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

본 시험은 호남평야지에서 밀-벼 이모작 재배시 벼 폿트묘에 알맞은 적정 재식밀도를 구명하기 위하여 수행하였다. 폿트묘 재식밀도가 낮을수록 줄기긱경이 굵어졌으며, 최고 분얼기의 단위면적당 분얼수는 재식밀도가 높을수록 많았다. 간장은 관행 산파묘보다 폿트묘가 더 컸고, 재식밀도가 낮을수록 간장이 더 크게 나타났으나, 이삭길이는 재식밀도별로 유의한 차이를 보이지 않았다. 이삭수는 재식밀도가 높아질수록 단위면적당 이삭수가 많아지는 경향이었다. 등숙비율 및 천립중은 육묘방법 및 재식밀도 사이에 유의한 차이가 없었다. 백미수량은 재식밀도별로 보면 폿트묘 18.9주가 $5.43\;t\;ha^{-1}$ 로 관행 $5.18\;t\;ha^{-1}$ 보다 5% 증수하였다. 완전미 비율은 폿트묘 25.3주 이앙구에서 다소 낮았고, 육묘 방법간에 차이는 없었으나 재식밀도 간에는 다소 차이가 있었던 반면, 아밀로스 함량은 재식밀도 간에 유의한 차이가 없었다. 밀-벼 이모작 재배시 보통기보다 늦게 폿트묘를 이앙하는 경우 적절한 재식밀도를 선택하는 것이 영농에 도움이 될 것으로 보인다. 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.