水分胁迫持续时间对冬小麦根冠生物量累积的影响

为了解冬小麦根、冠对土壤含水量变化的响应,对不同水分条件下温室盆栽冬小麦作了分析研究。该试验包括七个水分状态,充分供水A处理(75%~100?,FC为田间持水量),中度胁迫B处理(55%~65?)和重度胁迫C处理(35%~45?)以及分蘖期开始中度、重度胁迫到孕穗期复水的BA1、CA1处理和抽穗期复水的BA2、CA2处理。试验结果表明:分蘖期开始的水分胁迫无论何时恢复供水都不影响冬小麦根、冠生长过程的总趋势;但随胁迫程度、胁迫持续时间的增加,胁迫期内根、冠的相对生长率,根、冠总重均降低,但根重占有量增大,且水分供应量的减少和胁迫时间的延长使冬小麦生育周期提前结束;随胁迫的增加,胁迫时间的延续,最大根重减小,但较大根重维持的时间延长;当复水后,各处理对复水存在不同程度的滞后效应和激发补偿生长,导致短期胁迫的根重占有量小于长期胁迫处理,中度胁迫小于重度胁迫,冠重也随之改变。造成此现象的原因:水分胁迫影响植株的功能,但自适应能力的作用促使分配于根系的同化物质增加,改善和提高根系的吸水能力,缓减植株由于缺水造成损失;对于供水超过75?的植株,生育后期的冠重占有量较小,根重较大则归因于生长过程已形成的庞大根系。

The effect of sustaining time of watering stress on root and shoot weight accumulation in winter wheat

In order to study the response of root and shoot of winter wheat to changeable water in different growth stages,the experiment was conducted by pot cultivation under greenhouse, with well-watered treatment,mild and severe stress treatment in full growth stage,and mild and severe stress treatment from tilling stage to spiking stage or tassel stage,respectively.The results showed that root and shoot of winter wheat had different response to changeable water.The relative growth rate of root to shoot was decreased under different degree and time of stress;the proportion of root weight to total weight was increased,while that of shoot weight was decreased.With stress extending,the growth period of winter wheat was shorten;under severe stress or extending mild stress,the maximum of root was reduced,but its sustaining time was prolonged.After rewatering,in spite of increasing growth of root and shoot,the proportion of root weight under mild stress was less than that under severe stress,and the proportion of root weight under short-time stress was less than that under long-time stress.The phenomena could be regarded as lag-time effect.The effect of root and shoot to water indicates that winter wheat adopt to surrounding stress through self-adjustment,namely,by increasing root weight or decreasing root loss,and improving water-absorbing function to finish shoot growth in reproductive stage.