水稻雜種優勢之研究(1)水稻品種間雜種第一代優勢之初步測定

Abstract

1. Originally 160 cross-combinations were made between rice varieties but the serious cold temperature killed some of the F1 seedlings. Only 90 cross-combinations were used for studying the hybrid vigor of rice and its practical value in terms of grain yield. 2. The primarily test for the cold resistance showed that 65 cross combinations of F1 hybrids wee controlled by dominant genes, 19 cross-combinations were controlled by additive genes, and 40 cross-combinations were controlled by recessive genes. However, a further study on the heredity of rice resistant to low temperature will be necessary to clarify the genetic behavior. 3. The hybrid vigor in terms of the growth of plant height and number of tillers during the first five weeks after transplanting were obvious. However, the hybrid vigor were decreasing after the seventh weeks, especially the growth of plant height. 4. Most of the F1 hybrids showed earlier in heading than their early-maturing parents, though some cross-combinations showed later in heading than their parents. 5. Hybrid vigor in terms of grain yield showed that 44 cross-combinations produced more grain yield than their higher yield parents, mainly due to the increase of panicle number and spikelets per panicle. Among the F1 hybrids, H 276 (Taichung 176 x Taichung 150) and H 104 (Tainung 60 x Kwaugfu 1) showed the highest hybrid vigor, produces 60% more than the higher yield of their parents. Comparing with the commercial varieties, 31 cross-combinations produced more grain yield than Taichung 65, but only H 55 (Tainung 38 x Kwangfu 401) and H24 (Tainan 3 x Taichung 65) produced more yield than Tainan 3. 6. In the F2 generation, the variations of plant height and number of tillers among the various cross-combinations were small, but the variations of growth period were obviously different. The earliest maturing F2 hybrid was H 145 (Aikoku x Taichung 186) only 94 days. The latest hybrid was H 130 Pi No.2 x Kaohsiung 135) taking 129 days for maturity. Most of the hybrids showed unequal on grain maturity except H 145, H 83, and H 18. 7. The results of the grain yield trail between cross-combinations in F2 generation showed significant difference. Among the hybrids seven combinations including H 18 (Tainung selection 3 x Yoshino No.1) and H 276 (Taichung 176 x Taichung 150) produced promising yield in F2 generation as well as in F1 generation.