Effects of Irrigation on Starch Content,Related Enzymes and Yield of Jimai 20 Grains

Field experiment was conducted to study the effects of irrigation time and amount on grain starch content,starch synthase activity,grain yield and water use efficiency(WUE) of wheat variety Jimai 20 during 2005~2006.Four water treatments were set up: no irrigation(W0),irrigation at overwintering and jointing stages(W1),irrigation at overwintering,jointing and anthesis stages(W2),irrigation at overwintering,jointing,anthesis and filling stages(W3).Each was irrigated with 60 mm water.The results showed that the amylose content significantly increased with the increase of irrigation amount at the grain-maturing stage,while the amylopectin content was significantly reduced with a reduction in the ratio of amylopectin to amylose.The ratio of amylopectin to amylose of W0 treatment was the highest.The W2 and W3 treatments significantly increased the GBSS activity and reduced the SSS activity at both middle and late grain-filling stages.The highest output values of grain,starch,amylopectin,andamylose were achieved in W1 treatment and more irrigation had no significant influence to them.