effect of nitrogen fertilizer rates on morphological traits, yield and yield components of three cultivars of rice

in order to study the effect of n fertilizer rates on morphological traits, yield and yield components of rice cultivars, a study was carried out in rice research institute of rasht, iran during 2009. it was a two-variable factorial experiment based on a randomized complete block design with three replications. the first factor was nitrogen fertilization at four rates of 0, 30, 60 and 90 kg n ha-1 and the second factor was rice cultivar at three levels of hashemi, ali-kazemi and khazar. the results of analysis of variance showed that n fertilizer rates did not significantly affect on panicle length, grain number per panicle, 1000- grain weight and harvest index but significantly affected plant height, tiller number per m2, panicle number per m2, grain yield and biological yield. means comparison showed that as n rate was increased from 0 to 90 kg ha-1, plant height, tiller number per m2, panicle number per m2, grain yield and biological yield increased by 12.7, 27.6, 32.6, 84.5 and 61.6%, respectively. the cultivar significantly affected morphological traits, panicle number per m2, grain number per panicle, 1000-grain weight, grain yield and biological yield. the results indicated that cultivar of khazar had the highest potential of grain yield (3424.5 kg ha-1). in total, application of 90 kg n ha-1 and cultivar of khazar treatment was better for having the maximum production under the conditions of the current study.