Effects of the Dwarfing Gene Originating from ‘Dee-geo-woo-gen’ on Yield and its Related Traits in Rice

Abstract

Effects of the dwarfing gene sd1 originating from the Taiwanese rice variety 'Dee-geo-woo-gen' on yield, yield components and other traits were investigated using two isogenic lines, T d and S d , and their respective parental varieties, 'Taichung 65' (T65) and 'Shiokari'. At Kochi University, T d and T65 were grown at three fertilizer levels in 1998, and at one fertilizer level in 1995. S d and 'Shiokari' were grown at one fertilizer level at Hokkaido University in 1996. Yields of T d and T65 increased as the fertilizer level was increased in 1998. The yield of T d was lower than that of T65 under all four growing conditions. Similarly, the yield of S d was lower than that of 'Shiokari'. In spikelet number per panicle, T d and S d were significantly smaller than their respective parental varieties under all growing conditions. In panicle number per m 2 , differences between T d and T65 were nonsignificant under all growing conditions. In this trait, S d was larger than 'Shiokari'. In ripened-grain percentage, T d was higher than T65. In 1000 grain weight, on the other hand, T d was smaller than T65 under all growing conditions except that in 1995. In these two traits, however, S d and 'Shiokari' were similar to each other. T d and T65 were similar to each other in length and width of spikelet. To sum up, the lower yields of T d and S d were mainly due to their small numbers of spikelets per panicle in comparison with their respective parental varieties. In spikelet number per m 2 and in sink size, T d and S d were smaller than their respective parental varieties, indicating that sd1 decreases sink size. In LAI and leaf weight per m 2 at the 80%-heading stage, T d and T65 were similar to each other, indicating that sd1 has almost no effect on the total amount of photosynthetic organ.