外源钙对干旱胁迫下岩溶山区白刺花幼苗生长、生理特性的影响

为揭示岩溶山区白刺花耐旱性与外源钙的关系及抗旱机理,以贵州野生白刺花为试验材料,利用聚乙二醇(PEG)溶液模拟干旱,以未加PEG的1/2浓度Hoagland营养液为对照,研究了外源钙对PEG诱导的干旱胁迫下白刺花幼苗生长和生理的影响,并利用隶属函数综合评价出最佳的外源钙施用量。结果表明,未施入外源钙时,随着PEG诱导的干旱胁迫强度的增加,白刺花幼苗根干重、根冠比、丙二醛(MDA)含量、过氧化氢酶(CAT)活性均逐渐增加,当胁迫浓度为10%时,以上指标均显著高于对照;可溶性蛋白、超氧化物歧化酶(SOD)、过氧化物酶(POD)呈先升高后降低趋势,均(除POD外)在胁迫浓度为10%时达到最大值,与对照相比差异显著;白刺花幼苗地上部生物量、净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)均呈降低趋势,其中地上部生物量、Pn在胁迫浓度为10%时显著降低,Gs和Tr在胁迫浓度为15%时显著降低。在PEG诱导的干旱胁迫下,白刺花幼苗通过提高渗透调节物质含量、增强保护酶活性、增加根冠比等来适应干旱环境。施入适宜浓度的外源钙,显著抑制了PEG诱导的干旱胁迫下白刺花幼苗地上部生物量、Pn、Gs和Tr降低的幅度以及MDA含量增加的幅度;显著促进了根干重、可溶性蛋白含量及SOD、POD和CAT活性的增加,即PEG诱导的干旱胁迫下外源钙可以进一步提高白刺花幼苗根干重和幼苗中渗透调节物质含量,增强保护酶活性,降低Tr,维持生长、生理和光合功能,增强白刺花的抗旱能力。隶属函数综合评价指出,本试验条件下施入50 mmol·L~(-1)的外源钙对提高白刺花幼苗抗旱性的效果最佳。本研究结果为更加充分、合理地利用白刺花灌丛资源提供了理论依据。

Effects of Exogenous Ca2+ on the Growth,Physiological Characters of Sophora viciifolia Seedlings in Karst Mountain Area Under the Drought Stress

In order to study the interaction of drought tolerance of Sophora viciifolia in Karst Mountain Area and exogenous calcium,and the drought-resistance mechanism,the seedlings of Sophora viciifolia were used in this study.PEG were induced to simulate the drought condition.One half concentration of hoagland nutrient solution without PEG was defined as control.The effect of calcium on the growth,physiological responses under drought stress induced by PEG were studied.The results showed that with the increase of drought stress induced by PEG,the root dry weight,root -shoot ratio,the content of MDA and the activities of CAT in Sophora viciifolia leaves increased gradually,which significantly higher than the control when the stress intensity of PEG was 10％.The content of soluble protein,the activities of SOD and POD in Sophora viciifolia leaves increased firstly and then decreased,which (except for POD) were significantly higher than the control and reached the maximum value when exposed to 10％ of PEG.The aboveground biomass,net photosynthetic rate (Pn),stomatal conductance (Gs) and transpiration rate (Tr) in Sophora viciifolia leaves decreased.The above-ground biomass and Pn decreased significantly when the stress intensity of PEG was 10％.Gs and Tr decreased significantly when the stress intensity of PEG was 15％.The seedling of Sophora viciifolia took the strategy that increase the content of osmotic adjustment matter,the activities of protective enzyme,and the root-shoot ratio to adapt to the drought environment induced by PEG-6000.Under drought stress induced by PEG with the addition of Ca2 +,the above-ground biomass,the scale of decrease of net photosynthetic rate (Pn),stomatal conductance(Gs),transpiration rate(Tr) and the degree of increase of the content of MDA were significantly reduced.The root dry weight,the increasing extent of soluble protein content,activities of SOD,POD and CAT were significantly increased.Therefore,Sophora viciifolia seedling increased the root dry weight,the content of osmotic adjustment matter and the activities of protective enzymes,decreased the transpiration rate,and protected the photosynthetic system under the drought stress induced by PEG with the addition of Ca2+.According to the results of subordinate function value analysis,50 mmol· L-1 exogenous calcium application is the best choice to alleviate the impact of drought stress on Sophora viciifolia.The results provide the theory evidence for adequately and reasonably using the Sophora viciifolia.