Research On Water Requirement Regulation And Irrigation Scheduling Of Machine Picked Cotton In Arid Oasis Area

Xinjiang is located in the arid region of northwestern China,and has become the largest cotton plantation area of China with its unique natural environment and climatic conditions.With the improvement of industrial and agricultural level,the planting and harvesting of cotton also developed towards mechanization and intensification.The appearance of the machine picked cotton realized the cotton planting and harvesting mechanization,and got widespread application in Xinjiang.In order to adapt to the development of machine picked cotton,cotton planting,mulching methods had undergone great changes,under the traditional planting methods,the water requirement index,irrigation system was no longer suitable for mechanical planting.Thus,how to achieve high quality and efficient irrigation was the urgent problem which was the main for cotton production in this area.Therefore,test-pit experiments were set under different planting modes(M1,M2,CK)to study the influence of soil water,temperature and salt,and then the effect of irrigation lower limits on the characteristics of soil moisture dynamic variation,plant growth,and seed cotton yield as well as water use efficiency were investigated.Quality and efficient irrigation index of machine picked cotton was ensured preliminarily.The results showed that:(1)The effects of different planting patterns on soil water,salt and temperature were analyzed.In terms of water,in the early stage of growth,the change trend of soil moisture content was basically same,and the quality water content was hardly different.In the middle and later period of growth,there was a significant difference in soil moisture content.During the growth period of each soil layer under different planting patterns,soil water variation range was 8.58~20.20 %,the soil moisture content of the root zone during the blooming period didn't have reached the field holding water rate of 70 %,and had a water stress in different degree on cotton,water stress under M1 model was the largest.In terms of salt,the soil salt in the root layer of each planting pattern had a trend of first increased and then decreased,and increased in last period.In the soil layer of 0~100 cm,the soil salt had a trend of first decreased and then increased.In terms of temperature,three kinds of plastic film mulching cultivation mode had good effects on improving soil temperature and reducing the rate of temperature changes to maintain soil temperature.In conclusion,compared with the pattern of M1 and CK,the pattern of M2 was favorable.(2)Water requirement regulation of machine picked cotton under different irrigation treatment were analyzed.The whole growth period of 0~100 cm soil moisture fluctuated largely,along with the advance of growth stage soil moisture was first increased and then decreased,which reached a maximum in the flowering-boll stage.Through analysis of soil moisture of each layer,machine picked cotton moisture absorption in vertical direction mainly distributed in the soil layer of 0~60 cm.Water requirement and water requirement intensity of machine picked cotton in the whole growth period were dynamic variables.Under M1 mode,water requirement and water requirement intensity of machine picked cotton during the whole growth period were 616.81~685.42 mm and 1.20~8.24 mm/d,respectively.Under M2 mode,water requirement and water requirement intensity of cotton picked machine during the whole growth period were 534.61~599.09 mm and 1.06~6.82 mm/d,respectively.(3)The influence of different irrigation treatment on the height,stem diameter and leaf area of cotton plant was expounded.Under different irrigation treatments,the height increased with higher irrigation lower limits,the stem diameter increased with higher irrigation lower limits,the leaf area increases with higher irrigation lower limits.Under the same irrigation lower limit,M2 mode was better than M1 mode on plant height,plant diameter and leaf area.(4)The high quality and high efficiency irrigation index of drip irrigation cotton was initially determined.Irrigation lower limits in too high or too low level were detrimental to the improvement of production and water use efficiency,combined with the influence of yield,irrigation water use efficiency and water use efficiency under different irrigation treatment,and irrigation lower limit index in the arid area oasis was formulated.As for M1 mode,30 mm of irrigation water was applied to ensure emergence after sowing,the lower limit of soil moisture at the squaring stage water was 65 %,and the irrigation water quota was 24.5 mm,the lower limit of soil moisture at the flowering-boll stage water was 75 %,and the irrigation water quota was 30 mm,there was no water applied at the boll opening stage.As for M2 mode,30 mm of irrigation water was applied to ensure emergence after sowing,the lower limit of soil moisture at the squaring stage water was 60 %,and the irrigation water quota was 27.5 mm,the lower limit of soil moisture at the floweringboll stage water was 75 %,and the irrigation water quota was 30 mm,there was no water applied at the boll opening stage.