벼 담수직파재배에 있어서 적정립모수 설정

Optimum Number of Seedling Stands of Rice for High Yield in Direct Water-Seeded Culture

벼 담수직파재배에서 적정 파종양과 입모수 설정을 위하여 낙동벼와 삼강벼를 공시하여 5월 4일 작물시험장 답작포장에서 파종양을 달리하여 시험한 결과를 요약하면 다음과 같다. 1. 공시품종 모두 파종양이 증가할수록 최고분얼수는 많아졌고 유효경비율은 저하하였다. 2. 공시품종 모두 파종양이 증가할수록 유효분얼한계기는 앞당겨지는 것으로 나타났으며 3. 5kg/10a 파종구의 유효분얼 한계기는 6월 18일 전후이었다. 3. 단위면적당 수수는 공시품종 모두 파종양이 증가할수록 많아졌다. 수당영화수는 낙동벼에서는 파종양의 증가에 따라 차이가 없었으나 삼강벼에서는 감소하였다. 4. 파종양이 증가할수록 낙동벼의 등숙률은 떨어 졌으나 삼강벼에서는 차리가 없었다. 5.$m^2$당 적정 입모수는 삼강벼에서는 120개 정도, 낙동벼에서는 78개 정도이었으며 파종양으로 볼 때 삼강벼는 4kg /10a, 낙동벼는 2.7kg /10a 정도가 적당하였다.

This study was carried out to determined the optimum seeding rate and number of seedling stands per unit area for high yield with two varieties of rice, Nakdongbyeo (Japonica type) and Samgangbyeo (Indica x Japonica type), in direct water-seeded rice culture at Crop Experiment Station. Seeds coated with $CaO_2$ after germination were sowed at May 4 in 7 levels, such as 1.6, 1.8, 2.1, 2.7, 3.5, 4.0, 4.3kg /10a, and the number of seedling stands per square meter was adjusted to be 30, 40, 60, 80, 100, 120, 140 plants, respectively. The maximum number of tillers increased as the seeding rates increased, but the ratio of effective tillers decreased. The critical dates of effective tillering of tested varieties were delayed by the lower seeding rates, and the date was June 18 at the plot of seeding rate with 3.5kg /10a. The number of panicles per unit area increased in accordance with the increased seeding rates. The number of spikelets per panicle in Nakdongbyeo was not affected by the seeding rates, but in Samgangbyeo it decreased as the seeding rate increased. The optimum number of seedling stand per square meter appeared to be 78 in Nakdongbyeo and 120 in Samgangbyeo, respectively. It meant that the optimum seeding rates for Nakdongbyeo and Samgangbyeo were about 2.7 and 4.0kg /10a, respectively.