| Given the severe seasonal drought and uneven spatial and temporal distribution of moisture and temperature in subtropical hilly areas in China,kiwifruit yield and quality are under the double stress of soil moisture deficit and high temperature in summer.It is of great significance to study the effects of soil mulching treatment on adjusting soil moisture and temperature environment in kiwifruit orchards.In this thesis,soil column test and field observation test were combined to study the influence of five mulching treatments(weed proof cloth+white film(F+B),weed proof cloth film(F),black film(H),white film(B),and straw mulching(J))on soil moisture and temperature.In addition,non-mulching treatment(CK)was also applied as a blank controller to analyze the correlations between different group settings.At last,HYDRUS-1D was used to simulate the variations of soil moisture and temperature under mulching conditions,and the numerical model was evaluated by five indexes.The main conclusions were obtained as follows.(1)The effect of the mulching treatments taken on the surface of the soil column on soil moisture evaporation was analyzed,and the moisture retention and temperature regulation effects of each treatment were compared.Under the continuing point light source,soil evaporation was reduced by 47.05%～55.20%in the mulching treatments compared with CK.Soil moisture retention under mulching conditions were in the order of F+B,F,J,B,H,CK.The soil temperature and temperature differences between soil layers showed a decreasing trend with increasing soil layer depth.Compared with CK,soil temperature increased by2.43°C in the F+B treatment and decreased by 3.46°C and 4.85°C in the F and J treatments,respectively.(2)The effects of mulching treatments adopted in the field site on soil moisture and temperature were studied to validate the findings in the soil column test.In this test,mulching treatments were adopted to improve the soil moisture and temperature for kiwifruit growth.Compared with CK,the mulching treatments reduced soil evaporation by 27.67%%～81.05%and increased soil moisture content by 7.62%～53.33%.The mulching treatments were beneficial in reducing the daily soil evaporation by 53.26%and 57.85%on sunny and cloudy days,respectively.Compared with CK,soil temperature increased by 0.90°C in the F+B treatment and decreased by 2.75°C and 4.84°C in the F and J treatments in summer.Similarly,the mulching treatments reduced daily variation in soil temperature by 34.04%and 26.47%on sunny and cloudy days,respectively.(3)The characteristics of changes in field weeds,kiwifruit yield and quality under different mulching conditions were studied to reveal the correlations between soil properties(soil moisture and temperature)and kiwifruit growth(yield and quality).Compared with CK,the ability to control weeds was improved by 87.42%in the B and J treatments.F+B,F,and H treatments have good weeding effect.In addition,the yield and quality of kiwifruit increased significantly(p<0.05)under the F treatment,increasing by 3.45%,3.9%,and18.7%in kiwifruit yield per fruit tree,fruit weight per kiwifruit,and sugar to acid ratio,respectively.Soil moisture was positively correlated with kiwifruit weight(R~2>0.807*),while soil temperature was negatively correlated with dry matter quality of kiwifruit(R~2>0.794*).(4)A model on soil moisture and temperature variation in kiwifruit orchards in subtropical hilly areas in China was established based on HYDRUS-1D,and the reliability of the model was tested.The numerical model can accurately simulate the processes of soil moisture and temperature variation in kiwifruit orchards under different mulching treatments,and the accuracy of each test index was high,where the coefficient of R~2>0.65,the NSE>0.5,and the RMSE tended to be close to 1.In summary,the F treatment can significantly improve soil moisture retention capacity and reduce soil temperature,thus,alleviating the effects of seasonal drought and high temperature stresses on kiwifruit yield and quality.What’s more,F treatment shows an excellent ability to control weeds in the field,making it a more suitable mulching material for kiwifruit orchards in subtropical hilly areas in China. |
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