| Two experiments have been conducted in no-weighting lysimeters under arain-shelter and a large-scale weighting lysimeter with wheat cultivar of Aikang58and summer maize cultivar of Zhengdan958to explore evapotranspiration and itsregulation effect of winter wheat-summer maize cropping system in Huanghuai area.Two factors was applied in no-weighting lysimeters experiment with the main factoras straw treatment regime (totally returning and none returning) and the subsidiaryfactor as water supply (soil water content account for40%,50%,60%,70%fieldwater capacity in winter wheat field and soil water content account for50%,60%,70%,80%field water capacity in summer maize field). The results were listed asbelow:1. Annual evapotranspiration of winter wheat-summer maize cropping systemshaped M annually, which peaked at jointing stage to heading stage of winter wheatand jointing stage to tasseling stage of summer maize. Daily maximumevaportranspiration was7mm·d-1and9.5mm·d-1. Annual evapotranspiration understraw returning was less than that measured by large-scale weighting lysimeter by28.93mm. In winter wheat, evapotranspiration under straw returning and no-strawreturning was less than that measured by large-scale weighting lysimeter by73.39mm and92.08mm. The difference between straw returning and no-straw returningfirstly increased and then decreased along with water supply. It was the highest underW3treatment for36.67mm.2. Straw returning significantly increased soil water content, soil water storageand water use efficiency, and decreased crop water consumption under winterwheat-summer maize cropping system. Soil water content and soil water consumptionincreased along with increased water supply. Straw returnning mainly reduced soilwater consumption and water consumption coefficient in prior growth stage and lategrowth stage of winter wheat, thereby significantly improved water use efficiency, especially irrigation water use efficiency. In summer maize, straw returnning mainlyreduced evaporation in vegetative growth stage, thereby significantly decreased waterconsumption and improved water use efficiency. Water use efficiency was the highestunder W3treatment, which was420.68kg·hm-2·mm-1and24.11kg·hm-2·mm-1understraw returning and no-straw returning.3. Straw returnning significantly increased leaf area index andphotosynthesis parameters of winter wheat and summer maize. Leaf area index,SPAD, Pn and Tr increased along with increased water supply under the same strawtreatment regime. Straw returnning significantly increased filling rate of winter wheatin the former and later periods by40.56%and84.00%than no-straw returning, whichwas the highest under W3water treatment. In terms of summer maize, Pn has nosignificant difference between W3and W4treatment under straw returnning in12thstage, and it was significantly higher than other treatments in tasseling stage. Strawreturnning significantly increased leaf, stem, cob, grain and aboveground dry matterweight per plant. Increased water supply could promote assimilation transfering tograin of summer maize.4. Straw returnning, water regulation and their interaction had a significant effecton ear length,1000-grain weight and yield of winter wheat. Straw returnningsignificantly increased winter wheat yield by increased grain number per ear,1000-grain weight and effective tillers. Water regulation significantly raised winterwheat yield by increased grain number per ear. In summer maize, straw returnningsignificantly decreased grain nitrogen content and grain protein content, wihlesignificantly increase yield protein content. Yield protein content reached themaximum under W3treatment. Straw returnning significantly increased yieldby rows per ear and grains per row. Water supply triggered the rows per ear, grainsper row,100-grain weight increase thereby increased yield of summer maize. Eardiameter reached the maximum under W3treatment. Tip length reached the minimamunder W3treatment. Ear characters under straw returnning with W3treatmentperformed the best and its yield was significantly higher than W3and W4by7.30%and2.58%under no-straw returning, while it had no significant difference with W4under straw returning, which indicated that straw returnning with W3treatmentshowed the best perfoemence in Huanghuai areas. |
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