Evaluation of genetic variation of rice cultivars in response to different level of nitrogen

To investigate effect of nitrogen on the genetic variations and to identify the process of these variations and some main quantitative traits, this study has been carried out on rice plant. So, sixteen improved and local rice varieties were selected for each groups, and then 4 nitrogen levels for local varieties and 6 nitrogen levels included high yielding improved varieties and the spilt plot with 3 replication are adopted. The results indicated that significant differences on some important characters such as, panicle length and plant height in local varieties and panicle length, grain width, 1000- grain weight yield per plant, plant height, number of tillers and flag leaf length in high yielding improved varieties. Also. In response to nitrogen application there were some differences between local and high yielding varieties and traits. To evaluate the relative importance of different variations sources comparing the importance of nitrogen effect on local and high yielding varieties, the traits of panicle length, flag leaf length, number of tillers and Flag leaf width were ranked in higher degree of importance. Genetic variation was significant at 1% probability level for all traits with the exception of yield per plant. The variation coefficient of genetic variance of all characters were not stable over the N levels for high yielding varieties. Heritability for grain length and width, 1000-grain weight, and flag leaf length in local varieties was nearly high in 4 levels of nitrogen and the most amount of heritability was related to plant height of high yielding varieties. According to these results and the history of experimental, there are some degree of differences between local and high yielding varieties, so that, based on coefficient of variance of heritability in different levels of nitrogen. The high yielding varieties show higher degree of stability.