Effects of Different Planting Densities on Agronomic Traits and Yield Components of Hybrid Cotton

Taking Xiangzamian No.8 as the material to study the differences of growth period and the variation of some agronomic traits of hybrid cotton and their impacts on yield components under different planting densities in Changde of Hunan from 2008 to 2010.The results showed that in growth aspect,there was no difference before squaring stage,and each growth period delayed with increasing planting density after squaring stage but the difference was not big;changes of agronomic traits generally consistent with the law that with increasing planting density,the first fruit with minor bits and plant height increased,but fruit branch number,fruit node number and section number of bolls per plant reduced;from the aspect of yield component per unit area,with increasing planting density,boll number and ginning outturn showed a decreasing trend,single boll weight and yield of seed cotton and lint all decreased.In which,the treatment with planting density of 21 000 shoots/hm2 had the most boll number,the highest single boll weight and the highest yield of seed cotton and lint;the treatment with planting density of 12 000 shoots/hm2 had the least boll number and the lowest yield of seed cotton and lint.Therefore,in year with normal weather conditions,the 21 000 shoots/hm2 was the best planting density;but in drought year,it may appropriate to increase the density but not more than 30 000 shoots/hm2.