Effect of nitrogen on rice yield, yield components and quality parameters

Effect of nitrogen (N) fertilizer levels on yield and yield components of rice (Hashemi, Ali kazemi and Khazar) was investigated in an experiment as factorial in randomized complete block design (RCBD) with three replications in a paddy light soil at Guilan province, Iran, in the year 2008 to 2009. In this experiment, four treatments including: N1, control (no N fertilizer); N2, 30 kg N/ha; N3, 60 kg N/ha; N4, 90 kg N/ha were compared. Results show that total biomass (8386 kg/ha), grain yield (3662 kg/ha), plant height (127.9 cm), tillers m-2 (250.22), panicles m-2 (235.8) and total grain per panicle (103.8) reached the highest value at high nitrogen level. Among the varieties, the highest total biomass (7734 kg/ha), grain yield (3414 kg/ha), unfilled percent (20.16%) and total grain per panicle (78.2) belonged to Khazar. Significantly, tiller m-2 (250.83) and panicle m-2 (235.91) were obtained from Hashemi. Also 1000-grains weight against various studied varieties revealed that Ali kazemi produced maximum 1000-grains weight (28.99 g). Among the different N application levels, significant difference was observed in all quality parameters except gelatinization temperature (GT); the highest amylose content (AC) was obtained from treatment N1 and significantly highest gel consistency (GC) was obtained from treatment N3. In general, GC was increased with N-fertilizer application and only result was changed from N3 to N4 and was reduced. Whereas AC was reduced from N1 to N3, and the result was reversed from N3 to N4. Meanwhile, the interaction effect of variety × nitrogen fertilizer did not show significant difference between all quality parameters except of GC.   Key words: Nitrogen fertilizer, grain yield, yield components, dry matter production, quality parameters.