长江流域麦/油后直播棉花播种时间下限研究

【目的】晚播、增密、减氮是长江流域棉花生产通过缩短生产周期来降低人工成本和物化成本的有效途径,适宜的播种时间是麦/油后直播棉花产量形成的重要影响因子,但是适宜的播期及晚播下限的研究未见报道。【方法】2018年和2019年在湖北省主产棉区4个试验点进行播期试验,试验设5个播期处理,分别为5月20日、5月25日、5月30日、6月4日、6月9日,在高密度、低氮条件下,研究不同播种时间对棉花生育进程、田间长势长相、产量和品质的影响。【结果】推迟播种可通过缩短播种出苗期和苗期加速棉花生育进程,全生育期缩短,纤维品质稳定。但是,随播期推迟,伏桃数量、单株铃数、单位面积成铃数、籽棉产量及成熟期吐絮率下降。特别是过迟播种,单位面积成铃数、10月20日吐絮率及产量会显著下降。【结论】长江流域相似棉区麦/油后直播模式最适播期建议在5月25日左右,以不晚于6月4日为宜。

Study on the limitation of late sowing date on cotton planted after wheat/rape in the Yangtze River Basin

Objective] Late planting, increasing density and reducing nitrogen input are effective ways for cotton production in the Yangtze River Basin to reducing input costs through shortening the production cycle. However, the appropriate sowing date is an important factor of cotton production in the mode of sowing after wheat or rape. Method] A series of sowing date experiments with five sowing date treatments, named 05-20, 05-25, 05-30, 06-04, 06-09, were carried out at four sites of the main cotton-producing areas of Hubei province to study the effects of different sowing times on the growth process, field appearance, yield and quality of cotton in 2018 and 2019. Result] The results showed that the growth process of cotton was accelerated through shortening the sowing-emergence period and the seedling period; the whole growth period was shortened, and fiber quality of cotton was stable with postponing sowing. However, with the delay of sowing, bolls before Aug 15, bolls per plant, bolls per square meter, seed cotton yield and rate of opened bolls at maturity declined. Especially, when the sowing date is too late, the number of bolls, rate of opened bolls and yield would be significantly reduced. Conclusion] The suitable sowing date for cotton production in the mode of wheat or rape continuous cotton in the Yangtze River Basin is recommended to around May 25, but no later than June 4.