Effects Of Plastic Film Mulching On Water Transformation And Utilization Efficiency Of Summer Maize

Maize is the most important crop in China,which is limited in dry farming,because of the dependence on moisture and temperature.Plastic film mulching,which can raise the temperature and keep the moisture,restrain soil evaporation,improve soil fertility and increase yield and WUE,is widely used to improve maize yield and WUE in dry farming.Although the effect of plastic film mulching on water saving and yield increasing has been confirmed by lots of studies by experts and scholars at home and abroad,and has been widely recognized,there are few studies on the dynamic process of water transformation including input,migration and output of farmland ecosystem under plastic film mulching,and the water use efficiency of each link of farmland water transformation under plastic film mulching needs to be studied.Therefore,Summer Maize without irrigation in Guanzhong plain was used to explore the effect of plastic film mulching on farmland water transformation process and utilization efficiency of summer maize in this study.We carry out this experiment in Yangling,Shaanxi Province from 2019 to 2020,and it was with three treatments of full film mulching（FM）,half film mulching（HM）and traditional tillage（CK）.Based on the observation of soil profile moisture,surface soil temperature,growth and development index,evaporation,transpiration,yield and water use efficiency under different treatments,the comprehensive effect of plastic film mulching on water transformation process of Summer Maize Farmland ecosystem was expounded.The results are as follows.（1）Plastic film mulching increases the surface soil temperature and retains soil moisture.The water content of 0～120 cm soil profile was increased by film mulching,especially in summer maize,s early stage.The average profile water content of summer maize under FM and HM increased by 6.05%and 3.22%respectively.Film mulching increased the surface soil temperature of 0～10 cm,especially in summer maize,s early stage.The accumulated effective temperature of summer maize under FM and HM increased by 16.46%and 6.13%respectively in two years.（2）Plastic film mulching significantly inhibited the evaporation among summer maize trees and reduced the ineffective water consumption during the growth period.The evaporation of summer maize under FM and HM decreased by 51.05%and 30.65%respectively in two years.Because mulching has changed the surface morphology,the micro lysimeter method for measuring evaporation should also be innovated.The traditional method of"LB*HR"is suitable for HM.However,the measurement method of"LM"is more accurate.under FM.（3）Plastic film mulching significantly increased the transpiration water consumption of summer maize,and changed the water consumption structure of Summer Maize in growth period.The total transpiration water consumption of FM and HM increased by 35.5%and19.0%respectively in two years.In addition to the influence of plastic film and summer maize,the transpiration of summer maize is also closely related to meteorological factors.The stem flow rate of summer maize had a significant positive correlation with solar radiation,pressure deficit,atmospheric temperature and wind speed,and a significant negative correlation with relative humidity,with correlation coefficients above 0.5.（4）Plastic film mulching promoted the growth of summer maize shoot.The plant height,leaf area index and aboveground biomass increased by 4.8%and 1.6%,15.41%and 11.07%,10.58%and 6.37%respectively.At the same time,plastic film mulching optimized the grain filling process of summer maize,increased the filling rate of each stage of summer maize filling period,optimized the grain filling process,and increased the grain yield of summer maize after the end of final filling.The average grain filling rate under FM and HM increased by 15.00%and 6.91%,respectively.The grain yield under FM and HM increased by 27.90%and 17.39%in two years.（5）Plastic film mulching improved water use efficiency of summer maize field.WUE_TWIunder FM and HM increased by 33.97%and 23.60%respectively,and WUE_ETunder FM and HM increased by 33.90%and 19.78%respectively.Plastic film mulching can change water consumption structure and increase T/ET of summer maize during growth period by inhibiting evaporation and promoting plant transpiration to increase WUE_TWI.