Differences between soybean genotypes in physiological response to sequential soil drying and rewetting

作     者：Md Mokter Hossain Xueyi Liu Xusheng Qi Hon-Ming Lam Jianhua Zhang 

作者机构：School of Life Sciences and Center for Soybean Research of the State Key Laboratory of Agrobiotechnology The Chinese University of Hong KongShatin Institute of Economic Crops Shanxi Academy of Agricultural Sciences Institute of Crop Science Gansu Academy of Agricultural Sciences 

出 版 物：《The Crop Journal》 (作物学报（英文版）)

年 卷 期：2014年第2卷第6期

页      面：366-380页

学科分类：0710[理学-生物学] 09[农学] 0901[农学-作物学] 0902[农学-园艺学] 

基　　金：supported by the Hong Kong RGC Collaborative Research Fund (CUHK3/CRF/ 11G) to Prof. H.-M. Lam. and J.H. Zhang 

主　　题：Drought tolerance Water restriction Photosynthesis Root growth Xylem sap pH Soybean genotypes 

摘      要：Soybean genotypes show diverse physiological responses to drought, but specific physiological traits that can be used to evaluate drought tolerance have not been identified. In the present study we investigated physiological traits of soybean genotypes under progressive soil drying and rewetting, using a treatment mimicking field *** a preliminary study with eight soybean genotypes, two drought-tolerant genotypes and one susceptible genotype were grown in the greenhouse and subjected to water restriction. Leaf expansion rate, gas exchange, water relation parameters, total chlorophyll(Chl), proline contents of leaves, and root xylem p H were monitored in a time course, and plant growth and root traits were measured at the end of the stress cycle. Drought-tolerant genotypes maintained higher leaf expansion rate, net photosynthetic rate(Pn), Chl content,instantaneous water use efficiency(WUEi), % relative water content(RWC), water potential(ψw), and turgor potential(ψp) during progressive soil drying and subsequent rewetting than the susceptible genotypes. By contrast, stomatal conductance(gs) and transpiration rate(Tr)of tolerant genotypes declined faster owing to dehydration and recovered more sharply after rehydration than the same parameters in susceptible ones. Water stress caused a significant increase in leaf proline level and root xylem sap p H of both genotypes but tolerant genotypes recovered to pre-stress levels more quickly after rehydration. Tolerant genotypes also produced longer roots with higher dry mass than susceptible genotypes. We conclude that rapid perception and adjustment in response to soil drying and rewetting as well as the maintenance of relatively high Pn, %RWC, and root growth constitute the mechanisms by which drought-tolerant soybean genotypes cope with water stress.