Effects of nitrogen application rate on flag leaf photosynthetic characteristics and grain growth and development of high-quality wheat

Using pool culture method,the effects of nitrogen rate on photosynthetic rate of flag leaves,kernel growing and developing characteristics as well as yield of two high-quality wheat cultivars were studied.The results indicated that the photosynthetic rate,sucrose content,starch content and kernel weight of strong-gluten wheat 8901 were getting lower with the increasing of N application rate in the range of N 120—360 kg/ha.These indexes of weak gluten wheat SN1391 had a positive correlation with the N application rate in the range of N 120—240 kg/ha,but they decreased sharply when the N application rate increased to 360 kg/ha.In 120—240 kg/ha.Chlorophyll content of both two gluten wheat cultivars went up along with the increasing of N application rate,while it declined if N application rate was excess(240—360 kg/ha).The results also showed that photosynthetic rate was positively correlated with kernel weight,but the correlation between chlorophyll content and photosynthetic rate was not statistically significant.