应用PP333延缓杂交水稻亲本的抽穗期

从1986年至1988年以7个亲本为材料在4个试验点的研究得知:1、在幼穗分化第5或6期施用PP333可延缓水稻抽穗期;2、不育系对PP333的反应较恢复系敏感,3、在0—200ppm浓度范围之内,pp333浓度越高,延缓效果越显著;4、一次施用200ppmpp333可使不育系齐穗期延迟5天,效果比较好,又省药物和人力;5、pp333对千粒重无不良影响,但增加包颈率、减少饱粒数;6、50—100ppm赤霉酸可逆转pp333的延缓效应;7、在生产上,建议根据实际情况,灵活应用赤霉酸和pp333,使花期相遇,提高制种产量.

USING PP333 TO RETARD THE HEADING OF PARENT PLANTS IN HYBRID RICE

Flowering synchronization in parent plants is a key problem in increasing hybrid rice seed yields. PP333, plant growth retardant, was used to investigate the retardation of heading for 7 lines of parent plants in 4 trial sites during 1986-1988. Results obtained show that application of PP333 at pollen mother cell formation stage or pollen mother cell meiosis stage in panicle could retard rice heading; the retard response to PP333 by cytoplasmic male sterile line was more sensitive than by restorer line; the higher concentration of PP333 at the range of 0-200 ppm, the stronger retardative effect occured; spraying PP333 at 200 ppm at one time delayed 5 d in 80% of heading of cytoplasmic male sterile line. This was the best measurement because it showed higher retardative effect but less amount of retardant and labour; PP333 did not influence the 1000-grain weight, but caused poor panicle exser-tion so that it decreased the grain number per panicle; GA 3 solution at concentration from 50 to 100 ppm countered the retard effect of PP333; we suggest that, in field condition, according to the heading of parent plants being early or late, the application of PP333 and GA 3 could flexibly adjust the 80% of heading to synchronize flowering which should be conductive to higher crossed seed set.