[Objective] In this study,the secretion of organic acids from plant roots under soil nutrient and water stress and the effects of organic acids on ecological adaptability of plants were investigated,which provided the...[Objective] In this study,the secretion of organic acids from plant roots under soil nutrient and water stress and the effects of organic acids on ecological adaptability of plants were investigated,which provided theoretical basis for improving the adaptability of plants to a variety of stress conditions.The results showed that,under nutrient and water stress,the content of organic acids secreted from plant roots increased significantly as a common active adaptive response.Organic acids could improve the activities of a variety of antioxidant enzymes,contents of osmotic regulatory substances,contents of chlorophyll and photosynthesis levels,promote nutrient absorption and transportation in plants,and ultimately contribute to plant growth and biomass accumulation,reduce the toxicity of stress conditions to plants and improve the stress resistance and adaptability of plants.展开更多
[Objective] This study aimed to investigate the effects of nutrient and water stress on the secretion of organic acids from roots of two-year-old Larix olgensis. [Method] Different nutrient and water stress conditions...[Objective] This study aimed to investigate the effects of nutrient and water stress on the secretion of organic acids from roots of two-year-old Larix olgensis. [Method] Different nutrient and water stress conditions were designed to investi- gate the types and quantities of organic acids secreted from roots of two-year-old L. olgensis. [Result] Under nutrient and water stress, the types of organic acids secreted from roots of two-year-old L. olgensis increased, which varied with different stress levels. In addition, nutrient and water stress also increased the secretory vol- ume of organic acids from roots of two-year-old L. olgensis. The increment in total amount of organic acids reached the maximum under Level 1 (high stress). Among different types of organic acids, the increment in secretory volume of citric acid reached the maximum, followed by malic acid, while oxalic acid presented relatively small increment. Furthermore, the increment in secretory volume of these three organic acids all reached the maximum under Level 1. [Conclusion] The proportion of the secretory volume of each organic acid accounting for the total amount of organic acids varied slightly, but the overall order was unchanged.展开更多
The effects of NaCl salinity and NO^-3 on growth, root morphology, and nitrogen uptake of a halophyte Suaeda physophora were evaluated in a factorial experiment with four concentrations of NaCl (1, 150, 300, and 450 ...The effects of NaCl salinity and NO^-3 on growth, root morphology, and nitrogen uptake of a halophyte Suaeda physophora were evaluated in a factorial experiment with four concentrations of NaCl (1, 150, 300, and 450 mmol L^-1) and three NO^-3 levels (0.05, 5, and 10 mmol L^-1) in solution culture for 30 d. Addition of NO^-3 at 10 mmol L^-1 significantly improved the shoot (P 〈 0.001) and root (P 〈 0.001) growth and the promotive effect of NO^-3 was more pronounced on root dry weight despite the high NaCl concentration in the culture solution, leading to a significant increase in the root:shoot ratio (P 〈 0.01). Lateral root length, but not primary root length, considerably increased with increasing NaCl salinity and NO^-3 levels (P 〈 0.001), implying that Na^+ and NO3^- in the culture solution simultaneously stimulated lateral root growth. Concentrations of Na^+ in plant tissues were also significantly increased by higher NaCl treatments (P 〈 0.001). At 10 mmol L^-1 NO^-3, the concentrations of NO^-3 and total nitrogen and nitrate reductase activities in the roots were remarkably reduced by increasing salinity (P 〈 0.001), but were unaffected in the shoots. The results indicated that the fine lateral root development and effective nitrogen uptake of the shoots might contribute to high salt tolerance of S. physophora under adequate NO^-3 supply.展开更多
[Objective] This study aimed to further explore the dynamics of related physiological indexes of rice seedlings under different NH4+ /NO3- ratio and different water condition. [Method] Under the hydroponic condition ...[Objective] This study aimed to further explore the dynamics of related physiological indexes of rice seedlings under different NH4+ /NO3- ratio and different water condition. [Method] Under the hydroponic condition in laboratory, 3 NH4+/NO3- ratios (0/100, 50/50 and 100/0) and 2 water conditions (+PEG,-PEG) were designed for Fengliangyou 7203. [Result] The root-canopy ratio of rice seedlings increased under any of the NH4+/NO3- ratios and water conditions. Under water stress, the root-canopy ratio of rice seedlings changed most greatly at the NH4+/NO3- ratio of 0/ 100; the overall water potential of rice seedlings reached the lowest at the NH4+/ NO3- ratio of 100/0; and the changes of water potential and xylem flow pH were relatively stable at the NH4+/NO3- ratio of 50/50. Under the condition of no water stress, the growth of rice seedlings was best at the NH4+/NO3- ratio of 50/50, followed by the NH4+/NO3- ratios of 0/100 and 100/0. [Conclusion] This study will pro- vide a basis for understanding the relationship between water potential and xylem flow.展开更多
[Objective] This study to aimed to investigate the effects of Cu stress on root exudates and microbial activities in rhizosphere of grafted and ungrafted cucum-ber seedlings, and therefore to elucidate the microbial m...[Objective] This study to aimed to investigate the effects of Cu stress on root exudates and microbial activities in rhizosphere of grafted and ungrafted cucum-ber seedlings, and therefore to elucidate the microbial mechanism of grafting for in-creasing cucumber plants tolerance to Cu stress [Method] Four treatments: (1) un-grafted seedlings + test soil (U0); (2) ungrafted seedlings + test soil + CuSO4·5H2O (U1); (3) grafted seedlings + test soil (G0); (4) grafted seedlings + test soil + Cu-SO4·5H2O (G1) were set in the pot culture experiment. The contents of free amino acids, organic acids, phenolic acid and sugars, microbial population and enzyme ac-tivity in the four treatment were measured, respectively. [Result] The secretion of amino acids and organic acids were increased under Cu stress. The amino acids secretions of grafted seedlings roots were obviously higher than ungrafted seedlings except for Phe and Val. At the same time, the secretion of oxalic acid, malic acid, acetic acid, citric acid, cinnamic acid, ρ-hydroxybenzoic acid and benzoic acid of grafted seedlings were significantly higher than ungrafted seedlings as wel . There-fore, more Cu2+ were restricted in soil by chelating, complexing and precipitation with root exudates, and its toxicity was decreased. The soil microbial biomass C and N in grafted cucumber rhizosphere were significantly higher than those in ungrafted cu-cumber rhizosphere, whereas basal respiration and metabolic quotient were signifi-cantly lower. Under Cu stress, the numbers of actinomyces and nitrogen fixing bac-teria decreased and the number of fungi increased significantly, whereas there was no significant difference in amounts of bacteria. The numbers of bacteria, actino-myces, and nitrogen fixing bacteria in grafted cucumber rhizosphere were significant-ly higher than those in ungrafted cucumber rhizosphere, but the number of fungi was opposite. The activities of soil urease, phosphatase, sucrase and catalase in grafted cucumber rhizosphere were significantly higher than those in ungrafted cu-cumber rhizosphere. [Conclusion] These indicated that the soil microbial environment and soil enzymes activities were improved by grafting under Cu stress, and as a re-sult, the adaptability of cucumber to Cu stress was improved.展开更多
Aims Drought and salinity are severe abiotic stress factors,which limit plant growth and productivity,particularly in desert regions.In this study,we employed two desert poplars,Populus euphratica Oliver and Populus p...Aims Drought and salinity are severe abiotic stress factors,which limit plant growth and productivity,particularly in desert regions.In this study,we employed two desert poplars,Populus euphratica Oliver and Populus pruinosa Schrenk seedlings,to compare their tolerance to drought,salinity and combined stress.Methods We investigated species-specific responses of P.euphratica and P.pruinosa in growth,photosynthetic capacity and pigment contents,nonstructural carbohydrate concentrations,Cl−allocation,osmotic regulation and the accumulation of reactive oxygen species(ROS)under drought,salinity and the combined stress.Important Findings Populus pruinosa exhibited greater growth inhibitory effects,photosynthesis decline,stomatal closure and ROS accumulation,and lower antioxidant enzyme activities and osmotic regulation compared with P.euphratica under drought,salinity and especially under their combined stress.On the other hand,salt-stressed P.euphratica plants restricted salt transportation from roots to leaves,and allocated more Cl−to coarse roots and less to leaves,whereas salt-stressed P.pruinosa allocated more Cl−to leaves.It was shown that there is species-specific variation in these two desert poplars,and P.pruinosa suffers greater negative effects compared with P.euphratica under drought,salinity and especially under the combined stress.Therefore,in ecological restoration and afforestation efforts,species-specific responses and tolerances of these two poplar species to drought and salinity should be considered under climate change with increasing drought and soil salinity developing.展开更多
Aims Predicting drought consequences on forests and fruit crop plantings requires improved understanding of drought responses of both leaf and fine-root resource acquisitive traits(specific leaf area—SLA,specific roo...Aims Predicting drought consequences on forests and fruit crop plantings requires improved understanding of drought responses of both leaf and fine-root resource acquisitive traits(specific leaf area—SLA,specific root surface area—SRA and specific root length—SRL).We hypothesize their responses are coordinated towards integrated plant resource conservation under severe drought.Methods We tested the hypothesis with a greenhouse-based drought experiment on saplings of six Prunus hybrids with a priori known contrasting drought sensitivity.Saplings were subjected to either control(100%field capacity)or severe drought stress treatment(33%evapotranspiration of hybrid-specific control plants).Sample collections were carried out at 30 and at 60 days after the start of treatments,for both control and stressed saplings.Important Findings No hybrid showed concurrent significant decrease of SLA and SRA(or SRL)under severe drought.The fine-root traits of the six hybrids showed two major drought-response scenarios,in particular:(i)increased root tissue density(RTD)and decreased average root diameter without significant change of SRL and(ii)increased RTD and decreased SRL without significant change of average root diameter.Drought responses of leaf gas exchange,SRA,SRL and RTD were closely correlated along a gradient towards resource conservation from control to drought-stressed plants in all hybrids,which was orthogonal to another gradient characterized by a hybrid-dependent decrease of SLA.These findings highlight(i)the multi-dimensionality of root-trait drought responses,(ii)the decoupling between leaf economics and leaf hydraulics and(iii)the covariation of leaf and root hydraulics in terms of trait drought responses.The study contributes to identifying the origin of the multi-dimensionality of root-trait drought response at intraspecific scale,and highlights differential drought–response combinations of leaf and fine-root traits among hybrids to survive under severe soil drought stress.展开更多
基金Supported by National Natural Science Foundation of China(31370613)Major State Basic Research Development Program of China(973 Program)(2011CB403202)Fundamental Research Funds for the Central Universities(DL12CA01)~~
文摘[Objective] In this study,the secretion of organic acids from plant roots under soil nutrient and water stress and the effects of organic acids on ecological adaptability of plants were investigated,which provided theoretical basis for improving the adaptability of plants to a variety of stress conditions.The results showed that,under nutrient and water stress,the content of organic acids secreted from plant roots increased significantly as a common active adaptive response.Organic acids could improve the activities of a variety of antioxidant enzymes,contents of osmotic regulatory substances,contents of chlorophyll and photosynthesis levels,promote nutrient absorption and transportation in plants,and ultimately contribute to plant growth and biomass accumulation,reduce the toxicity of stress conditions to plants and improve the stress resistance and adaptability of plants.
基金Supported by National Natural Science Foundation of China(31370613)Major State Basic Research Development Program of China(973 Program)(2011CB403202)+1 种基金Project of General Administration of Quality Supervision,Inspection and Quarantine of China(2009IK177)Fundamental Research Fund for the Central Universities(DL12CA01)~~
文摘[Objective] This study aimed to investigate the effects of nutrient and water stress on the secretion of organic acids from roots of two-year-old Larix olgensis. [Method] Different nutrient and water stress conditions were designed to investi- gate the types and quantities of organic acids secreted from roots of two-year-old L. olgensis. [Result] Under nutrient and water stress, the types of organic acids secreted from roots of two-year-old L. olgensis increased, which varied with different stress levels. In addition, nutrient and water stress also increased the secretory vol- ume of organic acids from roots of two-year-old L. olgensis. The increment in total amount of organic acids reached the maximum under Level 1 (high stress). Among different types of organic acids, the increment in secretory volume of citric acid reached the maximum, followed by malic acid, while oxalic acid presented relatively small increment. Furthermore, the increment in secretory volume of these three organic acids all reached the maximum under Level 1. [Conclusion] The proportion of the secretory volume of each organic acid accounting for the total amount of organic acids varied slightly, but the overall order was unchanged.
基金Supported by the Key Technology Program of the Xinjiang Uygur Autonomous Region, China (No.200733144-1)the Knowledge Innovation Project of the Chinese of Academy of Sciences (No.KSCX2-YW-N-41)
文摘The effects of NaCl salinity and NO^-3 on growth, root morphology, and nitrogen uptake of a halophyte Suaeda physophora were evaluated in a factorial experiment with four concentrations of NaCl (1, 150, 300, and 450 mmol L^-1) and three NO^-3 levels (0.05, 5, and 10 mmol L^-1) in solution culture for 30 d. Addition of NO^-3 at 10 mmol L^-1 significantly improved the shoot (P 〈 0.001) and root (P 〈 0.001) growth and the promotive effect of NO^-3 was more pronounced on root dry weight despite the high NaCl concentration in the culture solution, leading to a significant increase in the root:shoot ratio (P 〈 0.01). Lateral root length, but not primary root length, considerably increased with increasing NaCl salinity and NO^-3 levels (P 〈 0.001), implying that Na^+ and NO3^- in the culture solution simultaneously stimulated lateral root growth. Concentrations of Na^+ in plant tissues were also significantly increased by higher NaCl treatments (P 〈 0.001). At 10 mmol L^-1 NO^-3, the concentrations of NO^-3 and total nitrogen and nitrate reductase activities in the roots were remarkably reduced by increasing salinity (P 〈 0.001), but were unaffected in the shoots. The results indicated that the fine lateral root development and effective nitrogen uptake of the shoots might contribute to high salt tolerance of S. physophora under adequate NO^-3 supply.
基金Supported by Natural Science Foundation of Guangdong Province(2014 A030307013)~~
文摘[Objective] This study aimed to further explore the dynamics of related physiological indexes of rice seedlings under different NH4+ /NO3- ratio and different water condition. [Method] Under the hydroponic condition in laboratory, 3 NH4+/NO3- ratios (0/100, 50/50 and 100/0) and 2 water conditions (+PEG,-PEG) were designed for Fengliangyou 7203. [Result] The root-canopy ratio of rice seedlings increased under any of the NH4+/NO3- ratios and water conditions. Under water stress, the root-canopy ratio of rice seedlings changed most greatly at the NH4+/NO3- ratio of 0/ 100; the overall water potential of rice seedlings reached the lowest at the NH4+/ NO3- ratio of 100/0; and the changes of water potential and xylem flow pH were relatively stable at the NH4+/NO3- ratio of 50/50. Under the condition of no water stress, the growth of rice seedlings was best at the NH4+/NO3- ratio of 50/50, followed by the NH4+/NO3- ratios of 0/100 and 100/0. [Conclusion] This study will pro- vide a basis for understanding the relationship between water potential and xylem flow.
基金Supported by Shandong Modern Agricultural Technology & Industry System
文摘[Objective] This study to aimed to investigate the effects of Cu stress on root exudates and microbial activities in rhizosphere of grafted and ungrafted cucum-ber seedlings, and therefore to elucidate the microbial mechanism of grafting for in-creasing cucumber plants tolerance to Cu stress [Method] Four treatments: (1) un-grafted seedlings + test soil (U0); (2) ungrafted seedlings + test soil + CuSO4·5H2O (U1); (3) grafted seedlings + test soil (G0); (4) grafted seedlings + test soil + Cu-SO4·5H2O (G1) were set in the pot culture experiment. The contents of free amino acids, organic acids, phenolic acid and sugars, microbial population and enzyme ac-tivity in the four treatment were measured, respectively. [Result] The secretion of amino acids and organic acids were increased under Cu stress. The amino acids secretions of grafted seedlings roots were obviously higher than ungrafted seedlings except for Phe and Val. At the same time, the secretion of oxalic acid, malic acid, acetic acid, citric acid, cinnamic acid, ρ-hydroxybenzoic acid and benzoic acid of grafted seedlings were significantly higher than ungrafted seedlings as wel . There-fore, more Cu2+ were restricted in soil by chelating, complexing and precipitation with root exudates, and its toxicity was decreased. The soil microbial biomass C and N in grafted cucumber rhizosphere were significantly higher than those in ungrafted cu-cumber rhizosphere, whereas basal respiration and metabolic quotient were signifi-cantly lower. Under Cu stress, the numbers of actinomyces and nitrogen fixing bac-teria decreased and the number of fungi increased significantly, whereas there was no significant difference in amounts of bacteria. The numbers of bacteria, actino-myces, and nitrogen fixing bacteria in grafted cucumber rhizosphere were significant-ly higher than those in ungrafted cucumber rhizosphere, but the number of fungi was opposite. The activities of soil urease, phosphatase, sucrase and catalase in grafted cucumber rhizosphere were significantly higher than those in ungrafted cu-cumber rhizosphere. [Conclusion] These indicated that the soil microbial environment and soil enzymes activities were improved by grafting under Cu stress, and as a re-sult, the adaptability of cucumber to Cu stress was improved.
基金supported by the Natural Science Foundation of China(U1803231)and the Talent Program of the Hangzhou Normal University(2016QDL020).
文摘Aims Drought and salinity are severe abiotic stress factors,which limit plant growth and productivity,particularly in desert regions.In this study,we employed two desert poplars,Populus euphratica Oliver and Populus pruinosa Schrenk seedlings,to compare their tolerance to drought,salinity and combined stress.Methods We investigated species-specific responses of P.euphratica and P.pruinosa in growth,photosynthetic capacity and pigment contents,nonstructural carbohydrate concentrations,Cl−allocation,osmotic regulation and the accumulation of reactive oxygen species(ROS)under drought,salinity and the combined stress.Important Findings Populus pruinosa exhibited greater growth inhibitory effects,photosynthesis decline,stomatal closure and ROS accumulation,and lower antioxidant enzyme activities and osmotic regulation compared with P.euphratica under drought,salinity and especially under their combined stress.On the other hand,salt-stressed P.euphratica plants restricted salt transportation from roots to leaves,and allocated more Cl−to coarse roots and less to leaves,whereas salt-stressed P.pruinosa allocated more Cl−to leaves.It was shown that there is species-specific variation in these two desert poplars,and P.pruinosa suffers greater negative effects compared with P.euphratica under drought,salinity and especially under the combined stress.Therefore,in ecological restoration and afforestation efforts,species-specific responses and tolerances of these two poplar species to drought and salinity should be considered under climate change with increasing drought and soil salinity developing.
基金supported by the Australian almond industry through Horticulture Innovation Australia Limited(Hort Innovation)using the almond industry research and development levy and funds from the Australian Government(AL13009)In-kind funding support from The Commonwealth Scientific and Industrial Research Organisation(CSIRO)is also gratefully acknowledged.
文摘Aims Predicting drought consequences on forests and fruit crop plantings requires improved understanding of drought responses of both leaf and fine-root resource acquisitive traits(specific leaf area—SLA,specific root surface area—SRA and specific root length—SRL).We hypothesize their responses are coordinated towards integrated plant resource conservation under severe drought.Methods We tested the hypothesis with a greenhouse-based drought experiment on saplings of six Prunus hybrids with a priori known contrasting drought sensitivity.Saplings were subjected to either control(100%field capacity)or severe drought stress treatment(33%evapotranspiration of hybrid-specific control plants).Sample collections were carried out at 30 and at 60 days after the start of treatments,for both control and stressed saplings.Important Findings No hybrid showed concurrent significant decrease of SLA and SRA(or SRL)under severe drought.The fine-root traits of the six hybrids showed two major drought-response scenarios,in particular:(i)increased root tissue density(RTD)and decreased average root diameter without significant change of SRL and(ii)increased RTD and decreased SRL without significant change of average root diameter.Drought responses of leaf gas exchange,SRA,SRL and RTD were closely correlated along a gradient towards resource conservation from control to drought-stressed plants in all hybrids,which was orthogonal to another gradient characterized by a hybrid-dependent decrease of SLA.These findings highlight(i)the multi-dimensionality of root-trait drought responses,(ii)the decoupling between leaf economics and leaf hydraulics and(iii)the covariation of leaf and root hydraulics in terms of trait drought responses.The study contributes to identifying the origin of the multi-dimensionality of root-trait drought response at intraspecific scale,and highlights differential drought–response combinations of leaf and fine-root traits among hybrids to survive under severe soil drought stress.