Effect of nitrogen application on the senescence of flag leaf and yield of rice cultivated in aerobic soil

Effects of nitrogen application models on the leaf senescence and grain yields of rice cultivated in aerobic soil were studied.The total nitrogen fertilizer(600 kg·hm -2)was divided into several applications.The results obtained showed that senescence was effectively delayed and grain numbers per ear and weight per grain and the yield were significantly increased when the basal fertilizer and tillering fertilizer were decreased and earring fertilizer was increased.Compared with the treatment where all the fertilizer was applied as basal fertilizer,the fertilizer applied at the ratios of 3,1,0.75,0.75 and 0.5 of basal fertilizer,tillering fertilizer,spikelet promotion fertilizer,spikelet sustaining fertilizer and grain filling fertilizer,respectively,caused the increased effective leaf index by 8.46% on the earring stage,the increased chlorophyll content of flag leaves by 1.68 mg·g -1 30 d after flowering,the decreased MDA content of flag leaves by 16.2 nmol·g -1 24 d after flowering,the increased one thousand grain weight by 2.3 g and thus the increased grain yield by 14%.