| Two-line hybrid wheat has broad production prospects for increasing food yields. To make clear the fertility transfer law of photo-thermo-sensitive male genic sterile wheat and the critical temperature of fertility transferation are valuable for the hybrid wheat's production. Taking thermo-photo-sensitive male sterile wheat line BNS as the experimental material and Bainongaikang58(BNK58) and Yangmai13(YM13) as the check varieties, interval sowing time trials were conducted in Changsha, Hunan province from2010to2011in this paper. The results showed as followers:(1) BNS pollen sterility examination with microscope:the pollen stertility changed as the sowing date differed and showed a trend from typical abortion→spherical abortion→stained abortion→fertile→stained abortion. The pollens were mainly typical abortion in prophase, while the pollens from the plants which flowering after late April mainly showed spherical abortion. The pollen abortion rates were all100%and the self-seed rate was zero when BNS sowed from late September to early November. Then the fertility stared to change and the pollen abortive percentage decreased below90%when the sowing dates ware between January10and November18. When the sowing dates were among late November and early January the pollen abortive percentage were gradually decreased, manifested as normal fertility. Moreover, the sterile degree of BNS rose again and the self-seed rates showed gradually decreasing when seeding after February. In sum, BNS had a stable and complete male sterility with100%of pollen abortion rate when the seeding dates were among late September to November2in Changsha, when can be recommended for its hybrid seed production.(2)BNS's sterility sensitive phase and the critical temperature of fertility alteration: Daily mean temperature was the main factor affected the fertility alteration, while sunshine hours and precipitation were assistant factors. The fertility sensitive period of BNS was from8d to Id before heading since the daily mean temperature during this period was tightly linked to self-seed rates, their correlation coefficient reached to0.8580(γ=0.8580**). During this period, only if daily mean temperature lower than the critical temperature in more than four consecutive days would cause the fertility of BNS decrease. During the sensitive phase, BNS was highly sterile if the daily mean temperature <11.7℃. If the daily mean temperature ranged from11.8℃to13.6℃in the period, BNS showed fertility change. BNS was steady fertile when daily mean temperature higher than14℃during the sensitive phase.(3)The fertility alteration discipline for BNS:the trend of fertility alteration of BNS was from complete sterility to semi-sterility, normal fertility and then partial sterility.(4)The performance of agronomic characters and yield traits of BNS line in different sowing dates:As the sowing date delayed, BNS's whole growth period, the stage of jointing, heading and maturity were all gradually shorten; and plant height, ear length and the length of ear stem out of flag leaf sheath were reduced, respectively.1000-grain weight of BNS line showed a trend of lower-higher-lower as the sowing date delayed after November10, while there was no seed set among the sowing dates from23November to2February.(5)The manifestations of F1hybrid of BNS line in Changsha: the agronomic characters of hybrid tested were better than the mother parent BNS, such as compact plant type, vigorous growth, and haleness. The F1's1000-grain weight showed a trend from low to high and then low. However the fertility alteration of F1plants was similar to that of mother line BNS. In different sowing date, the pollen fertility was displyed a tendency as "typical abortion→fertile→typical abortion ". The trend of F1fertility alteration is from high sterility to normal fertility, and then partial sterility. When the sowing dates among early November to early January, F1's pollen sterility was lower than52.9%, and the seed setting rates was34.8-73.3%and similar to that of check varieties, which could be recommended as the proper time to sowing F1hybrid for commercial production in Changsha. |
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