Research On The Effect Of Water-fertilizer Coupling On The Growth And Yield Of Machine-picked Cotton

Xinjiang has a long history of cotton planting and is the largest cotton production base in China.With the development of mechanization and intensification,machine-picked cotton planting has been widely promoted.Taking cotton as the research object,the pit test was carried out.Three drip irrigation volumes?W1:2160m³/hm²?W2:2880 m³/hm²?W3:3600 m³/hm²?and three fertilization rates?F1:150-60-30?F2:250-100-50?F3:350-140-70kg/hm²,N-P₂O₅-K₂O ratio as 1:0.4:0.2?were set up to conduct the orthogonal coupling experiment.The effects of different irrigation and fertilization treatments on the growth and yield of mechanically harvested cotton were analyzed.The main conclusions were made as following:?1?Under different fertilization levels,plant height,stem diameter and leaf area of cotton harvested by different treatments increased with the increase of irrigation.At the same irrigation level,with the increase of fertilizer application,the cotton plant height,stem diameter and the total number of cotton bolls increased at first and then decreased,appropriate fertilization contributed to the increase of cotton plant height and stem,but over a certain level,fertilization inhibited plant height and stem,cotton growth was under water stress under irrigation?W1?,at the same fertilization level,irrigation affected plant height and stem,the sound is W3>W2>W1.From the point of view of different drip irrigation and fertilization treatments,the plant height and stem of F2W3 combination were the largest,and the W1F3 treatment was the smallest.The same plant height and stem are similar,the effect of irrigation on leaf area index was W3>W2>W1 at the same fertilization level.With the increase of fertilization amount,the leaf area index increased first and then decreased.W2F2,W2F3 and W3F2 treatments were better in terms of different water and fertilizer treatments,which were 3.6,3.8 and 3.7 respectively,and accorded with the leaf area index of high-yield cotton.?2?With the advance of growth period,the dry matter accumulation of cotton increased rapidly and reached its peak in August.The change rule of dry matter accumulation in cotton showed"S"type change on the whole;Under the same irrigation level,the dry matter content of cotton shoots increased with the increase of fertilizer application,the dry matter content of cotton roots at fertilization level F2 and F3 was significantly higher than that of F1,the dry matter content of cotton roots increased first and then decreased with the increase of fertilizer application,and reached the maximum value at fertilization level F2.Among them,the dry matter content of cotton roots treated with F2W2 water fertilizer was the largest,which was4.7g/plant.Effective boll number and 100-boll quality of cotton increased with the increase of fertilizer application under low irrigation level?W1?and medium irrigation level?W2?;Under higher irrigation level?W3?,the number of effective bolls of cotton increased first and then decreased with the increase of fertilizer application,but there was no significant difference in the quality of 100 bolls under F2 and F3fertilization treatments;Under F1 fertilization treatment,100 bolls quality and effective bolls number increased with the increase of irrigation amount,under F2 and F3 fertilization treatment,100 bolls quality and effective bolls number of mechanically harvested cotton increased slowly with the increase of irrigation amount.?3?The root-shoot ratio of cotton decreased with the increase of fertilizer application under medium and high water irrigation.At the same irrigation level,the PFP showed a downward trend with the increase of fertilizer application.At the same fertilization level,the partial productivity of fertilizer increased slightly with the increase of irrigation water,at the fertilization level of F3,the difference of PFP between W2 and W3 treatments was small.At W1 and W2 irrigation levels,water use efficiency decreased with the increase of fertilizer application;at W3 irrigation level,water use efficiency increased first and then decreased with the increase of fertilizer application.The relationship between dry matter accumulation and water use efficiency of mechanically picked cotton showed a quadratic parabola,There is a linear relationship between the above-ground dry matter quality and seed cotton yield in mechanically picked cotton.Different water and nitrogen treatments have a certain impact on the yield of mechanically harvested cottonseed cotton.The positive and negative effects of irrigation amount are relatively obvious within the design level,while the positive effects of nitrogen application amount are obvious,and the negative effects are gentle.The order of effect of the two factors on seed cotton yield is:the amount of nitrogen fertilizer applied is greater than the amount of irrigation water,and there is synergistic effect between water and fertilizer.The best combination of all factors was:when the irrigation water?W?was320.5m³/hm² and the nitrogen fertilizer?N?was 292.6kg/hm²,the seed cotton yield was 6082.5 kg/hm².?4?At the same fertilization level,soil water content increased with the increase of irrigation.Soil nitrate nitrogen mainly concentrated in the depth of 0-40 cm,with the increase of soil depth,soil nitrate nitrogen content showed a downward trend,and most of the nitrate nitrogen in all levels of soil treatment concentrated between 0-15 cm.Under W1 irrigation level,the water content is insufficient and the fertilizer dissolves less,so nitrate nitrogen accumulates in the soil surface and migrates less downward.Under W2irrigation level,the fertilizer dissolved sufficiently,it is possible that the higher utilization rate of nitrate nitrogen under this irrigation amount leads to the lower nitrate nitrogen content in soil layer.Under W3irrigation level,sufficient water resulted in obvious downward movement of fertilizer,which led to the increase of nitrate nitrogen content in deep layer.W2F2 treatment soil nitrate nitrogen distribution depth40-80 cm,cotton roots mainly distributed in this range is conducive to the absorption of nutrients by cotton.