江汉平原免耕直播晚稻适宜播期探讨

目的]探索江汉平原免耕直播晚稻的最佳播期。方法]在荆州市对晚稻品系A进行6个不同播期的免耕直播试验,筛选晚稻的适宜播期。结果]播期在5月31日~6月20日,每推迟10 d,抽穗期相应提前6 d;播期在6月20日~7月20日,每推迟10 d,抽穗期相应推迟5~10 d。播种延后的天数与抽穗期、全生育期、播种-齐叶期活动积温均呈二次曲线关系。6月30日以后的播期处理,穗长、有效穗数、每穗总粒数和结实率呈减小趋势,播期越迟,减小幅度越大。6月10日以后的播种处理,实际产量呈递减趋势,播期推迟到7月10日以后,产量减产510.0~1 252.5 kg/hm2。结论]江汉平原免耕直播品系A的适宜播期为6月10日以前,6月30日左右播种结束。

Study on the Optimum Sowing Day with No-tillage and Direct Seeding of Late-season Rice on Jianghan Plain

Objective] The objective of the research was to optimize the sowing day of late-season rice under no-tillage and direct seeding on Jianghan Plain.Method] With late-season rice strain A as tested material, the optimum sowing day was screened out by no-tillage and direct seeding trails of six different sowing days.Result] From May 31th to June 20th,a 10-day delay of sowing stage could postpone the tasseling stage by 6 days correspondingly,while a 10-day delay of sowing stage,from June 20th to July 20th,could put off the corresponding tasseling stage by 5-10 days.The number of delaying day after sowing had quadratic function relationship with the effective accumulated temperature of tasseling stage,whole growth period and the stage from sowing day to full leaves stage.After June 30th,the length of panicle,effective tillers number,spikelets per panicle and seed setting rate were decreased with the delay of sowing day.The later sowing day was,the more they dropped.The actual yield was decreased with the delay of sowing day after June 10th,and the yield had a decrease of 510.0-1 252.5 kg/hm2,when the sowing day was delayed after July 10th.Conclusion] The optimum sowing stage of rice strain A under no-tillage and direct seeding on Jianghan Plain was before June 10th and the seeding should be finished before June 30th.