열대지역에 적응하는 온대 자포니카 벼 품종 개발을 위한 이삭형질 개선의 육종 방향을 제시하고자 한국과 필리핀 우기재배에서의 이삭형질 변이 및 특성에 대해서 조사하였다. 이삭형질의 변이는 2차 지경 착생립수가 차이가 가장 많이 나는 형질이었고 1차 지경 평균립수가 가장 적게 나는 형질이었다. 2차 지경 관련 형질이 1차 지경 관련 형질보다 수당립수와의 상관관계가 높았다. 지역간 차이가 많이 난 형질은 2차 지경 립수, 2차 지경수, 수당립수, 총지경수 순
This study was conducted to investigate characteristics and variations of rice panicle traits for breeding temperate japonica varieties adapted to tropical environment. Eleven panicle traits were investigated from nine Korean rice varieties cultivated in Korea and wet season of the Philippines. Tested cultivars were composed of six temperate japonica varieties, three Tongil-type varieties, and one indica variety bred in the Philippines. The number of spikelets on secondary rachis branches (SRBs) was the most variable trait in both environments, while the mean number of spikelets on a primary rachis branch (PRB) was the least variable. Compared with PRB-related traits, SRB traits showed higher correlation with the number of spikelets per panicle. Compared with the plants grown in Korea, the number of spikelets on SRBs, the number of SRBs, spikelets, and rachis branches per panicle were decreased more than other traits in the Philippines. According to path analysis, the number of spikelets on SRBs per panicle affects the number of spikelets per panicle more than the number of spikelets on PRBs per panicle. Climatic factors such as growth duration, cumulative mean temperature, and integrated solar radiation were highly correlated with the relative rate of number of spikelets per panicle. To breed temperate japonica rice varieties adapted to tropical environment, it would be important to select lines which maintain proper growth duration and spikelets on SRBs in target region.