水分胁迫后复水对冬小麦叶面积的激发作用

 在不同生育时期遭受不同程度及不同持续时间水分胁迫的冬小麦复水后 ,对叶面积存在明显的激发作用。结果表明 ,复水对叶面积的激发幅度与复水前胁迫发生时期、胁迫程度及其持续时间有关。早期胁迫比中期胁迫复水对叶面积的激发幅度大 ;复水对叶面积的激发幅度与胁迫前的胁迫程度呈正相关 ,而与胁迫持续时间呈负相关 ,即胁迫程度越高 ,胁迫持续时间越短 ,激发幅度越大。但从叶面积最终可恢复到的程度看 ,与胁迫程度及持续时间都呈负相关。不论胁迫发生在哪个时期 ,复水对冬小麦叶面积的激发 ,都是通过增加新生蘖叶面积实现的 ,复水对主茎叶片数及叶片尺寸影响不大。激发作用对最终籽粒产量的贡献 ,中度胁迫下可达到 4 5 % ,重度胁迫下则可高达 6 7%。尽管复水的激发作用能挽回胁迫期间的部分损失 ,但小麦最终叶面积及产量均不能恢复到适宜供水的对照水平

The Stimulating Effects of Rewatering in Subjecting to Water Stress on Leaf Area of Winter Wheat

After subjecting to water stress at different growth stages,by various level and duration, rewatering could stimulate the leaf area of winter wheat greatly. The results showed that the stimulation was affected by the period at which stress occurred, the stress level and its duration. The stimulation of the earlier stress followed by rewatering is greater than that of later stress. Severe water stress promoted the stimulation more than the moderate stress, while longer duration of stress decreased it. However, the final leaf area under severe stress or under longer duration recovered to a less degree than that under moderate stress or under shorter duration. No matter in which growth stage the stress occured, the stimulating mechanism is the same: the increase of total leaf area results from the increase of the leaf area of the tillers. Once the leaf on the main stem emerged during stress period, rewatering had no effect on its size, and consequently its leaf area. The stimulation of rewatering on leaf area contributed 45% to the final grain yield under moderate stress, and as high as 67% under severs stress. Although the stimulation partly compensated for the loss during stress, the final leaf area attained and the corresponding grain yield could not recover to the control level.