Effect of plant density of dry matter remobilization and grain yield for two local rice cultivars

To study the effect of planting density (11.11, 16 and 25 plants.m-2) on dry matter remobilization and grain yield of rice cultivars, Hasani and Hashemi, a field experiment in factorial layout based on randomized complete block design with four replications carried out at Rice Research Institute of Iran (RRII) in 2011. Results showed that the plant height, number of tillers.plant-1, biological yield, grain yield of main stem and other tillers, number of panicles.m-2, number of grain.panicle-1, number of filled grains.panicle-1, number of grains.m-2, grain weight, grain length and its width and dry matter remobilization efficiency were significantly differ between Hassani and Hashemi cultivars and the effect of density on grain yield, harvest index, secondary tillers and main stem harvest indices, the number of filled grain.panicle-1, grain density.panicle-1, dry matter remobilization, current photosynthesis rate were significantly different. Apart number of tillers.plant-1, other traits were increased with plant density. An increasing in plant density, increased the number of grains.m-2 and leads to increase in grain yield of rice cultivars. The average total grain yield (4853 kg.ha-1) obtained from 25 plant.m-2 and the main stem produced 791 kg.ha-1 (16.3%) of grain yield. Also, there was a significantly increasing in the current photosynthesis in grain filling duration with 3380 kg ha-1 in 25 plant.m-2 treatment and greatly enhance the total grain yield. The rice cultivars, Hasani and Hashemi, with an average of 59.8% and 39.3% in the current photosynthesis efficiency were significantly different. Grain yield of both rice cultivars increased alongside increase in current photosynthesis rate and the dry matter remobilization was less than the current photosynthesis. It seems that in order to increase the grain yield of rice, plant density should be increased for dry matter remobilization and current photosynthesis enhancement.