喷灌条件下不同灌水处理冬小麦的叶水势特征

在喷灌区一季冬小麦的试验表明,冬小麦叶水势值在各生育期每天的1400左右发生明显变化;从生育期看,返青期叶水势低谷值出现较晚,持续时间短且恢复较快;孕穗和开花期低谷出现有提前和持续时间延长趋势;叶水势不完全随生育进程与土壤水分同步变化,原因为同一时期内土壤水分是造成叶水势差异的主导因素,但同时外界条件的变化也对叶水势的变化有一定的影响作用。前期叶水势在黎明前和中午都与浅层土壤水分关系密切;到开花和灌浆期叶水势则变为只在中午与浅层土壤水分关系密切,黎明前更多依赖深层土壤水分状况,表现为与深层土壤水分关系密切。喷灌条件下,当返青后灌水量超过150mm时,灌水量对叶水势的影响减小。

CHARACTERISTICS OF LEAF WATER POTENTIAL OF WINTER WHEAT WITH DIFFERENT WATER TREATMENTS UNDER SPRINKLING IRRIGATION

It was shown by the experiment carried out in the sprinkling irrigation area that change in leaf water potential was obvious at 14:00 everyday; at the regreening stage the lowest leaf water potential appeared later and lasted a short time and recovered rapidly, while at the booting and blooming stages it showed up earlier and lasted longer; The change in leaf water potential was not completely in consistence with the change in soil water content during the growing stage, because besides soil water content, surrounding conditions also have influence on leaf water potential. A close relationship could be observed between pre-dawn and mid-day leaf water potentials and water content of soil surface at the early growth stage. With the plants grew up, the correlation of leaf water potential with soil water content in deeper soil layers was getting significant. Under sprinkling irrigation, when the irrigation rate exceeded 150mm after the wheat returned green, its effect on leaf water potential decreased.