عنوان مقاله [English]
This study was conducted to determine the most suitable plant density on the yield and yield components of
rice varieties. A factorial experiment based on a randomized complete block design with three replications was performed in Astara region in 2008. Two factors were considered in this experiment, consisting of plant density at five levels (1, 3, 5, 7 and 9 seedling in each hill) and five varieties (Hashemi, Dorfac, Line 338, Neda and Sepidrood). Physiological and morphological characteristics like plant height, panicle length, 1000 seeds weight, number of tillers in plant, number of kernel per panicle, number of empty and filled seeds per panicle, paddy yield in hill, biomass in a hill, harvest index, biomass in eaach plot, paddy yield per plot and paddy yield per hectare were measured and recorded. The results showed significant differencees between varieties for plant height, length of panicle, number of tillers per plant, number of seeds per panicle, number of filled empty seeds per panicle, biomass at hill and plot levels, paddy yield at plot and hectare levels. Indeed, significant differencees were found between plant densities for length of panicle, number of tillers per plant, number of seed per panicle, number of filled seeds per panicle, harvest index, biomass per plot, yields (plot and hectare). Interaction effects of genotype and plant densities were also found, indicating significant differences for the panicle length, 1000 seed weight, harvest index, biomass of plot, paddy yield (plot and hectare). The highest grain yield (4809 kg/ha) was obtained for the three seedling density in a hill. In respect of yield production, there was no significant differencees between all varieties that ranged from 3962 to 4714 kg/ha, except the line 338 where produced the lowest paddy yield (2859 kg/ha). Sepidrood variety with nine and one seedlings in each hill presented the highest and the lowest yield, 6226.6 and 1372.2 kg/ha, respectively, among the varieties tested. It is concluded that plant densities of one seedling per hill for Neda and nine seedlings per hill for Sepidroud varieties are recommended..