| Water shortage was the key factor that was restricting the spring wheat production inDesert-oasis of northwest China. So, if the water resources sustainable development wasrealized and the efficient or water-saving oasis agriculture was build that the growthcharacteristics and the pattern water requirement of spring wheat was mastered. Andfinding the reasonable effective water-saving measures and determines optimal irrigationsystem for soil and climate conditions in the region and establishes the optimum plantingpattern. This paper analyzed the relationship between water use efficiency, waterconsumption and production as well as influencing factors of water use efficiency whichbased on the analysis of spring wheat growth characteristics, water requirement and lightcharacteristics. And then clarify the water consumption and the interactions of growthcharacters under the various control modes. This study set six irrigation treatments andfour mulch modes. such as, W1(240mm)、W2(300mm)、W3(360mm)、W4(420mm)、W5(480mm)、W0(0mm)；Film mulch(B)、Straw mulch(M)、Stone mulch(S)and CK. Theirrigation quantity of mulch treatments was360mm. The mainly results as follow:(1)The irrigation quota directly affected the plant height, leaf area index andaboveground and belowground biomass and grain yield of spring wheat. The grain yield indescending order was: W4>W5>W3>W2>W1>W0. The descending order of the water useefficiency (WUE) was W4>W3>W1>W2>W5>W0. There were quadratic curve equationbetween yield and water consumption (ET), water use efficiency (WUE).the maximumvalue of water use efficiency and grain yield was W4(420mm) treatment so that it wasbest suitable for irrigation in the region.(2)The grain yield and thousand grain weights in descending order was: B>S>CK>M.Comparing the CK treatment, the grain yield of B treatment was increased by2.2%~10.9%.And the grain yield of S treatment was increased by0.86%~0.35%. The grain yield of M treatment was increased by-6.9%~9.4%. So, B treatment compared with other treatmentswas better to improve crop yields, under the same conditions to achieve high purposes.(3) According to the water balance method, the wheat water consumption of springwheat was490mm to650mm under the different irrigation treatment. The maximumvalues of Water consumption was in the periods of the jointing late~pre-heading andheading late~pre-filling stage. The evapotranspiration (ET) in descending order wasW5>W4>W3>W2>W1>W0. Respectively, crops transpiration (T) of W0accounted for66.16%of total ET. W1accounted for79.60%of total ET. W2accounted for80.64%oftotal ET. W3accounted for81.25%of total ET. W4accounted for80.58%of total ET. W5accounted for81.26%of total ET. Mulch treatments, the water consumption of springwheat in descending order was CK>S>B> M.(4)The diurnal variations of spring wheat’s photosynthetic rate in the descendingorder was W4>W5>W3>W2>W1>W0; the diurnal variations of photosynthetic rateshowed a single peak curve trend in W3, W4, and W5. But photosynthetic rate of W1, W2,and CK showed bimodal curve, the “lunch break " phenomenon. So, higher waterirrigation treatments could effectively restrain the "lunch break" phenomenon of springwheat.Jointing and filling stage was the peak periods of spring wheat photosyntheticrate.In mulch treatments, the diurnal variations of spring wheat’s photosynthetic rate werein the descending order. Such as, was B>S>CK>M. and photosynthetic rate showed asingle peak curve characteristics. Excessive drought and excessive irrigation were notbeneficial to improve the photosynthesis of spring wheat.There were the quadraticrelationship between Transpiration rate (Tr), stomatal conductance (Cond), soil watercontent (W), solar radiation (PAR) and leaf net photosynthetic rate (Pn). The result ofprincipal component analysis showed that the key affected environmental factors of thewater use efficiency of spring wheat were the photosynthetic rate, transpiration rate, and airtemperature and soil moisture under different irrigation treatments. However, underdifferent mulching treatments, leaf temperature,5cm soil temperature and soil moisturewere the important environmental factors affected the water use efficiency of spring wheat.Film mulch (B) treatments were better to maintain soil temperature than other treatments.It was beneficial to help maintain soil moisture by Straw mulch (M).(5)Farquhar model was used to simulate net photosynthetic rate (Pn) of different irrigation and mulch treatments of Spring Wheat. And the light compensation point andlight saturation point, and other photosynthetic parameters could be calculated by theFarquhar model. Experimental data showed that the maximum photosynthetic rate of W4treatment had a maximum light saturation point (39.8μmol CO2m-2s-1) and a minimumlight compensation point (2.32μmol CO2m-2s-1). Film mulch (B) was more conducive toimproving maximum net photosynthetic rate of spring wheat than others. Therefore, W4(240mm) Irrigation and Film mulching (B) treatment of spring wheat had a better the lightecological adaptability than any other treatments.(6)The growth characteristics of spring wheat plant height, leaf area index, andaboveground biomass were conforming to the characteristics of classic Logistic curve withanalysis. So, the new modified Logistic modes were built by plant height (H) as theindependent variable. The leaf area index (L) and aboveground biomass (B) can becalculated easily by the new modified Logistic model. And according to the parameterscharacters of the CK and mulching treatments, a cover factor k was proposed. Therefore,the functional relationship between CK and mulching treatments was established by theclassic Logistic. By The error test and correlation analysis, simulation and measured valueshad a higher degree of agreement. The amendment logistic model can well simulate cropleaf area index and aboveground biomass by the faction of height as the independent(7) Aquacrop models was used to simulate the soil moisture, canopy cover,aboveground biomass and grain yield of the spring wheat under different irrigationtreatments in Desert-oasis. The results showed that the simulated values were agreed wellwith the observed values. And the simulation accuracy of the high water irrigationtreatments is better than the low water irrigation treatments. Therefore, Aquacrop modelcan be used to simulate the crop growth and soil moisture change process in this region. |
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