Effect of nitrogen fertilizer levels on Fe and protein content, grain breakage and grain yield of rice (Oryza sativa L. cv. Khazar)

In order to evaluate the effect of nitrogen fertilizer levels on Fe and protein content and breakage of rice grain (cv. Khazar), a field experiment was conducted at Rice Research Institute of Iran, in 2011. Nitrogen fertilizer levels (10, 20 and 30 kg.ha-1) were applied according to three chlorophyll meter (SPAD-502 reading threshold) (36, 38 and 40) on fully developed leaf of rice plant. Result showed that the nitrogen fertilizer levels had significant effect on grain Fe and protein content and grain breakage. Maximum protein and Fe content was observed in S40N30 (SPAD40+ 30 kgN) treatment (9.46% and 12.43 mg.kg-1, respectively). Grain breakage reduced in accordance to nitrogen fertilizer increment and there was a negative correlation between nitrogen fertilizer application and grain breakage. Minimum rate of grain breakage was observed in higher nitrogen treatment without any fissure. Maximum grain yield and milling recovery was also observed in S40N30 treatment (5960 kg.ha-1 and 69.93%, respectively) which that 2.5% higher than recommended fertilizer treatment and 14.6% higher than control. It seems that split application of nitrogen fertilizer may improve rice grain protein content, reduce rice grain breakage and enhance rice grain quality and milling recovery.