Effects Of Irrigation Treatment On Soil Water And Salt Distribution And WUE In Cotton Root Zone Under Mulch Drip Irrigation

At present,the shortage of water resources and soil salinization have become the two major factors limiting the high quality,high yield and sustainable development of cotton in southern Xinjiang.How to achieve the goal of water-saving and salt control,high quality and high yield of cotton by making a scientific combination of irrigation technical parameters and irrigation schedule has become a research hotspot in related fields.In order to explore the effects of drip irrigation parameters on cotton growth,yield and water use efficiency in southern Xinjiang,the response process of cotton plant growth,seed cotton yield and quality index to soil water and salt in root zone under drip irrigation was studied,and the effects of different irrigation parameters and irrigation systems on soil water and salt distribution in saline alkali cotton field were analyzed,Based on the analysis of control test data and theoretical analysis,the main conclusions are as follows:（1）Under the condition of drip irrigation,the soil wetting body after irrigation is ellipsoid,and the range of wetting body increases with the increase of irrigation quota.When the emitter flow rate was 2.8L·h^-1and irrigation quota was 22.5 mm,the radius of soil surface moist area was the smallest（30.8 cm）;When the emitter flow rate was 5.6 L·h^-1and irrigation quota was 52.5 mm,the radius of soil surface moist area was the largest（50.7 cm）.When the irrigation quota is the same,the small emitter flow is conducive to the vertical infiltration of irrigation water;Under the condition of the same emitter flow,the infiltration depth of irrigation water increases with the increase of irrigation quota.With the increase of irrigation quota（22.5-52.5 mm）,the desalination effect of surface soil was more obvious.The treatment of 2.8 L·h^-1emitter flow and 52.5 mm irrigation quota effectively increased soil water storage in 0-60 cm soil layer,and significantly reduced soil salt content in 0-40 cm soil layer.（2）Compared with the pattern of 1 film with 2 strips and 6 rows,the pattern of one film with three strips and six rows is more conducive to the uniform distribution of irrigation water in the horizontal direction of the film,but the vertical infiltration depth becomes shallower,and the soil salt content in0-40 cm soil layer in the root zone is significantly lower;However,the boll weight per plant and boll number per plant decreased significantly,and the seed cotton yield increased by 362.10 kg·hm^-2and219.30 kg·hm^-2,respectively;Water use efficiency increased by 6.7%and 2.9%respectively.（3）The results showed that the increase of irrigation quota in growth period was beneficial to the decrease of soil salt content in cotton root zone,and the irrigation quota in growth period was 405 mm（the irrigation cycle in bud stage and flowering and boll stage was 10 d and 7 d respectively,and the irrigation quota was 45 mm）,which could provide a suitable soil water and salt environment for the normal growth of cotton.The plant height of cotton began to increase rapidly about 48 days after sowing,and reached the maximum value（75.0-89.0 cm）at 94 days after sowing.The total leaf area of cotton per plant increased first and then decreased with the increase of irrigation amount.With the increase of total irrigation amount（390-457.5 mm）,the aboveground biomass of cotton first increased and then decreased.The treatment with 405 mm irrigation quota had the highest seed cotton yield(6641.18 kg·hm^-2),but water consumption（447.77 mm）was not the highest,and water use efficiency(1.45 kg·m^-3)was the highest;The cotton fiber quality indexes such as lint percentage（40.74%）,average length of upper half（31.27 mm）,evenness index（86.93%）,specific breaking strength(27.37c N·tex^-1)and elongation（6.77%）were the best among all treatments,which were conducive to high quality and high yield of cotton.Considering seed cotton yield,cotton fiber quality and WUE,the irrigation mode of 405 mm in growth period（sowing with enough moisture,no irrigation in seedling stage,10 d and 7 d in bud stage and flowering and boll stage,45 mm in irrigation quota）was the most suitable water management mode in cotton field.