Study On Some Hereditary Properties Of The Dominant Semi-dwarf Rice

This paper deals with the dominant semi-dwarfism gene in three different aspects,such as effects on agronomic traits in rice, sensitivity to GA3 and apply in breeding for hybrid rice, The result followed: 1 Six tall and dwarf near isogenic lines was studied. The results indicated that the length of internodes were inhibited by the dominant semi-dwarf gene. And the length of internodes form the basal internode to the uppermost internode and panicle of dwarf near isogenic lines were 97.2%,53.3%,65.1%,61.9% and 94.7% of tall ones.The dominant semi-dwarf gene was no effects of the dominant semi-dwarf gene on the traits of days to heading,no. of spikelet per panicle and 1000 grains weight. The effective panicles per plant and spikelet fertility were increased by the dominant semi-dwarf gene, and the yield of dwarf near isogenic lines was higher than tall ones. 2 The response of Y98149 and Y98148 to GA3 at seedling stage and the shooting stage were studied. The results indicated that Y98149 was much more sensitive to GA3 than Y98148, the dominant semi-dwarf gene was sensitive to GA3. GA3 biosynthetic was inhibited by the dominant semi-dwarf gene and have effect on plant height. 3 To understand the influences of the semi-dwarf gene on F1 major agronomic traits, the level of two male sterile lines were identified. The results indicated that the lines level of combining ability were better than CK. We can obtained good combination from the semi-dwarf male sterile line cross with some parents. 4 the rice semi-dwarf mutant and derived dwarfness source to be tested for wide compatibility were crossed with both indica and japonica varieties and 40 combination was obtained. The results show that the average spikelets per plant of the F1 of "D5"× indica standard tester is 78.7%, the average spikelets per plant of the F1 of "D5"× japonica standard tester is 77.9% ,"D5" was partially wide compatible. As a consequence, The effects of the dominant semi-dwarf gene was studied deeply, the dominant semi-dwarf gene was sensitive to GA3, the dominant semi-dwarf gene in breeding for hybrid rice was discussed.