Genetics of Photoperiod Response in Rice

Abstract

The genetics of sensitivity to day-length was studied in the F1 and F2 of hybrids between the japonica rice varieies, Fukoku, Gaisen Mochi and Zuihio and a number of indica varieties of rice, of different durations and photoperiod sensitivity. The data showed that the short duration and low photoperiod-sensitivity of Fukoku and Gaisen Mochi were dominant over the long duration and high photoperiod-sensitivity of the indica parents and of a wild rice studied, giving F2 ratios of 15 : 1 and 3 : 1. The corresponding Zuihio hybrids showed sensitivity and in the F2 insensitivity occurred as a recessive character in ratios of 1 : 3 and 1 : 15. The variety Zuihio, which is recorded in Japan to be sensitive to photoperiods, behaved almost as an insensitive variety at Cuttack. It is inferred that temperature, or some other environmental factor, affects the expression of photoperiod response and the present results were interpreted by assuming that the genes modifying photoperiod response showed segregation in the hybrids studied.