Changes in nitrogen accumulation,distribution,translocation and nitrogen use efficiency in different wheat cultivars under different irrigation conditions

Differences of nitrogen uptake and utilization in different wheat cultivars under different irrigation amount and at different stages were studied with 15N tracing technique.Three irrigation regimes were applied in the present experiment: no irrigation during the whole growth season(represented as W0);irrigated both before sowing and at jointing stages(W1);irrigated 3 times,before sowing,at jointing and anthesis stages(W2).The results were as follows: under the same irrigation condition,total nitrogen accumulation amount,nitrogen accumulation amount derived from fertilizer and soil of cv.T23 were higher than those of cv.S664.Nitrogen accumulation amount derived from fertilizer and soil in vegetative organs at anthesis,in grain and vegetative organs at maturity of cv.T23,were higher than those of cv.S664.The above results indicated that cv.T23 had higher nitrogen absorptive capacity than cv.S664.Nitrogen translocation amount from fertilizer in vegetative organs after anthesis at treatment W2 was lower than that at treatment W1,while nitrogen translocation amount from soil had no significant change.However,nitrogen translocation amount both from fertilizer and soil were remarkably increased at treatment W2 compared with those at treatment W1.There were no significant difference on grain yield,grain protein yield and nitrogen use efficiency in cv.T23 plants between treatments W1 and W2,but grain protein content,irrigation benefit and water use efficiency at treatment W1 were higher.Grain yield and grain protein yield of cv.S664 at treatment W2 were higher than those at treatment W1,while there were no differences of grain protein content,nitrogen use efficiency,irrigation benefit and water use efficiency between treatments W1 and W2.In conclusion,treatment W1 is better irrigation model for cv.T23 while treatment W2 is better for cv.S664 because of high yield and high water/nitrogen use efficiency.