Effect Of Water And Nitrogen Regulation On Growth And Development Of Mechanized Cotton And Water And Nitrogen Utilization Efficiency

With the development of agricultural modernization,mechanized cotton planting mode has been widely used in Xinjiang.In order to find out the effect of different water and nitrogen regulation on the growth and development of mechanized cotton and water and nitrogen utilization efficiency,three kinds of pipe laying quantity(G5:laying five drip irrigation belts,G3:laying three drip irrigation belts,G2:laying two drip irrigation belts)and four nitrogen application levels were set in this experiment,which were N0:no nitrogen application(0 kg/hm~2),N1:0.75 times of the optimized nitrogen application(237.75 kg/hm~2),N2:317 kg/hm~2),N3:1.25 times(396.25 kg/hm~2)of the optimized nitrogen application amount.The split area experiment design was carried out to study the influence of different water and nitrogen control on the growth and development of mechanized cotton and water and nitrogen utilization efficiency in South Xinjiang.The main conclusions are as follows:1.In the early growth stage of machine picked cotton,different water and nitrogen treatments had no significant effect on agronomic characters.With the advance of growth period,the higher agronomic traits indexes of mechanical harvesting cotton increased with the increase of the number of pipe laying under the same fertilization level;at the same level of pipe laying,the agronomic traits of machine picked cotton increased first and then decreased with the increase of nitrogen application rate.Under G5 and G3conditions,the effect of Nitrogen Application on the plant height,the number of main stem leaves and other agronomic characters of mechanically harvested cotton was better than that of G2,the overall performance is G5>G3>G2,under G5 condition,the height of the beginning node of each branch was more than 18 cm,meet the requirements of mechanical cotton picking.therefore,increasing the number of pipes can optimize the agronomic characteristics of mechanized cotton picking.2.The accumulation of dry matter in the upper part of the ground increased with the development of cotton growing.there was no significant effect on dry matter accumulation and distribution of mechanized cotton under different water and nitrogen treatments in early growth stage.In the boll stage,the dry matter accumulation increased with the increase of the number of tubes and nitrogen application,there was no significant difference in dry matter ratio of vegetative organs and reproductive organs under different water and nitrogen treatments.In the early days of gagging,at the same nitrogen application level,the accumulation of dry matter in the upper part of the ground increased with the increase of the number of pipes,there is a maximum value under G5N2 treatment,85.97 g/plant.At the same level of pipe laying,the dry matter accumulation in the aboveground part of mechanized cotton increased first and then decreased with the increase of nitrogen application,which showed that N2>N3>N1>N0,too high or too low nitrogen application was not conducive to dry matter accumulation in vegetative organs of mechanized cotton.Under average nitrogen application,increasing the number of tubes can promote the dry matter accumulation of reproductive organs.3.The accumulation and distribution of nitrogen in cotton under different water and nitrogen treatments were different.At the flowering and Bolling stage,the nitrogen accumulation of mechanically harvested cotton increased with the increase of nitrogen application;under the same nitrogen application level,there was no significant difference in the nitrogen accumulation of mechanized cotton under different tube arrangement treatments.At the initial stage of Bolling,under the same pipe laying level,the nitrogen accumulation of cotton increased first and then decreased with the increase of nitrogen application,and the maximum nitrogen absorption was 363.17 kg/hm~2 when the nitrogen application was 317 kg/hm~2;under the same level of nitrogen application,there was a significant difference in nitrogen accumulation of mechanically harvested cotton under different pipe laying conditions,which was shown as G5>G3>G2.Under the G5 and G3 levels,the nitrogen accumulation of mechanically harvested cotton was significantly higher than that of G2 level from the boll stage to the initial stage of Bolling.The proportion of nitrogen accumulation in the reproductive organs of mechanically harvested cotton increased first and then decreased with the increase of nitrogen application,and increased with the increase of the number of tubes.The results showed that increasing the number of pipes and the appropriate amount of nitrogen application could ensure the sufficient supply of water and nitrogen in the later growth period,increase the accumulation of nitrogen in mechanically harvested cotton,and promote the absorption of nitrogen by cotton bolls.4.At the same level of pipe laying,the yield and its components of mechanized cotton increased first and then decreased with the increase of nitrogen application,which showed that N2>N3>N1>N0,with the maximum yield at 317 kg/hm~2.At the same level of pipe laying,the yield and its components of mechanized cotton increased with the increase of the number of pipe laying,and the yield of G5N2 and G3N2 was higher,6545.47kg/hm~2 and 6498.65 kg/hm~2,respectively,significantly higher than that of G2.The results show that increasing the number of pipes can increase the cotton production.Different water and nitrogen treatments had no significant effect on lint percentage.5.Under different water and nitrogen treatment,the content of soil nitrate nitrogen in the whole growth period of mechanized cotton has different degrees of change.The content of soil nitrate decreased first and then increased with the advance of growth process,and increased with the increase of nitrogen application.Under the same nitrogen application level,the content of soil nitrate nitrogen in 0-40 cm soil layer is G5>G3>G2,and that in 40-60 cm soil layer is G2>G3>G5.The results showed that increasing the number of pipes could increase the content of nitrate and decrease the loss of deep leaching.6.Under the same pipe arrangement level,the water use efficiency and the apparent nitrogen use efficiency first increased and then decreased with the increase of nitrogen application,there was a maximum value at 317 kg/hm~2 nitrogen application level.Too high or too low nitrogen application rate would reduce water use efficiency and apparent nitrogen use efficiency of machine picked cotton;nitrogen absorption efficiency,agronomic utilization efficiency and partial productivity of nitrogen decreased with the increase of nitrogen application.Under the same nitrogen application level,the agronomic utilization rate,nitrogen absorption efficiency,apparent utilization rate and partial productivity of nitrogen fertilizer were G5>G3>G2.The results show that the utilization efficiency of water and nitrogen can be improved by increasing the number of pipes.Based on the above conclusions,the nitrate nitrogen content of 0-40 cm soil layer can be increased by5 drip irrigation belts and 3 drip irrigation arrangements,in order to improve the water and nitrogen supply more sufficient and even in the middle and late growth period of machine picked cotton,so as to increase the dry matter accumulation,balance the proportion of reproductive organs and vegetative organs,and increase the nitrogen absorption of plants,to achieve the goal of high yield,and has a higher efficiency of water and nitrogen use.There was no significant difference in the final output of mechanical cotton picking under the arrangement of 5 drip irrigation belts and 3 drip irrigation belts,considering the input of drip belt cost,therefore,the machine picking cotton planting mode with one film and three drip irrigation belts is selected,The combined application of nitrogen fertilizer was 317 kg/hm~2,and increase irrigation frequency appropriately,it can obtain higher economic benefits.