| Drought and water shortage has become a key factor which restriction increases China’s grainoutput. In the semi arid rainfed agricultural areas of the Northwest, water shortages has limited thedevelopment of local agricultural production seriously. How to find effective measures to improvelimited precipitation resource use efficiency of crop, which is becoming the key of local agriculturalproduction. The objective of this study was to disclose the effects of different plastic film mulchingtreatments on soil moisture, consumption characteristic, yield, water use efficiency, and dry matteraccumulation and distribution of winter and spring wheat under semi arid rainfed conditions in theDingxi of Gansu Province. In a continuous experiment across three growing seasons from2008to2011, we planted winter and spring wheat with different plastic film mulching treatments includingfilm mulched soil and bunch seeded (A), plastic dropping in hill (B), drilling beside plastic film (C),and compared with open drill seeding (CK). While spring wheat is divided into autumn mulchingand spring mulching. The result shows that:1. The plastic film mulching could significantly improve the moisture content of soil surfacelayer (020cm), and general the before jointing stage was greater than the after jointing stage, thefull plastic film mulching was greater than the half soil plastic film mulching, the autumn mulchingwas greater than the spring mulching, the winter wheat was greater than the spring wheat, Gangumode than other modes. The water content of the mulching on soil surface layer were1.49percentage point higher than the open field in whole growth period, while the water content of themulching on soil surface layer from the initial stage of wintering to the turning green stage were2.93.6percentage point higher than the open field, Gansu and Gangu modes were0.8percentagepoint higher than Shanxi mode, the autumn mulching was0.12percentage point higher than thespring mulching, the winter wheat was0.33percentage point higher than the spring wheat, andGangu mode was0.57percentage point higher than Gansu and Shanxi modes.The plastic film mulching could significantly increase the moisture content of soil surfacelayer (020cm), however, after jointing stage, the deep soil (below20cm) moisture content ofmulching was gradually lower than that of open field. From jointing to mature stage, the averagemoisture content of open field in20200cm was0.95percentage point higher than the mulching,and the average moisture content of the mulching in0200cm was1percentage point lower thanthe open field. Though the high grain yield of film mulching was based on high water consumption,the soil moisture of film mulching stubble field in0200cm could be fully restored to the level ofthe open field before seeding by water compensation of fallow period.Although the moisture content of planting patterns and each soil layer are assumes declining trend through with the growth stages, and it also found that the soil moisture content was showedthe former high low after the trend in individual session. The differences of mulching treatmentswere significantly lower than those between mulching treatment and open field contrast. Thebiggest difference exists in soil layers90200cm, and in growth stages were maturity stage.By comparison of the average moisture content of whole growth period in0200cm amongdifferent mulching methods, Gangu pattern was the highest and Shanxi pattern was the lowest ofwinter and spring wheat; the autumn mulching was higher than the spring mulching. But in differentperiods and soil layers, the soil moisture content was not entirely the same in order of frequency,that were close to each other the difference of consumption and operation deployment for differentplanting treatment.But, in general, the differences of winter wheat between mulching treatments were significantlysmaller than those between mulching treatment and open field contrast. While the differences ofspring wheat between the autumn mulching and the spring mulching in Gansu and Gangu modeswere significantly greater than the differences of Shanxi mode.2. The total water consumption amount soil water consumption amoun and its percentage tototal water consumption amount of winter and spring wheat under the plastic film mulching werehigher than that with conventional open field cultivation, and these were higher34.8%,198.2%,21percentage points and16.6%,44.4%,7.4percentage points than CK, which indicated that plasticfilm mulching was beneficial to improve the absorption of soil water. Before the jointing stage, thewater consumption percentage of the plastic film mulching were lower than the open field, but ithad the higher water consumption amount from anthesis to maturity and its water consumptionpercentage, which had favorable impact on water absorption during reproductive growth stage ofwheat.0200cm soil water consumption of winter and spring wheat are mainly concentrated inthe above120cm, but the differences were more obvious between the plastic film mulching and theopen field in the below120cm, showed the plastic film mulching can promote the absorption andutilization deep soil moisture of wheat. These indicators, Gangu mode is relatively obviousadvantages, Shanxi mode relative advantages of the worst, indicating that Gangu model on thehighest level of the effective use of water.3. Population dry matter accumulation of the plastic film mulching winter and spring wheatwere significantly higher than the open in different developing stages. single stem dry matteraccumulation were higher than the open before the flowering stage, after flowering spring wheatplastic film mulching than the open, but the winter wheat is not necessarily higher than the openfield.The maximum dry matter accumulation of populations in the anthesis stage, dry matter translocation amount to grains and its contribution to grains of winter and spring wheat treated withthe plastic film mulching were obviously higher than that with conventional open field cultivation,and these were higher112.9%,128.9%,12.5percentage points and66.6%103.8%9.0percentagepoints than CK. Plastic film mulching on improving grain contribution rate mainly throughpromoted the dry matter transform from leaf department (blade and sheath) and stalks to grain, butit would reduce the dry matter transport rate and contribution rate to grain of spike department(spike axis and grain husk). In the winter wheat, B had the highest dry matter accumulation andtranslocation, A had the highest contribution rate, and C had the lowest dry matter accumulation,translocation, transfer rate and contribution rate. In the spring wheat, about the dry matteraccumulation, translocation and contribution rate, the autumn mulching was higher than the springmulching, A was the highest, C was the lowest. The translocation rate differences of treatmentswere based on the different year. Although different plastic film mulching treatments in the anthesisstage, the dry matter accumulation and translocation amount of populations was significantly higherthan CK, but the single stem biomass accumulation and translocation in some mulched treatmentswas not necessarily higher than that of CK, and the differences between the treatments of a singlestem was far small in populations.4. Plastic film mulching could dramatically increase production and the output higher thanopen field of winter and spring wheat. With the average yield rate was49.4%53.2%of winterwheat, among the different mulching models, the output of Gansu mode was the frist, Gangu andShanxi modes stand the second and third places respectively. With the average yield rate was22.3%44.5%of spring wheat, the output of Gangu model was the frist, Gansu and Shanxi modelsstand the second and third places respectively, the autumn mulching was higher than the springmulching. Among the six models, the output of Gangu mode (49.7%62.5%) with membranemulching in autumn was the highest and output increasing was the most remarkable. |
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