Photoperiod-sensitivity index of five parents and ten F1 hybrids of rice under natural daylength

Abstract

Simple linear regression coefficients of days to flowering on eleven planting dates (from May 14 to October 17, 1986) were used as an index to show the degree of photoperiod-sensitivity of rice plants. The genotypes which had photoperiod-sensitivity index close to zero was considered photoperiod-insensitive. The genotypes which showed photoperiod-sensitivity index lower than zero but not less than -0.35 was considered weakly photoperiod-sensitive. The strongly photoperiod-sensitive genotypes had photoperiod-sensitivity index less than -0.35.