| The botanical morphology characteristic, wide compatibility, critical sterility inducing temperature, out-crossing characteristics, combining ability, correlation between yield and main characters of F1, effect of mechanization of hybrid rice seed production by breeding parents with different grain types, screening and separating two types of seeds by physical methods were studied and discussed in the dissertation. The main results are as follows:1.4657S is a middle maturity indica rice with its duration from seeding to heading(DSH) about74-79days (breeding in summer). The plant height is about54.85cm with compact plant type. Stems with five nodes were short. The average effective panicle number is about13, with21.78cm in ear length,0.88cm in neck-panicle node and about180grain number per panicle. And it owned the character with erect panicle type, bigger tassel and more grains, higher ratio of grains to leaf. The length and width of the flag leaf was about22.38cm1.18cm. And the opening angle was less than10°of the thick flag leaf, with deeper green color, which was erect in the whole growth period. Grain length and length to width ratio were7.00mm and3.65of4657S,which1000-grain weight was lower than13g. Stem clasping length was about6cm, with about18glumous flower enclosed, in sterility period.2. The outcrossing characteristics was excellent. Percentage of spikelet flowing before noon of4657S was about73%, which would be promoted increased by gibberellin. And stigma exertion rate was68%. As for sensitive to gibberellin, it could release the rice ear enclosed in the leaf sheath with gibberellin at300-450g· hm-2.4657S was with weak wide-compatibility. In test varieties analysis with standard testers of wide-compatibility, the spikelet fertility of F1was close to75%.3. The critical sterility inducing temperature (CSIT) was under23.5℃in Changsha with long light in summer. And the rate of stained pollen was83.5%with irrigation consecutively with cold water running-cold water at22.5℃. the self-fruitful rate was76.2%when propagated sterile line seeds in Hainan.4.4657S expressed good combining ability. Grain per spike, effective panicle number, growth period and yield per plant had high general combining ability, which was low of plant height, seed setting rate,1000-grain weight, grain length, grain width and length to width ratio. The yield per plant was positively correlated with Grain per spike, effective panicle number, seed setting rate and1000-grain weight in rice cross of4657S.5. According to the seeding ratio of1:5,1:10,1:15,1:20,1:25and1:30, seed production by mixed sowing(SPMS) was carried out with4657S and R838. The results showed that gibberellin at300g· hm-2would get rid of the leaf sheath, and then made the restoer30cm higher than male sterile line. The treatment of1:5was best in seed setting rate, but worst in yield. However, it was the best in yield of the treatment of1:25.6. The effect of separating the two types of seeds, which were sowed and harvested together, was very good. After the third separation, hybrid seed purity would reach more than99%, which was up to the national purity standards. |
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