Genotypic differences for flowering behaviour in different varietal types in rice (Oryza sativa L.)

摘要

Most of the rice hybrids presently being cultivated in India and else where are of inter-varietal (indicalindica) types and have about 15% yield superiority over the HYVs of corresponding maturity duration and grain quality when grown under similar production condition. However, the pace for adoption of these hybrids is rather slow in India which is mainly attributed to their inadequate yield superiority. Marginal yield advantage in these hybrids is due to lower genetic diversity among their parental(indicalindica) combination (Renhua ef al, 1998). To make rice hybrids economically more attractive to farmers there is a need to further enhance their yield heterosis to 25-30% level through development of inter-subspecific (indical japonica or tropical japonica) hybrids popularly known as super rice hybrids (Yuan, 1994). However, when too diverse parents such as indica and japonica are involved,difference in the flowering habit of those parental lines may pose problems in commercial hybrid seed production (Ikehashi ef al, 1992). For a successful hybrid seed production it is essential that the two parents have satisfactory level of synchronization with respect to the date of flowering and the time of anthesis.