| In this experiment, we used the cytoplasmic male sterile lines of stable fertility,maintainer lines and thermal-sensitive male sterile lines and restorer lines as materials, studied the propagation, seed production system, and the restorability and the heterosis. The results suggested as follows:1 Selection of the Gibberellin Sensitive StrainsThe male and female parents must have a certain height difference in order to improve the yield of propagation and hybrid seed of CMS lines. However, there was no difference in the height of the male and female parents in CMS lines propagation; in the process of seed production, we also encountered the problem that the restorer lines'height was similar to the male sterile lines'. In this study, we adopted the method of gibberellin spraying to increase the height of 56 excellent wheat strains, excellent results were achieved. All tested strains showed some sensitivity to gibberellin, the height of the tested lines increased 2-16cm after spraying gibberellin; but different strains had different sensitivity to gibberellin.2 Height Reduction of the Male Sterile Lines by Dressing Seed with Uniconazole Powder If the cultivated maintainer or restorer lines were insensitive to gibberellin, or the height of the restorer lines used in seed production was low, and the height of the male sterile lines was high, we could increase the height difference between the male sterile lines and the maintainer or restorer lines by reducing the height of the male sterile lines. In Zhanjiang, the sensitivity to uniconazole was different among the male sterile lines. We could mix seeds by uniconazole powder with the doses of 30mg/kg or 40mg/kg when the varieties that were taken as the maintainer or restorer lines were insensitive to gibberellin.3 Hybrid Seed Production(1) There were significant differences of the relative outcrossing rate and seed yield among different combinations.(2) The height difference between the male and female parents had significant impact on the relative outcrossing rate. When the height of the restorer lines was higher than that of the male sterile lines, there was positive correlation between the height difference of the male and female parents and the relative outcrossing rate of the combinations. When the height of the restorer lines was lower than that of the male sterile lines, there was negative correlation between the height difference of the male and female parents and the relative outcrossing rate of the combinations.(3) Horizontal distance of the male and female parents was closely connected with the relative outcrossing rate. There was significant difference of the relative outcrossing rate between border and interior row of the male sterile lines, and this difference was correlated to the height difference between the male and female parents.4 The Restorability and the Heterosis of the Male Sterile Lines(1) We tested the restorability of 6 wheat strains and found that the male sterile lines tested could be restored or partially restored only by Qianmai16. There was significant difference of restorability among the male sterile lines by Qianmai16, the seed setting rate of F1 in cross of Improved 5418A and 1360/S2110-2-4A with Qianmai16 reached to 70%, the 982 series male sterile lines could only be restored by Qianmai16 partially. The restoring source of the male sterile lines has broadened than unimproved lines.(2) In the hybrid combinations of each male sterile line and Qianmai16, more than half of combinations'yield of per plant surpassed the male parent Qianmai16, which showed some advantage in yield. In the aspect of advantage in yield components, effective panicle number of per plant and thousand grain weight of each combination were higher than that of the male parent Qianmai16, which showed excellent heterosis. In the aspect of qualitative characters, the result didn't show strong heterosis, and further study is required. |
