Photosynthesis and Dry Matter Accumulation of an Early Maturing Rice Line DCG72 under Different Nitrogen Levels

Abstract

     The purpose of this research was to asses photosynthesis and dry matter accumulation of an extremely early maturing rice line DCG72 under different nitrogen levels in spring cropping season 2015 in the green house at VietNam National University of Agriculture. The pot experiment included three nitrogen levels: no nitrogen application (N0; 0 g N/pot), low nitrogn level (N1; 0.5 g N/pot) and high nitrogen level (N2; 1.5 g N/pot). The results showed that the higher nitrogen level was applied, the higher was number of tillers per cluster in early maturing line DCG72 and the check cultivar, KD18. At dough- ripening stage, photosynthetic intensity in DCG72 was significantly higher than in KD18 at N1

but lower at N2 because of low nitrogen content and chlorophyll in leaf in DCG72. The accumulation of dry weight at post-heading stage and the ratio of dry weight of panicle/cluster in DCG72 were significantly lower than those in KD18 at N2. Individual grain yield was similar between two cultivars at N0 but significantly higher in DCG72 than that in KD18 at N1 because of high number of spikelets per panicle and 1,000-grain weight. However, the grain filling ratio (%) in DCG72 was low so that individual grain yield of DCG72 was significantly lower than that of KD18 at N2.