| The paper studied on soybean cytoplasmic-nuclear male-sterile line .In order to open out the cytological and genetic characteristics of soybean cytoplasmic-nuclear male-sterile line, four question have been discussed: the appearance and identification of W931A, when and why abortion took place , photosynthesis physiological basis of heterosis, biological, characteristics relating to crop yield. While demonstrated the feasibility in the utilization of heterosis, scientific theory will be provided soybean genetics and breeding. The main results as follow: 1. The abortive characteristics of soybean cytoplasmic-nuclear male-sterile W931A I2-KI dying testing and pollen germination percentage indicated that W931A aborted completely and male sterility was high and quite stable. Result of FMR confirmed that male-sterile W931A's stigma vitality was as well as maintainer W931B.This is to say, Though W931A can not formed functional pollen ,it may receive foreign pollen to accomplish fertilization as well as pod setting and finished the whole reproductive growth finally. The sterility of W931A is stable. Sterility can be prevented from transformation if some measures were adopted accordingly. The abortive characteristics assured the stability in cross-fertilizing and provided qualification on cultivating high pure hybrid. 2. The cytological reasons for cytoplasmic-nuclear male-sterile line W931A's abortion Two causations were found in the research: first of all , abnormal callose arose foul-up in the microspores; Secondly, if alimentation of accommodation was hindered, the pollen can not develop all right. 3. Photosynthesis physiological basis of hybrid F1 HS9816's yield heterosis There was a positive correlation between photosynthetic capacity and crop yield. While photosynthetic capacity is measured by three indexes: net photosynthesis rate, transpiration rate and stomatal conductance. In the different development stages, the author compared HS9816 with ZD20 (CK) and found that photosynthetic capacity of hybrid F1 HS9816 was better than ZD20 (CK). The maximal difference occurred in podding. By scaling the three indexes on a whole day of podding, the result indicated that HS9816 possessed stronger resistance than ZD20 (CK) when water stress and higher light intensify happened. The characteristic guaranteed dry matter accumulation of hybrid soybean and formed physiological basis on yield superiority. 4. Yield superiority performance and developmental prospects of hybrid F1 HS9816 Soybean hybrid F1 HS9816, which was produced by uitilized soybean cytoplasmic-nuclear male-sterile line W931A as mother parent, has special agronomic characters when compared with Normal soybean cultivar. HS9816 possess more branches and stronger stem, the number of its legumes is higher and it had better stress tolerance. The productiontrials demonstrated that the plot yield of hybrid F1 HS9816 is 4.419 kg, (yield per mu 220.95kg) , which is higher 15.62% than ZD20 (CK), whose plot yield is 3.822kg(yield per mu191.10kg). The author drew a conclusion that the effect of increase production was notable and cytoplasmic-nuclear male-sterile line W931A was provided with great applicational capacity on soybean production. 5. Feature of the paper In the experiment, several types of cytological techniques have been applied to study on the development of pollen in cytoplasmic-nuclear male-sterile line W931A and its maintainer W931B. As a result, the abortional phase was uncovered: Mostly, abortion of W931A's pollen happened at uninucleate microspores period, its cytoplasm and nucleus was abnormal and degenerated. Some pollens(about 10%), whose generative cell were rotund or ellipsoidal, showed that the development could carry through on binucleate period, however, these pollens were not functional as well. The result laid a cytological basis on the further research in genetic mechanism of soybean cytoplasmic-nuclear male-sterility.
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