A Survey on the Morphological Effects of Rice Promising Lines (Oryza sativa L.) In Response to the Changes in Planting Density and Nitrogen Content

In order to study physiological indices and different nitrogen fertilizer and plant density effect on yield and yield components in promising lines of rice an experiment was conducted during 2009 at Rice Research Institute of Iran (Rasht). Experiment was arranged as factorial based randomized complete block design with three replications. Nitrogen fertilizer at four levels (0, 100, 200 and 300 kg net nitrogen ha-1), planting density (30×15 and 25×25 cm) and promising lines of rice (416, 203 and line 2 Hybrid) were the treatments. Results showed that different nitrogen fertilizer had significant effect on different traits such as grain yield, grain number per panicle, panicle number per unit area, harvest index, fertile tiller number and fertility number. Interaction effect of fertilizer and density showed that highest grain yield was recorded when rice genotypes were transplanted as 25×25 or 30×15 cm with 200 kg net nitrogen ha-1. Maximum grain number per panicle, also, was belonged line 2 Hybrid. In terms of harvest index, fertility percentage and fertile tiller number, the highest amounts were obtained when line 416 planted with 30×15 cm plus 200 or 300 kg N ha-1application. Results showed that most treatments had significant effect on physiological indices. Accordingly, crop growth rate and leaf area index showed highest significant probability in terms of different factors interaction. Adversely, relative growth rate did not show significant response. Results showed that maximum LAI was belonged to line 203 with 100 kg net nitrogen ha-1. Crop growth rate, however, was highest in line 2 hybrid with 300 kg N ha-1 and net assimilation rate for line 416 with 200 kg N ha-1. Generally, planting density of 25×25 in all studied lines had the higher CGR. Furthermore, grain yield had a significant and positive correlation with panicle number per unit area (r=0.59**), fertile tiller (r=0.53**) and harvest index (r=0.47**), however, grain number per panicle showed negative and significant (r=-0.39**) correlation. Among traits LAD and CGR had a positive and significant correlation (r=0.63** and r=0.3**, respectively) with total dry weight (TDW) but RGR had negative and significant (r=-0.25*) correlation.