黄河流域棉区北部留叶枝棉栽培的适宜密度研究

Response of Cotton (Gossypium hirsutum) with Sympodial Branches to Plant Denesity in the North of the Yellow River Areas

以中等密度（6.0万株.hm^-2）下的传统整枝为对照,于2004—2005年研究了密度（1.5万-12.0万株.hm^-2）对留叶枝棉产量和品质的影响。结果表明,随密度增加,留叶枝棉的子棉产量和单位面积铃数先升高后降低,但在3.0万～9.0万株.hm-2范围内无显著差异;单株铃数、铃重和纤维的麦克隆值则随密度增加显著下降。中等密度下,留叶枝棉的子棉产量在降雨较少的2004年与对照相当,但在降雨较多的2005年减产13.4%。在黄河流域棉区北部,留叶枝棉栽培的适宜密度为6.0万株.hm-2左右,多雨年份要注意防止群体过大造成郁闭。

Field studies were conducted in 2004 and 2005 at Wuqiao experimental station,Hebei province,of China Agricultural University,to investigate the effect of plant density on yield and fiber quality of cotton with sympodial branches,with hybrid cotton Xinza2 and conventional cotton Guokang12 as materials.The results showed that there was no significant difference in seed cotton yield between cotton with and without sympodial branches at medium density（60000 plants.hm-2） in 2004,characterized by less rainfall.However,yield of seed cotton with sympodial branches significantly reduced 13.4% compared to that without sympodial branches in 2005,characterized by excessive rainfall during blooming stage,mainly due to fewer bolls per plant.Compared to Guokang12,Xinaza2 was less susceptible to rainfall.Additionally,the reservation of sympodial branches could decrease fibre micronaire value.With the increase of population density from 15000 to 120000 plants.hm-2,the yield of seed cotton with sympodial branches increased at first,while reached the peak at about 60000 plants.hm-2,then decreased.Nevertheless,there were no significant differences in yield among population density from 30000 to 90000 plants.hm-2.The change tendency of boll numbers per unit area with population density was similar to that of yield,and boll numbers per plant and boll weight reduced significantly with the increase of density.Moreover,high density could reduce the micronaire value of cotton.It was concluded that 60000 plants.hm-2 is appropriate for the cultivation of cotton with sympodial branches in the North of the Yellow River area,but it is necessary to avoid excessive vegetative growth during overcast and/or rainy period.