evalution of nitrogen fertilizer effects on paddy yield, yield components and dry matter remobilization of three rice genotype

in order to evaluate the effects of nitrogen fertilizer on yield, yield components and dry matter remobilization of different rice genotypes, a field experiment was carried out at the farm of ramin agricultural and natural resources university (ahwaz/iran) during 2007. experiment was arranged in a split plot based on randomized complete block design with three replications. four nitrogen fertilizer rates (0, 100, 135 and 170 kg.ha-1 from urea source) as the main plots and three rice genotypes (champa, anburi and ld183) as the sub plot were the treatments. results showed that interaction between genotype and nitrogen fertilizer rates had significant effects on paddy yield and dry matter remobilization. ld183 had the highest paddy yield in 170 kgn.ha-1 (6955.81 kg.ha-1). the highest and the lowest amounts of total shoot dry matter remobilization obtained from ld183 in 0 kgn.ha-1 (844.95 kg.ha-1) and anburi in 100 kgn.ha-1 (230.15 kg.ha-1), respectively. results also showed that contribution of stem part in dry matter remobilization was 0.03-12.99% while it was lower than 0.5% and 2% in flag leaf and other leaves, respectively. dry matter remobilization of stem, total shoot and other leaves had a significant and positive correlation with grain yield (r=0.84**, r=0.78** and r=0.5** respectively). it seems that dry matter remobilization have an important role in rice grain filling.