Accumulation and translocation of dry matter and nitrogen nutrition in organs of rice cultivars with different productivity levels

A field experiment was carried out to investigate the productivity of rice under the nitrogen(N) fertilization.There were 50 early-maturing late Japonica rice cultivars which are adopted in the region of Yangtze River,and seven nitrogen levels,0,150.0,187.5,225.0,262.5,300.0,and 337.5 kg/ha.The highest productivity of rice cultivar under the seven nitrogen levels was defined as the highest population productivity of N fertilization(HPPN).Then according to HPPN,rice cultivars are classified into four types,top type,high type,middle type and low type.On this basis,the accumulation and translocation of dry matter and N of the four types of rice cultivars were studied.The main results show that the N concentrations and accumulation of leaves are decreased as the decrease of the productivity level at the heading.Also the dry matter and N accumulations of leaves and panicles at the maturity are decreased as the decrease of the productivity level at the maturity.From elongation to heading,the rate of dry matter and N accumulation of stems-sheaths/leaves are decreased as the decrease of the productivity level at the maturity.From the heading to maturity,the dry matter/N TCRV(translocation conversation rate of vegetative organ) of stems-sheaths/leaves of the top level are smaller than those of the other three levels,while the increase of dry matter/N accumulation in panicle are bigger.There are significant positive correlations between dry matter/N accumulation rate and HPPN from the elongation to heading(r=0.635,r=0.539).From the heading to maturity,there is a significant negative correlation between dry matter translocation of leaves and HPPN(r=-0.360),while there is a significant positive correlation between N accumulation of leaf and HPPN(r=0.333).The rice cultivars which yields are more than 10.50 t/ha have obvious advantages than other cultivars in nutrition of dry matter and N of leaves after the heading of rice.Therefore,appropriate dry matter and N accumulation of stems-sheaths,better dry matter and N accumulation of leaves,and bigger dry matter and N accumulation of panicles are benefit for grain yield increasing.