Effect of Regulated Deficit Irrigation on Photosynthesis Rate at Different Growth Stages of Winter Wheat

Under conditions of rain-proof shelter and cultivated in pots with winter wheat(Triticum aestivum L.),the experiment for Regulated Deficit Irrigation(RDI) was conducted to investigate the effects of RDI on photosynthesis rate at different growth stages of winter wheat,to seek for the suitable stages of RDI and degree of water deficit,and to offer technique parameters for the establishment of RDI indices and model in winter wheat.A two-factor(growing stages and degrees of water deficit) randomized block design was employed in pot culture.The results showed that there was no significant effect of water deficit from green-returning to jointing stages on photosynthesis rate in winter wheat;photosynthesis rate was not restrained obviously in light water deficit period from jointing to heading stages,and there was a super-compensation effect on photosynthesis rate after re-watering,but photosynthesis rate was restrained obviously in medium or severe water deficit period,although there was a compensation after re-watering,there was no obvious difference between photosynthesis rate in water deficit treatments and that in CK;while there was no significant effect of light water deficit on photosynthesis rate from heading to filling stages,but photosynthesis rate was restrained severely in medium or severe water deficit period,and there was only a weaker-compensation effect in photosynthesis rate after re-watering.Therefore,it could be suggested that the suitable growth stages to impose RDI in winter wheat was before jointing stage,and the suitable degree of water deficit was 50% ～65% FC;and light water deficit could be applied at both from jointing to heading stages and from heading to filling stages,the suitable degree of water deficit was 60% ～65% FC.