During 2 growing seasons (Spring 2010 and Summer 2011), at the practical center of Thai Nguyen University of Agriculture and Forestry, 2 experiment trials had been carried out to find the effect of planted density to the growth, development and yield of some upland rice varieties. The experiment consist of 4 planted densities (40,45,50,55 hills/m2) and 5 upland rice varieties. The results showed that planted density effecting significantly to seedling capacity (maximum seedling number, reproductive seedling number) of 5 trial upland rice varieties at both growing seasons at 95 percent level
different growing density effected significantly to LAI and dry matter of upland rice
LAI can bee reached highest values at density of 50 hills/m2 and lowest at 55 hills/m2 while density of 40 ones produced highest dry matter. Planted density tended to effect negatively to the percentage of filled grains/panicle and harvested yield. High planted density reduced these criteria. Thus, it is to suggest that suitable planted density from these upland rice varieties are from 40-50 hills/ m2.