Shorter Days to Heading Increased Dry Weight Per Panicle of Short-Panicle Rice Cultivars

Abstract

To elucidate the factors that affect seed yield of rice cultivars with a short-panicle (SP) caused by a mutation in the SP1 gene, we grew 64 SP cultivars in paddy fields in 2015 to 2018 and transplanted 4 SP cultivars (‘Chugokushi224’, ‘Chugokushi225’, ‘Tsukisuzuka’ and ‘Tsukikotoka’) on 3 dates in 2018 in paddy fields at the Western Region Agricultural Research Center. We recorded days to heading (DTH), dry weight per panicle, panicle number and panicle dry weight per m². Dry weight per panicle contributed to panicle dry weight per m², but panicle number did not. Dry weight per panicle had strong negative correlations with DTH in all SP cultivars and in all transplanting dates when DTH, 80: dry weight per panicle increased with shorter DTH.