| As one of effective measures of non-project water-saving measures, mulching technology for moisture conservation has been attracted more and more attention. An experiment with summer maize as a tested material had been conducted in field and in the lysimeters under a rain shelter. The effect of plastic film mulching (PM), 10500 (SM1), 7500 (SM2), 4500 (SM3) and 1500 (SM4) kg·hm-2 of straw mulching quantity on soil temperature, water-consuming law, crop physiological characteristics, yield and water use efficiency of summer maize was conducted by adopting complete randomized experiment design and taking no mulching as control (CK), and the covering effects under different soil moisture conditions were analyzed. The irrigation schedule of water-saving and high efficiency for summer maize under different mulching measures were established.Through experimental study and theoretical analysis for two years, the preliminary research results were obtained as follows:(1) The maximum daily variation amplitude of soil temperature appeared a decline trend with the increase of soil depth, which expressed by an exponential function. The slope of the function in SM1 treatment was the maximum and that in PM treatment was the minimum. The maximum daily variation amplitudes of profile temperature from 8:00 to 20:00 increased first and then decreased with the prolongation of time, which could be fitted by a quadratic function.The maximum daily variation amplitudes of soil temperature decreased gradually with the increase of straw mulching quantity. There was a linear correlativity between soil temperature and air temperature in different treatments. The maximum rising rate of soil temperature with air temperature was PM treatment, the next was CK treatment, and the minimum rate was SM treatment. In addition, the size order of warming rate for four straw mulching quantities was SM4>SM3>SM2>SM1.(2) Straw and plastic film mulching exhibited a favorable water conserving function, which could effectively reduce soil water evaporation. The effects of soil moisture conservation for four straw mulching quantities increased gradually with straw mulching quantity. Taking high soil moisture content treatment for example, the inhibition rate of soil evaporation with straw mulching was from 34.07% to 63.51% and from 33.38% to 63.71% in two test cycle, respectively. The results in field trial showed that the water consumption of summer maize had changed in time and space after the application of straw mulching and plastic film mulching. The water consumption of summer maize in mulching treatments at the earlier growing stage was less than that in CK treatment, and the peak of water consumption in mulching treatments was in the middle growth stage. The water consumption of summer maize in PM and SM treatment in the whole growth period was less than that in CK treatment under different soil moisture conditions. The water consumption of summer maize in PM treatment was the minimum, and the water consumption of SM treatment decreased with straw mulching quantity increase gradually.(3) The straw and plastic film mulching had a promoting effect on several growth indexes (such as plant height, stem diameter, leaf area index, above-ground biomass, etc.) and physiological indexes (e.g. photosynthetic rate, stomatal conductance, etc.) under different soil moisture. There were certain yield-increasing effects for summer maize with surface mulching. Under different soil moisture treatments, the yield in SM1 treatment and CK treatment was the maximum and the minimum, respectively. The size order of yield in different treatments was SM1>PM>SM2>SM3>SM4>CK in the first test cycle, and SM1>SM2>PM>SM3>SM4>CK in the second test cycle.(4) The plastic film and straw mulching could improve water use efficiency of summer maize at different degree. The water use efficiency in plastic film and straw mulching treatments increased by from 1.47% to 36.17% than that in CK treatment under high soil moisture condition, by from 4.04% to 50.64% under middle soil moisture condition, and by from 4.75% to 40.39% under low soil moisture condition. Thus it showed that the contribution rate of mulching measures to increase water use efficiency under middle and low soil moisture condition was greater than that under high soil moisture condition.(5) Based on the comprehensive evaluation of the three indexes including water consumption, yield and water use efficiency, the PM, SM1and SM2 treatments under middle soil moisture condition could achieve good effect of water saving and increasing yield. Considering from the angle of economic and production practice, the optimum straw mulching quantity for summer maize was 7500 kg·hm-2 and the suitable soil moisture condition was to keep soil water content above 65% of field capacity.(6) On the basis of rainfall, reference crop evapotranspiration of different hydrological years, and the average crop coefficient of different mulching treatments from the experiment in 2007 and 2008, the net irrigation water requirement of different hydrological years for summer maize was calculated. The irrigation schedule of saving water and high efficiency for summer maize under different mulching conditions was proposed. In normal hydrological year, summer maize under different planting patterns needed to be irrigated two times, one was in seeding period, and the other at grain filling stage. Compared with CK, the irrigation time of PM and SM2 could be delayed, as well as PM and SM2 could reduce by one time of irrigation and save 750～900 m3·hm-2 of water in a drought year and an extremely desiccative year.
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