Effect of Sowing Date on Fertility and Fertility Difference among Tillers and Florets of Thermo-photo-sensitive Genic Male Sterile Wheat(Triticum aestivum L) Line C338S

The discovery of thermo-photo-sensitive genic male sterile(TGMS) wheat opened a new way of heterosis utilization in wheat.In this paper,the effect of sowing date on fertility and fertility difference among tillers,spikelets and florets of TGMS wheat were studied by sowing date tests in the field conducted for many consecutive years using TGMS line C338S as materials.The results indicated that TGMS wheat line C338S showed male fertility alternation phenomenon in the patterns of completely sterility,highly sterility,semi-sterility,lower sterility and normal fertility under different environmental temperature and photoperiod conditions at the formation and development stages of microsporogenesis through sowing at different dates.The fertility alternation was stable in different years.The fertility differences were observed among the main shoot and the tillers of the TGMS line,among the spikelets at different position of the spike as well as among the florets at different position of spikelets.The seed setting of the tillers developed later were higher than that of the main shoot and the tillers developed earlier for the TGMS wheat line.The frequencies of the fertile pollen grains and the fertile florets in the spikelets of the lower part of spikes were higher than that in the middle part of spikes,and that in the upper part of spikes were the lowest.The seed setting rate of the third and the fourth florets were higher than that of the first and the second florets of the sterile plants of TGMS wheat line sowed earlier,but it was reversed in the fertile plants of TGMS wheat sowed later.These differences might mainly result from the difference of the environmental temperature and photoperiod conditions during the thermo-sensitive period to fertility stages of TGMS wheat,and the competition ability to nutrient among the tillers,spikelets and florets.