The effects of the photoperiod-insensitive alleles, se13, hd1 and ghd7, on yield components in rice

Flowering time is closely associated with grain yield in rice (Oryza sativa L.). In temperate regions, seasonal changes in day length (known as the photoperiod) are an important environmental cue for floral initiation. The timing of flowering is important not only for successful reproduction, but also for determining the ideal balance between vegetative growth and reproductive growth duration. Recent molecular genetics studies have revealed key flowering time genes responsible for photoperiod sensitivity. In this study, we investigated the effect of three recessive photoperiod-insensitive alleles, se13, hd1 and ghd7, on yield components in rice under Ehd1-deficient genetic background conditions to ensure vegetative growth of each line. We found that se13-bearing plants had fewer panicles, hd1-bearing plants showed decreased grain-filling percentage, and ghd7-bearing plants appeared to have fewer grains per panicle and fewer secondary branches. Our results indicate that the pleiotropic effects of photoperiod-insensitive genes on yield components are independent of short vegetative growth. This will provide critical information which can be used to create photoperiod-insensitive varieties that can be adapted to a wide range of latitudes.