerant varieties, respectively, hut they were together in dendrograms based on other primers. The results show that ISSR markers associated with （GA）sYG delineated the three groups of stress-tolerant varieties from each other and can be used to identify genes/new alleles associated with the three abiotic stresses in rice germplasm.展开更多
基金Supported by the Program of Ministry of Environmental Protection(200809093 )the Significant Science Planning Program of Guangdong Province (2008A080800028)~~
文摘[Objective] The aim was to study the damage and the mechanism of combined pollution of Pb and Cd on rice growth,yield and quality of rice. [Method]Effects of combined pollution of Pb and Cd on the growth and yield of rice were studied by pot experiment with cultivating rice. [Result] Pb and Cd could promote rice growth at low concentration while inhibit plant height at high concentration; Pb and Cd stress reduced the number of rice tillers significantly,with the increasing of stress concentration,the decrease amplitude of the number of tillers was greater; the panicle per pot,seed setting rate,1 000-grain weight and yield of rice were reduced significantly by Pb and Cd stress,the grain number per panicle decreased significantly under low concentration of Pb and Cd but increased significantly under high concentration; the brown rice rate and milled rice rate increased significantly under low concentration of Pb and Cd while at high concentration of Pb and Cd,the both two reduced significantly,the head milled rice rate reduced significantly with the decreasing of concentration; The Pb and Cd content of grains were significantly positively related to the concentrations of Pb and Cd content in soil,it had excessively exceeded hygienic standard when the concentrations of Pb and Cd in soil were medium-high and the unqualified rate reached 333% and 122%. [Conclusion]The study had provided basis for the establishment of rice cultivation system in pollution areas.
文摘The effects of major veins severing on morphological and physiological features of sweetgum （Liquidambar styraciflua L.） leaves were investigated by observing leaf color change and measuring leaf temperature, green/luminance （G/L） value of half-lobes, leaf stomata conductance, and water content in Yamaguchi University, Japan. The palmately veined leaves of sweetgum （Liquidambar styraciflua L.） were found more sensitive to the major vein severing than that of other species Major veins severing resulted in serious water stresses, as indicated by the persistent reddening and/or advanced reddening of local leaf, lower leaf stomatal conductance, and higher leaf temperature, etc. Severed leaf can be clearly divided into non-severed area, transitional area, and stressed area, which the three areas have different colours and temperature. The major vein barrier can also be seen clearly. The persistent reddening and advanced reddening seem consistent with the phenomenon of red crown top of some sweetgum trees and may have similar mechanism.
基金Supported by the Special Research Fund for the National Non-Profit Institutes(East China Sea Fisheries Research Institute)(Nos.2009M03,2007Z03)the National Special Research Fund for Non-Profit Sector(Agriculture)(No.200903001-0502)
文摘The capability ofScenedesmus obliquus to remove cations （K^＋, Na^＋, Ca^2＋, Mg^2＋） from saline- alkaline water was investigated at different salinities （0, 5, 10, 15, 20, 25） and carbonate alkalinities （0, 5, 10, 15, 20, 25, 30, 35 mmol/L）. K^＋, Na^＋, Ca^2＋, and Mg^2＋ in saline-alkaline water were efficiently removed by S. obliquus. The maximum removal of the cations （29.37 mg for K^＋, 185.85 mg for Na^＋, 23.07 mg for Ca^2＋, 66.14 mg for Mg^2＋） occurred at salinity 25. The maximum removal of K^＋ （2.28 mg）, Na＋ （6.62 mg）, Ca^2＋ （1.01 mg）, and Mg2＋ （0.62 mg） occurred at carbonate alkalinities of 25 mmol/L for K＊, 35 mmol/L for Na＋, 20 mmol/L for Ca2＋, and 25 mmol/L for Mf＋, respectively. Under a salinity stress, the concentration of Na＇ in S. obliquus increased significantly, while that of K~ decreased significantly. The concentrations of Ca^2＋ and Mg2＋ decreased as well. The ratios of K＋/Na~, Ca2＋/Na^＋, and Mg^2＋/Na^＋ were significantly lower in all salinity treatments than those of the control. Under alkaline stress, the concentrations of Nan and K＋ in S. obliquus decreased significantly and the ratios of K^＋/Na^＋, Ca2＋/Na^＋, and Mg^2＋/Na^＋ were significantly higher in all treatments than in the control. Moreover, the concentrations of Ca2＋ and Mg2＋ in S. obliquus at alkalinities of 5-10 mmol/L were significantly higher than those of the other treatments. The removal of Na＋ by S. obliquus mainly occurs through biosorption, and Mg^2＋ and Ca^2 ＋ were removed through both biosorption and bioaccumulation.
基金based upon work while an author served at the National Science Foundation(USA)
文摘Research on the stress gradient hypothesis recognizes that positive(i.e. facilitative) and negative(i.e. competitive) plant interactions change in intensity and effect relative to abiotic stress experienced on a gradient. Motivated by observations of alpine treeline ecotones, we suggest that this switch in interaction could operate along a gradient of relative size of individual plants. We propose that as neighbors increase in size relative to a focal plant they improve the environment for that plant up to a critical point. After this critical point is surpassed, however, increasing relative size of neighbors will degrade the environment such that the net interaction intensity becomes negative. We developed a conceptual(not site or species specific) individual based model to simulate a single species with recruitment, growth, and mortality dependent on the environment mediated by the relative size of neighbors. Growth and size form a feedback. Simulation results show that the size gradient model produces metrics similar to that of a stress gradient model. Visualizations reveal that the size gradient model produces spatial patterns that are similar to the complex ones observed at alpine treelines. Size-mediated interaction could be a mechanism of the stress gradient hypothesis or it could operate independent of abiotic stress.
文摘Evening primrose is a valuable oilseed crop with pharmaceutical and nutritional supplementation. Due to presence of valuable and rare gamma linolenic fatty acid, research on this plant has been started since 1970s by German and Britain scientists. Information about evening primrose cultivation is going to rise. Following to pervious studies the goal of this experiment was to clarify the effect of water and temperature stresses on seed yield and seed quality. Results showed that seed yield was significantly influenced by low temperature and water deficit. Plants grown under cold stress during rosette stage produced a lower seed yield than controls. The lowest seed yield was observed in the plants grown under permanent stress. Although the oil content of seeds was not influenced by low temperature stress, water stress strongly influenced the oil content and water stress stimulates oil accumulation. Like oil content, the GLA production seems to be increased under water stress conditions.
文摘Salt stress is one of the most serious limiting factors for crop growth and production. This study was carried out to evaluate the effects of salt stress in four Mentha piperita L. varieties, in greenhouse conditions. The seedlings were irrigated with 1/2 Hoagland nutrition solutions. Following 10 d of growth in the pots, the seedlings were subjected to salt stress with different concentrations of NaCl （0, 50 and 100 mM, respectively）. Responses of the mint varieties to salt stress were evaluated using some plant growth and physiological parameters, such as plant height, root length, shoot and root fresh and dry weight, and ion concentrations in leaves, such as Na, K, Ca and Cl. Salt stress caused reduction in physiological parameters. However, this reduction was significant at 100 mM NaCl compared to 50 mM NaCl. These two concentrations of NaCl increased Na and Cl contents in leaves. However, K and Ca contents were decreased with salinity. The results showed that Mentha piperita cv. Sewiss and Granada were found more tolerant to salt stress than cv. Marokko and Citaro.
文摘We evaluated whether hydro-priming could improve vigour characteristics and seedling emergence of local maize （Zea mays L.） landraces compared to two commercial hybrids under water stress at the University of KwaZulu-Natal, Pietermaritzburg. Seeds from local landraces were produced and characterized according to kernel colour, white （Land A） and purple （Land B）, and compared to two hybrids, SC701 and SR52, which are popular amongst local farmers. Seeds from each variety were soaked in water for 0 hours （unprimed or control）, 12 hours and 24 hours, and germinated in a germination chamber at 25 ℃ for 8 days. Parameters measured included final germination, mean germination time （MGT） and germination velocity index （GVI）. Seedling emergence was performed in seedling trays, using pine bark wetted to 25% or 75% of field capacity （FC）, for 21 days in a temperature-controlled glasshouse （25 ℃day; 15 ℃night; 60% RH）. Parameters measured included final emergence, mean emergence time （MET）, root and shoot lengths, and leaf area. Priming landraces for 12 and 24 hours reduced MGT by 9% and 7%, respectively, compared to 5% in hybrids for both 12 and 24 hours priming. GVI of landraces was improved by 40% following 12 hours of priming. GVI of hybrids was 11% and 7% slower than landraces after priming seeds for 12 and 24 hours, respectively. Priming seeds for 24 hours improved emergence at 25% FC. Priming seeds for 24 hours reduced MET for all varieties. Priming seeds for 12 and 24 hours increased leaf area by 33.8% and 29%, respectively. Hydro-priming seeds for 12 and 24 hours, respectively, improved GVI, reduced MGT and improved emergence and MET of maize landraces under water stress. Performance of hybrid seeds remains superior to that of landraces even after seed treatment to improve germination and vigour. The positive response of landraces to seed treatment, and improved performance under water stress conditions, suggest that there is a need to identify genes for vigour in landrace maize.
文摘Toxicity of the different concentration of Cu^2＋ to the wheat seeding and its distribution in the plant were studied by solution culture. The results showed that： The correlation between the content of Cu^2＋ in medium and the germination and growth of the seedlings is significant （P〈0.01）. The effect of Cu^2＋ to the germination, plant height, fresh weight, dried weight and the chlorophyll mount of the wheat seedling was stimulated under lower concentration of Cu^2＋ and was inhibited under higher concentration. With the increase of the Cu^2＋ concentration in the culture solution, the germination and growth of the seedlings was inhibited. The perfect positive correlation between the Cu^2＋ content in the plant and that in the culture solution was noted. Most of Cu^2＋ was concentrated in the root, and only a small amount was migrated to the aerial part of the wheat seedling. The sensitivity of each index to the Cu^2＋ concentration was ranked as follows： the Cu^2＋ content in the plant〉chlorophyll-a〉the ratio of chlorophyll-a to chlorophyll-b〉total chlorophyll〉plant height 〉germination〉fresh weight〉root elongation〉 chlorophyll-b 〉dried weight. The Cu^2＋ content in the wheat plant was the most sensitive index to the Cu^2＋ concentration in the culture solution.
文摘The aims of this study were to investigate the effect of gradual water deficit stress on some phonological and morphological traits and grain yield of desi and kabuli chickpea cultivars. This study was carried out in 2007 and 2008, to evaluate responses of three chickpea cultivars （Hashem and Arman from kabuli and Pirooz from desi type） under well watering （I1： 70mm evaporation from class A pan）, gradual water deficit （12 and 13： 70→90→ 110→130 and 70→100→130mm evaporation from class A pan, respectively） and severe water stress （14： 130mm evaporation from class A pan）. Result showed that days to flowering and plant height were decreased, as water limitation increased. This reduction was significant under gradual water stress （I2 and I3） and Severe water deficit （I4）, compared with control （I1）. There were no significant differences in grain filling period and grain yield among I~, I2 and I3 irrigation treatments. No significant differences in days to physiologic maturity and number of sub branches were recorded among irrigation treatments. Interactions of year×cultivar for days to physiologic maturity, grain filling period and grain yield （P≤0.01） and for days to flowering and plant height （P≤0.05） were significant. The superiority of Arman in producing comparatively greater grain yield could be attributed to higher grain filling period of this cultivar in both years.
文摘蒸散量量是地表水分循循环的重要分量量,与农业和生态系统的水水分需求密切相相关,是水资源规规划和管理必须考虑的重要要因素之一.虽虽然对湿润区作作物蒸散计算模型研究已经经相对比较成熟熟,但但由于干旱和半干旱区作物物蒸散量受干旱旱胁迫的显著著影响,以往建建立的湿润区作作物蒸散模型和作作物系数并不适用对其作物物蒸散量的估算算,而目前对这一问题的研研究却十分有限限.利用位于黄土土高原典型半干旱区的"定西西干旱生态环环境综合科学试试验站"春小麦麦农田的蒸渗仪仪、蒸发皿、超声声涡动仪的观测资料及常规规气象观测资料料相结合,分析了该地区实际蒸散量与F AO推荐作物系数数估算的蒸散量之间的差异异性及其随干旱旱胁迫度的变化关系.研究究了该地区春小小麦参考蒸散量与与蒸发皿蒸发量比值和实际际蒸散量与蒸发发皿蒸发量比值随干旱胁迫迫度的变化特征征及春小麦作物系系数对干旱胁迫度的响应规规律,并对FA O推荐值的作作物系数进行了改进.分析发现,由于半干旱旱区作物蒸散受干旱胁迫影影响较大,FAO推荐作物系数数估算的蒸散散量与实际蒸散散量相差很显著著,实实际作物系数对干旱胁迫度度的依赖很强,,随干旱胁迫度增加显著减减少,但其敏感感性在干旱胁迫度度约达到0.7后明显降低.而且,改进的作物系数在作作物生长初期和和发育期远远低低于FAO的推荐荐值和Kumar修正值,改进进的作物系数估估算的春小麦蒸散量也明显显比后两者估算算的更接近实际观观测值,与观测测值线性拟合的系数为0.98,决定系数能能够达到0.455,标准误差也也仅为0.85 mm m,对对半干旱地区春小麦蒸散量量的估算效果比比较理想.
基金This study was funded by Opening Project of State Key Laboratory of Tree Genetics and Breeding,Northeast Forestry University,China(K2020205)National Natural Science Foundation of China(32071521)+1 种基金Key Research and Development Program of Changzhou,China(CJ20200013)Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment.
文摘Drought can affect the growth and soil enzyme activities of invasive alien plants(IAPs).It is imperative to evaluate the competitive advantage of IAPs compared with that of the native species and the activities of soil enzymes under drought.This study aimed to evaluate the competitive advantage of the IAP Amaranthus spinosus that originated from tropical America compared with the native Chinese species A.tricolor and the activities of soil enzymes under drought.A competitive co-culture of A.spinosus and A.tricolor was established using a planting basin experiment.The two species were treated with different levels of drought,i.e.(i)the control;(ii)a light level of drought and(iii)a heavy level of drought.The functional traits,osmotic adjustment and the activities of antioxidant enzymes of the two species,as well as soil pH and electrical conductivity,contents of soil microbial biomass carbon and the activities of soil enzymes were determined.The relative competition intensity and relative dominance of A.spinosus were greater than those of A.tricolor under drought.Drought may provide an advantage to the competitive advantage of A.spinosus.Soil water-soluble salt content and sucrose hydrolytic power of A.spinosus were greater than those of A.tricolor under drought.The ability of A.spinosus to grow in soil with higher levels of water-soluble salt contents and sucrose hydrolytic power under drought may aid in its acquisition and utilization of nutrients.
基金supported by the National Key R&D Program of China(2017YFC0506200).
文摘Aims In estuarine salt-marshes,nitrate supply and soil salinity,which are known as two main environmental drivers,simultaneously affect the interspecific interactions between plant species.However,to date,their interactive effects on interspecific interactions have not been closely examined for salt-marsh plant species.Methods Juvenile plants of Suaeda salsa L.(Chenopodiaceae)and Scirpus planiculmis Fr.(Cyperaceae)were grown in rinsed river sand to conduct a greenhouse experiment with three treatment categories:interspecific interaction(mixed culture or monoculture),three salinity levels(1,50 and 100 mmol L^(-1))and three nitrate levels(0.5,5 and 10 mmol L^(-1)).First,height and biomass of all plants were measured.Then,the growth data,relative interaction index and competitive important index of the two species were analyzed.Important Findings The interspecific interactions between S.salsa and S.planiculmis were facilitation across the salinity gradients.The promotion of S.salsa growth with high nitrate supply did not enhance the facilitative effect of the species,especially at low salinity.However,high nitrate supply significantly shifted the interspecific interactions of S.planiculmis from facilitation to competition at high salinity.Our results suggest that excessive nitrate application changes the prediction of the stress-gradient hypothesis along a salinity gradient,leading to collapse of the two species coexistence in the salt-marshes.These findings make a contribution to the understanding of how S.salsa and S.planiculmis,as well as salt-marsh communities,respond to the human modification of estuarine nutritional levels.
基金supported by the Fundamental Research Funds for the Central Non-Profit Research Institution of Chinese Academy of Forestry(CAFYBB2016SY034,key technologies of functional restoration and directional improvement of mudflat wetland)the National Key R&D Program of China(2017YFC0506200)the Research on the synchronicity of dichogamy in Scirpus planiculmis based on population clonal structure(NSFC31800348).
文摘Heterogeneity of soil salinity is a prominent environmental characteristic in the intertidal zone of estuaries,affecting the plant growth and the shift of biotic interactions in the salt marsh.This study aims to examine the interactive effects of a salinity gradient and salinity fluctuations on intraspecific interactions of a euhalophyte.We assessed the impact of daily fluctuating salinity on the outcome of intraspecific interactions by cultivating seeds of Suaeda salsa(Chenopodiaceae)in river sand.The experiment was conducted in a greenhouse with three treatments:daily salinity fluctuations(static and fluctuating salinity),a salinity gradient(200 and 400 mmol L^(−1))and three planting densities(1,2 and 4 plants/pot).First,height and biomass of plants were measured at both the start and end of the experiment.Then,the growth indexes and log response ratio of S.salsa were analyzed.The outcome of intraspecific interactions of S.salsa shifted from competition in low salinity to facilitation in high salinity,and high conspecific density strengthened the competition and facilitation intensities.Daily salinity fluctuation did not significantly affect the plant growth and the outcome of intraspecific interactions,but did have a significant influence on belowground biomass.Our results suggest that the stress-gradient hypothesis may apply to predicting the variation of the intraspecific relationship of a salt-tolerant species along a salinity gradient,and the magnitude of this variation is density dependent.These findings help us understand how individuals and populations of a euhalophyte species respond to the natural variation or human modification of salinity conditions.
文摘Drought, flood, salinity, or a combination of these limits rice production. Several rice varieties are well known for their tolerance to specific abiotic stresses. We determined genetic relationship among 12 rice varieties including 9 tolerant to drought, flood, or salinity using inter-simple sequence repeat （ISSR） markers. Based on all markers, the nine tolerant varieties formed one cluster distinct from the cluster of three control varieties. The salt-tolerant varieties were closest to two flood-tolerant varieties, and together they were distinct from the drought-tolerant varieties. （GA）8YG was the most informative primer, showing the highest polymorphic information content （PIC） and resolving power （Rp）. The drought-, flood-, and salt-tolerant varieties grouped in three distinct clusters within the group of tolerant varieties, when （GA）8YG was used. Sabita was the only exception. The two aus varieties, Nagina22 and FR13A, were separated and grouped with the drought- and flood-tolerant varieties, respectively, hut they were together in dendrograms based on other primers. The results show that ISSR markers associated with （GA）sYG delineated the three groups of stress-tolerant varieties from each other and can be used to identify genes/new alleles associated with the three abiotic stresses in rice germplasm.
