STUDIES ON PHOTOPERIOD-SENSITIVE CYTOPLASMIC MALE STERILITY IN WHEAT

Five Chinese common wheat cultivars backcrossed separately with Aegilops crassa, Ae. juvenalis and Ae. vavilovii cytoplasm (all belongs to D² cytoplasmic type)have been studied in respect of its photoperiodic response to sterility. The results are asfollows:①Five nuclear donors varieties used as controls were sown in winter at Wuhan,and treatment with different light duration at different developmental stage hadno prominent effect on the sterility of pollens and the percentage of seed set. When they were sown at Harbin,they also produced seed set normally.②These alloplasmic lines showed complete or almost complete male sterility under 24 h long day condition from the beginning of spikelet formation to heading. At floret differentiation stage, under 24 hlong day condition the sterility of pollen and number of seed grains also distinctly decreased,but some alloplasmic lines showed reduction not so evident as that produced at the former stage.③Among different alloplasmic lines,the cytoplasm of Ae. juvenalis is most sensitive to the long day condition.while cytoplasm of Ae. crassa is the next,and the cytoplasm of Ae. vavilovii is the last.④15. 5 h long day treatment had some influence on the male sterility and reduction of percentage of seed set,but was not so large asthat appeared under 24 h long day condition. At the beginning of spikelet formation.theeffect of 15. 5 h long day treatment was more obvious than that treated at floret differentiation stage,which indicate that at floret differentiation stage the effect of 15. 5 h longday condition on the pollen abortion and causing sterility was greatly reduced.⑤Underthe same alloplasm condition,different nuclei showed different effects on the production of male sterility. ⑥The cytoplams of D² type could be used as important genetic resource for the production of "Photoperiod-sensitive cytoplasmic male sterility"(PCMS)of wheat,when it was used in combination with definite nucleus,it could be employed asa new path for hybrid wheat production,since only two lines-the PCMS and pollinator lines were reguired in this system.