简化施肥夏直播棉对密度和氮肥的响应

Responses of Cotton to Planting Densities and Nitrogen Rates under Direct Seeding in Summer with Simplified Fertilization

为研究夏直播棉花在增密、减氮和简化施肥(见花一次性施用)等措施下增密、减氮的适宜范围,2016-2017年在湖北省3个棉花主产区采用裂区设计研究了高密度和低氮肥对棉花生长发育、产量以及纤维品质等的影响。结果显示,种植密度从7.5万株/hm^2提高至9.0万株/hm^2时,棉株中上部果枝长度在2年中分别变短1.3和1.8cm,中部果枝第一果节长度分别变短0.5和0.6cm,单位面积成铃数增加9.0万/hm^2,生育进程、实收皮棉产量和纤维品质均无显著差异;氮肥用量在135~255kg/hm^2范围内,棉花理论产量、实收产量、纤维品质和农艺性状均无显著差异。在本试验设置的高密度和低氮肥范围内,简化施肥夏直播棉可获得比较稳定的产量和品质。具体而言,湖北省棉花主产区实施这一种植模式时,密度可增至9.0万株/hm^2,氮肥用量可降至135kg/hm^2。

In order to explore the suitable planting density and nitrogen rate of direct seeding cotton in summer under the measures of increasing density,reducing nitrogen and simplifying fertilization(One-time fertilization at first flowering),split plot design trail was conducted to explore the effects of planting density(75000 and 90000 plant/ha),nitrogen rate(135,195 and 255 kg/ha)and their interaction on agronomic traits,yield and fiber quality in three major cotton production areas of Hubei province in 2016 and 2017.The results showed that when the planting density was increased from 75000 to 90000 plant/ha,the length of middle-top fruiting branches decreased by 1.3 and 1.8 cm respectively,the length of first fruit internode of fruiting branch decreased by 0.5 and 0.6 cm respectively in two years;the number of bolls per unit area increased by 90000 plant/ha;but there was no significant difference in agronomic traits,harvest lint yield and fiber quality.There was also no significant difference in theoretical lint yield,harvest lint yield,fiber quality and agronomic traits across nitrogen fertilizer from 135 kg/ha to 255 kg/ha.Under the pattern of the cotton direct seeding in summer with simplified fertilization,cotton could achieve a relatively stable yield within the range of high density and low nitrogen fertilizer set up in this study.When this planting pattern was implemented in the main cotton producing areas of Hubei province,the density can be increased to 90000 plant/ha and the nitrogen fertilizer reduced to 135 kg/ha.