| Purposes:The oasis of one belt,one road in Manasi,is the main cotton producing area in the northern part of Xinjiang.It occupies an important position in the economy of the northern slope of Tianshan Mountain,and is also the main economic zone along the belt.However,in the past 20 years,the evapotranspiration characteristics and rules of drip irrigation under mulch in the oasis of Mahe River basin are not clear,and the best water demand model and irrigation system of drip irrigation under mulch are not clear.Therefore,this paper studies the influence of different drip irrigation conditions on the evapotranspiration process of oasis cotton field,and analyzes the water demand law under different irrigation quotas,determines the evapotranspiration process and water demand law of oasis cotton field,and formulates scientific irrigation system.Approaches:In this paper,the field experiment was carried out in Shihezi University water-saving irrigation experimental station.The data of lysimeter,crop growth and meteorology under different drip irrigation conditions were monitored,and the evapotranspiration process and law of cotton field under film drip irrigation oasis were analyzed.The evapotranspiration of different scales of cotton field was accurately monitored by photosynthesis instrument and EM50,and the model of farmland scale evapotranspiration was established In order to determine the water requirement law of cotton,the crop water requirement under different irrigation quota was used.Results:?1?Under the two different drip irrigation conditions,the evapotranspiration and the typical daily change trend are consistent,showing a single peak parabola pattern of low at both ends and high in the middle.Under the condition of mulching drip irrigation,the evapotranspiration decreased 93.31 mm,the evapotranspiration intensity decreased 0.56 mm/d and the water saving was 15%.Mulching can advance the growth period of cotton,accelerate the early growth of cotton,improve the soil moisture content and soil temperature,and provide favorable water and heat conditions for the emergence and early growth of cotton.The condition of mulching drip irrigation was beneficial to plant growth and material accumulation,increased boll number and weight per plant,and increased yield by 21.3%.?2?From plant scale to farmland scale,the scale-up model was studied.Firstly,the correlation between plant scale emission and leaf area was established,and the plant scale emission model of cotton covered with film was:T=1.18×10-4A+0.02.Then,the dynamic correlation between leaf area and stem diameter in different growth stages was analyzed,and the scale-up model of cotton covered with film was:Tsf=1.18×10-4Atotal+0.02.The results of quantitative division of evapotranspiration components under different mulching conditions showed that the plant emission under mulching conditions was always greater than that under no mulching conditions in the whole growth period,while the soil evaporation was always less than that under no mulching conditions,which indicated that mulching promoted the growth of plant leaf area and inhibited the soil evaporation.?3?The crop coefficient of drip irrigation without mulching was higher than that of drip irrigation without mulching.With the growth of plants,the slope and correlation coefficient of crop coefficient correlation formula are higher and higher,indicating that the effect of mulching on crop coefficient is smaller and smaller.The slope of correlation formula of crop coefficient in seedling stage is 0.5616,that in bud stage is 0.7796,that in boll stage is 0.8982 and that in boll stage is 0.8994.When irrigation quota is 4200 m3/hm2,cotton growth index and yield are the highest.The average water demand is 527.85 mm,52.82 mm in seedling stage,87.62 mm in bud stage,280.34 mm in boll stage and 107.07 mm in boll stage.Conclusion:During the whole growth period of drip irrigation under mulch,93.11 mm water was saved,15%water was saved and 21.3%yield was increased.The scale emission model of mulched farmland is:Tsf=1.18×10-4Atotal+0.02,which has a good scale-up effect.The optimal irrigation quota is 4200 m3/hm2,irrigation 12 times.Water demand in seedling stage is 52.82 mm,irrigation quota is 450 m3/hm3,water demand in bud stage is 87.62 mm,irrigation quota is 300 m3/hm2,irrigation cycle is 10 days,water demand in flower and boll stage is 280.34 mm,irrigation quota is 375 m3/hm2,irrigation cycle is 7 days,water demand in boll stage is 107.07 mm,irrigation quota is 225 m3/hm2. |
PDF Full Text Request