Response Of Pear Growth To Soil Hydrothermal Under Rainfed Rainfall

Dry farming mulching cultivation technology is a widely used orchard management measure,which has obvious promotion effect on water use and fruit tree growth.At present,there have been a large number of related researches on dry farming mulching technology,but most of the research is focused on apple orchards,and research on covering treatment of pear orchards is relatively rare.In order to study the response of pear tree growth characteristics to soil water and heat under the conditions of rain cover and rain collection,this paper uses a combination of field experiments and theoretical analysis to study the soil water and heat distribution characteristics,pear tree physiological growth,and yield and quality indicators of pear orchard under different mulching treatments(T1: yearround ground cover,T2: April-September ground cover,T3: October-March the following year,ground cover,T4: straw cover,CK: control group without cover).The main conclusions are as follows:(1)The soil water and heat distribution rules of all treatments under dry farming conditions are consistent as a whole.It can be seen from the specific comparison of the five treatments that the covering treatment can keep the soil moisture at a high level,reduce the daily change of soil temperature,and have good thermal insulation for the soil.Among them,the overall water retention effect of straw mulch treatment(T4)is the best.Compared with the control group,the average soil moisture content can be increased by about 6.89%,and its thermal insulation effect is also the best.It can increase the soil temperature by about 5.17℃ during the overwintering period of fruit trees In the midsummer period,the soil temperature can be reduced by about 2.56℃.The ground cover treatment(T1)throughout the year due to the setting of rain gullies on both sides of the tree row has a significant replenishment effect on the soil moisture in the middle and deep layers.The rainfall collection effect after rain is also significantly better than other treatments,and the precipitation utilization rate can basically be achieved 48.69%.(2)Compared with the non-covering treatment of the control group,each mulching treatment under drought conditions can significantly increase the leaf water potential and chlorophyll content of the leaves.The leaf water potential and the average chlorophyll value of each treatment during the whole growth period are T4>T1>T2>T3>CK.In addition,each mulch treatment can obviously promote the growth and development of the new shoots and trunk diameter of pear trees.Among them,the cumulative growth of the new shoots and trunk diameter of straw mulch treatment is the largest,which is 25.12% and 15.49% higher than the control group respectively.(3)Compared with the non-covering treatment in the control group,each covering treatment under dry farming conditions can significantly increase the yield of Yuluxiang pear and improve the quality of pulp.Among them,the single fruit weight,pulp hardness and soluble solids content of the fruit covered with ground cloth throughout the year were the largest,which were 12.74%,8.10% and 10.03% higher than the control group;the fruit shape index value of the fruit covered with straw was the largest(0.92),the acidity value is the smallest(0.36%),which is 21.74% lower than that of the control group.(4)Construct an evaluation system based on the previous analysis,combined with principal component analysis,a total of three principal component factors were extracted,and the cumulative variance contribution rate reached 84.276%.The first principal component F1 is characterized as the main component of pear tree growth,and the F1 score of each treatment is T4>T1>T2>T3>CK;the second principal component F2 is characterized as the quality main component of Yuluxiang pear,and the F2 score of each treatment is T1>T4>T2>T3>CK;the third principal component F3 is characterized as the main component of the physiological status of pear trees.The F3 score ranking of each treatment is T4>T1>T2> T3>CK;the comprehensive principal component(F)score ranking is T4> T1>T2>T3>CK,which shows that under the conditions of dry farming and rain collection,comprehensively considering the growth index,quality index and physiological status of pear trees,the most suitable covering method for the threeyear-old Yuluxiang pear in this experimental area is straw covering(T4).