干旱胁迫下春小麦需水关键期叶水势的变化及其影响因素研究

Change of leaf water potential and influencing factors of spring wheat during critical water requirement periods under drought stress

为揭示春小麦叶水势对水分胁迫的响应规律,在甘肃省定西干旱气象与生态环境试验站对春小麦在拔节~抽穗期进行水分胁迫试验,研究不同水分胁迫下春小麦叶水势的变化特征及其与环境因子的关系。结果表明:随着水分胁迫程度的增强,春小麦叶水势呈逐渐减小的趋势,且不同水分胁迫下叶水势均表现为拔节期>孕穗期>抽穗期。春小麦叶水势对土壤体积含水率存在阈值反应,当土壤体积含水率>11.5%时,叶水势随土壤体积含水率发生正相关变化;当土壤体积含水率<11.5%则发生负相关变化。在众多环境因子中,大气相对湿度、大气水势与春小麦叶水势呈现出良好的线性关系。通径分析表明,影响轻旱处理下叶水势最强的因子是大气相对湿度,且大气相对湿度为51.87±0.03%时可作为轻旱处理下叶水势发生变化的临界阈值;中旱和重旱处理下影响叶水势的最强因子是大气水势,大气水势为-99.22±8.63 MPa时可作为中旱和重旱处理下叶水势发生变化的临界阈值。该研究为减轻春小麦受旱程度、维持春小麦正常生长及时补充水分提供理论依据。

To study changing characteristics of spring wheat leaf water potential under different water stresses and its relationship with environmental factors,a water stress test was conducted on spring wheat at the jointing-heading stage at the Dingxi Arid Meteorological and Ecological Environment Test Station in Gansu Province.The results showed that with the increase of water stress,the leaf water potential of spring wheat gradually decreased.The leaf water potential under different water stresses was jointing stage>booting stage>heading stage.The leaf water potential of spring wheat had a threshold response to the soil volumetric water content.When the soil volumetric water content was greater than 11.5%,the leaf water potential changed with the soil volumetric water content in a positive correlation,and when the soil volume water content was less than 11.5%,it changed in a negative correlation.Among many environmental factors,two factors of relative atmospheric humidity,atmospheric water potential showed good linear relationship with spring wheat leaf water potential.Path analysis indicated that the strongest factor affecting leaf water potential under mild drought treatment was relative atmospheric humidity.The relative atmospheric humidity of(51.87±0.03)%could be used as the critical threshold for changes in leaf water potential under mild drought treatment.The strongest factor influencing leaf water potential under medium and severe drought treatment was atmospheric water potential.The atmospheric water potential of-99.22±8.63 MPa could be used as the critical threshold for changes in leaf water potential under medium and severe drought treatments.This study has provided a theoretical basis for ensuring timely water supply and reducing drought risk to maintain normal growth of spring wheat.