Study on the Optimum Planting Density of Pot Seedling for Mid-Late Maturing Rice Variety in Wheat-Rice Double Cropping System in Honam Plain Area

This experiment was carried out to determine the optimum planting density for rice pot seedling cultivation in wheat-rice double cropping system in Honam plain area. A mid-late maturing rice variety Chinnong was raised in pot seedling tray and conventional tray for 30 days, and then transplanted on June 25 in 2012 and 2013. Four different planting densities (15.2, 18.9, 21.6, and 25.3 hills per m 2 ) in pot seedlings were applied as treatment. Conventional tray seedling was implicated as control at a single planting density of 27.8 hills per m 2 . In this experiment, the number of effective tillers was increased as planting density increasing, but stem diameter was decreased. Pot seedling showed higher stem diameter and effective tillers than the control. Heading dates of pot seedling plots were not significantly different between the planting densities but 2 days faster than the control. Culm length, number of panicles, panicle length, and ripening grain ratio were higher in pot seedling compared to the control, but 1000-grain weight showed no significant difference. Milled rice yields in pot seedlings ranged from 5.19 to 5.43 t ha -1 , and the highest yield was observed in 21.6 hills per m 2 . Head rice ratios in pot seedlings and the controls were not significantly different. Above results on planting density of rice pot seedling cultivation would be applicable to wheat-rice double cropping and also to late transplanting cultivation of rice single cropping.