Response Of Wheat Growth And Development Characteristics And Soil Microbial Community Diversity To Limited Irrigation

Water is one of the main factors restricting wheat production in the Hebei Plain.The irrigation water used for intensive wheat production is mainly groundwater.Excessive extraction of groundwater for irrigation has caused the groundwater level to decrease year by year.In order to maintain high yields and sustainable use of groundwater,Analyzing the water consumption characteristics and microbial community characteristics of wheat in different limited irrigation treatment,provides scientific decision-making basis for improving the water use efficiency in this area.This study was conducted in Lizhuang Village,Fourth Tuan Town,Quzhou County,Handan City,Hebei Province(36°86’ N,115°02’ E,average elevation 39.6 m)from 2018 to 2020.Two wheat varieties Jimai 22(J22)and Shinong 086(S086)were selected.On the basis of 90 mm irrigation before winter,three treatments were set:no irrigation after overwintering period(W0),irrigation at the jointing stage(W1,75 mm),irrigation at the jointing+flowering stage(W2,75 mm+75 mm).The growth and development dynamics,soil water consumption,nitrogen content,changes in enzyme activities and the diversity of microbial difference of two wheat varieties under different water treatments were systematically analyzed.The main findings are as follows:1.Effect of limited irrigation on growth and development and yield of wheatIn the two growing season,W2 treatment can cope with the accumulation of active oxygen in the cells and delay the senescence damage of the flag leaves through the accumulation of protective enzyme activities and the improvement of osmotic adjustment ability in flag leaves after anthesis.The post-flowering wheat leaf area index(LAI)was the highest in treatment W2,followed by W1,and W0 was the lowest.The dry matter accumulation of W1 and W2 during flowering and maturity was significantly higher than that of W0,and W2 treatment was higher than W1;W2 was beneficial to dry matter accumulation after flowering and had a higher contribution rate to the grain.In the two growing seasons,the differences in the yields of W1 and W2 were not significant.In 2018-2019,the yields of W1 and W2 were 7803.26 kg·hm-2,8188.61 kg.hm-2(S086)and 7773.67 kg·hm-2,8110.62 kg·hm-2(322),respectively.In 2019-2020,the yields of W1 and W2 were 8182.29 kg·hm-2,8286.04 kg·hm-2(S086)and 8064.46 kg·hm-2,8122.30 kg·hm-2(J22),respectively.2.Effect of limited irrigation on soil water consumption and water use efficiencyIn the two growing seasons,the post-flowering water consumption and water consumption intensity of S086 and J22 increased with the increase of irrigation frequency.The water consumption,daily water consumption and water consumption modulus of W2 treatment from grouting to maturity were significantly higher than those of W1 and WO treatments.In 2018-2019,the total water consumption of W1 is significantly higher than that of W2 by 16.68%(S086)and 19.23%(J22).The total water consumption of W1 in 2019-2020 is significantly higher than that of W2,which is 7.52%(S086)and 10.16%(J22)higher,respectively,but there is no significant difference in water use efficiency between W1 and W2 in the two growing seasons.In 2018-2019,the water use efficiencies of S086 and J22 are 11.08%and 14.27%higher than that of W2,respectively.In 2019-2020,the water use efficiency of S086 and J22 are W1 W2 increased by 6.11%and 9.37%respectively.3.Effect of limited irrigation on plant nitrogen accumulation and distributionIn 2018-2020,the nitrogen accumulation in mature stage grainsof the two varieties,the transfer amount of vegetative organs to the grain before anthesis,and the amount of nitrogen accumulation in the grain after anthesis were all W2 higher than W1,but the difference was not significant.In 2018-2019,the nitrogen absorption efficiency W2 was significantly higher than that of W1,11.11%(S086)and 7.22%(J22)higher,respectively,and the nitrogen fertilizer production efficiency W2 increased by 5.06%(S086)and 4.32%(J22),respectively,compared with W1.In 2019-2020,the nitrogen absorption efficiency W2 was significantly increased by 10.91%(S086)and 7.56%(J22)compared with W1,and the nitrogen fertilizer production efficiency W2 was increased by 1.28%and 0.73%,respectively,compared with W1 treatment.It showed that W2 treatment can promote the accumulation of nitrogen in wheat after anthesis,accelerate the transfer of nitrogen from vegetative organs to the grain before anthesis,promote the accumulation of nitrogen in the grain after anthesis,and facilitate the absorption of nitrogen by wheat.4.Effect of limited irrigation on NO3--N,NH4+-N and soil enzyme activityThe content of NO3--N in soil W0 treatment was higher than that of W1 and W2 in the soil layers of 0-60 cm during wheat growth period,and NH4+-N content was higher than WO treatment in W1 and W2 treatment.W0 can significantly increase the activity of urease;soil alkaline phosphatase activity in the jointing stage,filling stage and maturity stage were the highest in W2,and W0 was the lowest.The alkaline phosphatase activity of W2 treatment in the filling stage and maturity stage was significantly higher than that of W1.The sucrase activity was the highest in both the jointing stage and the filling stage,followed by W2,and W0 was the lowest,and W1 was significantly higher than W0.5.Effect of limited irrigation on the diversity of soil microbial communityTreatments W1 and W2 can significantly increase the soil rhizosphere bacterial and fungal community diversity.As the amount of irrigation increases,Actinobacteria and Basidiomycota decreased relative abundance,and the abundance of Chloroflexi and Ascomycota increased.Spearman correlation analysis also proved that Nocardioides,Promicromonospora,Filobasidium,Alternaria and Gibberella were significantly positively correlated with soil water content,NO3--N,sucrase,and alkaline phosphatase,and extremely significantly negatively correlated with nitrate nitrogen and urease.In summary,soil water content,NO3--N,urease,sucrase,and alkaline phosphatase were the main environmental factors driving changes in soil microbial communities under different irrigation amounts.Spring irrigation(W2 and W1)interacte with soil environmental factors to improve the living environment of the microbial flora,promote the secretion of nutrients in the rhizosphere,provide suitable water and nutrients for the growth of the above-ground wheat,ensure the nitrogen and phosphorus required for the normal growth of the leaves after anthesis,increase the dry matter accumulation and the grain nitrogen content after anthesis,thereby increasing the grain yield and water use efficiency.In wheat production and cultivation,especially in the Hebei Plain with high water demand,during the critical period of wheat water demand,according to different annual precipitation and combined with soil moisture dynamics,limited irrigation is carried out during jointing or jointing and flowering periods can obtain higher yield and water use efficiency.