Accumulation and translocation of dry matter and N 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 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 yield are more than 10.50 t/hm2 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.