Study the effect of nitrogen fertilizer management on dry matter remobilization of three cultivars of rice (Oryza sativa L.).

In order to study the effect of nitrogen fertilizer management on dry matter remobilization among three rice cultivars, a field experiment was carried out at the Rice Research Institute of Iran-Deputy of Mazandaran (Amol). In 2005, a split-split experiment in the basis of randomized complete block design with 3 replications and 3 factors were used in which fertilizer rate (100, 150 and 200 kg ha(-1) from urea source), fertilizer split application (3 levels in variable ratios in transplanting, tillering and heading stages and cultivars (Tarom, Shafagh and Bahar1) were the treatments. Results showed that nitrogen fertilizer rates and split application had significant effect on dry matter remobilization amount in total shoot, stem and leaves (except flag leaf) in which among cultivars, Shafagh had the highest amount in terms of stem and total shoot dry matter remobilization. This amount was obtained at the 100 kg ha(-1) nitrogen fertilizer and the first split application treatment. The highest rate of dry matter remobilization in leaves (except flag leaf) related to Bahar1 that obtained in 200 kg ha(-1) nitrogen fertilizer level. Also, flag leaf of Bahar1 had the highest dry matter remobilization amount, although was not affected by nitrogen fertilizer rates and split application. Thus, it seams that this part has important role in current photosynthesis at post anthesis stage compared with dry matter remobilization. According to our findings, flag leaf in Tarom cultivar not only has no significant role in dry matter remobilization, but also act as a powerful sink for photosynthetic assimilates.