Effects Of Wheat-Cotton Cropping System And Nitrogen Rates On Nutrition Uptake And Utilization, Yield And Fiber Quality Of Cotton

Wheat-cotton cropping system is a major pattern in cotton region of Yangtze basin. Nitrogen is a important factor that control the cotton’s growth and development. Go into the effect of different cropping system and nitrogen rates on uptake and utilization of nitrogen, yield and fiber quality of cotton to taking the reasonable cultivation techniques, have a big significance. Taking two cotton cultivars Siza 3 and CCRI 50 as materials, the field experiment was conducted to study the effects of different cropping system (monoculture cotton, wheat-cotton intercropping, transplanted cotton after wheat, direct-seeded cotton after wheat) and nitrogen rates(0,300 and 450 kg/ha) on uptake and utilization of N,P,K and yield of cotton. The result show that:1 Effects of cropping system and N rate on yield and fiber quality of cottonThe dry matter accumulation of the reproductive organs and whole cotton plant of DM is the highest and the lowest is ZM. Nitrogen application improves the dry matter accumulation of the reproductive organs and whole cotton plant in different cropping system. The seed cotton Harvest index of YM and TM are higher than DM, and the lowest is ZM. Dry matter accumulation of lower, middle and upper of double cropping cotton were lower than that of DM, nitrogen application significantly increased the dry matter accumulation of lower, middle and upper of different planting patterns of cotton plant. The lint yield of double cropping cotton are lower than DM, and the lowest is ZM. The lint yield of cotton of different planting patterns reached the highest under N300. Double cropping cotton significantly increased the contribution for cotton yield of lower fruiting branch, reduced it of the upper fruiting branch. The contribution for cotton yield of lower fruiting branch of different planting patterns under NO treatment is greater than nitrogen application. The lint yield of lower, middle and upper of double cropping cotton are lower than that of DM, and the lint yield of upper of cotton have the most significant reduce.2 Effects of cropping system and N rate on uptake and utilization of N, P and K of cottonCompared with DM, double cropping cotton decrease the nutrient accumulation eigenvalues of different fruiting branches of cotton notably and the uptake percentages of nutrient of top of cotton in different degree. Nitrogen application improve the accumulation of nutrient of this four planting patterns, the rate of accumulation and the percentages of nutrient accumulation of the top of cotton. The nutrient use efficiency of cotton of the two varieties of YM is the highest and the ZM is the lowest, which reduce with the increase of n application rate. ZM reduce the nutrient use efficiency of upper fruiting branch of cotton. The nutrient use efficiency of upper fruiting branch of cotton influence the whole plant most.3 Effects of cropping system and N rate on the uptake percentages of nutrient and the relationship between nutrient accumulation and lint yield of cottonCompared with DM, Double-cropping cotton decreased the accumulation of N, P and K of cotton in different degree, and YM is the lowest.The N, P and K accumulation of the four cropping system of cotton increase with the N application rate’s improvement, N450 occupies first place, N300 comes second, and NO is the lest. Cotton on uptake percentages of P and K increased by DM、TM、YM、ZM. With the improvement of N’s application, the uptake percentages of P and K decrease gradually.The relationship between the accumulation of N, P and K of this Four planting patterns and the lint yield is quadratic curve, which first rises then falls. Compared with DM, TM,YM and ZM need higher nutrient accumulation amount in order to obtain high yield. The potential yield of TM and YM is greater than the DM.and the potential yield of ZM is the lowest. The utilization efficiency of N, P and K of ZM is also the lowest.