Effects Of Aerated Infiltration Irrigation On Soil Water And Salt Transport And Cotton Growth Physiology

Xinjiang is arid and rainless,agricultural water resources are scarce,and saline alkali land is widely distributed.Expanding new water-saving irrigation technology and saline alkali land improvement technology is of great significance to promote agricultural development and economic progress in Xinjiang.Aerated infiltration irrigation technology is the further development of efficient and water-saving underground irrigation technology.It can alleviate the damage of underground drip irrigation technology to soil structure,and promote the growth and development of crops by adjusting the physical and chemical properties of soil,so as to increase production and income.In order to explore the effects of aerated infiltration irrigation model on soil water and salt,cotton growth physiology and salt tolerance of Cotton Seedlings under the environment of high salt and water shortage in southern Xinjiang,three experiments were carried out in laboratory,field and greenhouse.(1)Indoor soil box infiltration test,set the test treatment as two factor and two-level test of 1 times of standard air volume,aerating before irrigation(T1),aerating in the middle section of irrigation(T2),1.5 times of standard air volume,aerating before irrigation(T3),and aerating in the middle section of irrigation(T4),and set the non aerated treatment CK as the control group,a total of 5 treatments.Standing for 24 hours after irrigation,analyze the infiltration rate of water in the soil and the spatial distribution of water and salt in the wetting body,and explore the effects of the two factors on the infiltration rate of water and the spatial distribution of water and salt.(2)A field experiment of eight treatments including irrigation quota(four irrigation gradients determined according to crop water demand coefficient and ET0)and aeration treatment(aerated and non aerated)was carried out to explore the effects of aeration and irrigation quota on the temporal and spatial distribution characteristics of soil water and salt in cotton field and cotton growth,biomass and root system configuration during the whole growth period of cotton.(3)Carry out the salt tolerance test of cotton seedlings in greenhouse,and set four gradients(600)? The effects of aeration on the physiological indexes of cotton seedling growth were explored and the effects of aeration on the salt tolerance of cotton seedlings were clarified.The main research results are as follows:(1)When the irrigation amount is fixed,the aeration treatment shortens the irrigation time.In the indoor test,the irrigation time of T1,T2,T3 and T4 treatment is shortened by 8.70%,28.99%,31.88% and 43.48% respectively compared with CK treatment,indicating that the water infiltration rate in soil is faster in aeration treatment than CK treatment,and the infiltration rate increases with the increase of aeration.The average mass moisture content of CK,T1,T2,T3 and T4 is 16.2%,13.31%,14.61%,13.07% and 13.21% respectively at a horizontal distance of 0 cm from the infiltration irrigation pipe and a one-dimensional depth of 20 ? 30 cm.At the horizontal distance of 15 cm from the infiltration irrigation pipe and the one-dimensional depth of 10 ? 35 cm,the average mass moisture content of soil is 5.68%,8.65%,8.72%,8.74% and9.49% respectively,which indicates that the moisture distribution in the moist body of aerated treatment is more uniform than that of CK treatment.The larger water diffusion range makes the desalting range of aerated treatment larger and the salt washing effect better.Under the same air volume treatment,the effect of aeration in the middle section of irrigation is better than that before irrigation.Through the fitting of different infiltration models,it is found that Kostiakov model and general empirical model are more suitable for underground infiltration irrigation mode of gas filling treatment before irrigation.(2)The temporal and spatial distribution of water and salt in soil is significantly affected by irrigation quota and aeration.In 0 ? 60 cm soil layer,increasing irrigation quota and aeration treatment can improve the diffusion range and desalination effect of water in soil.With the increase of irrigation quota,this lifting effect is more significant.Aerated irrigation of cotton increased plant height,stem diameter,leaf area and dry matter accumulation by 4.87%,6.28%,8.46% and 15.55%,root mass density,root length density and root volume by 15.04%,17.34%and 11.27%,yield by 10.53% and IWUE by 6.88%.This shows that aerated irrigation can effectively promote cotton growth and root development,and improve cotton yield and water use efficiency.(3)The salt tolerance test of greenhouse seedlings showed that under the same irrigation water conductivity,the daily increment of plant height,leaf area,stem diameter and SPAD value of cotton treated with aeration increased by 8.11%,12.56%,2.02% and 4.71% respectively,the fresh weight of stem,leaf and root increased by 10.61%,7.21% and 8.69% respectively,and the dry weight of stem,leaf and root increased by 10.83%,8.34% and 27.39% respectively,and the photosynthetic performance of cotton seedlings treated with aeration was stronger than that without aeration.The conductivity value of irrigation water has a significant effect on the growth and physiological indexes of cotton seedlings,and the conductivity value is 600 ?Compared with the other three irrigation conductivity values,the daily increment of plant height,leaf area and SPAD increased by 18.43%,21.57% and 12.13%,the fresh weight of stem,leaf and root increased by 19.67%,18.68% and 12.26% respectively,and the dry matter accumulation of stem,leaf and root increased by 25.32%,15.34% and 21.84% respectively.This shows that brackish water irrigation will have an inhibitory effect on the growth physiology of cotton seedlings,and this effect gradually increases with the increase of electrical conductivity.The aeration treatment can effectively reduce the inhibitory effect of brackish water irrigation on cotton seedlings,promote the growth of cotton seedlings and improve the salt tolerance of cotton at seedling stage.