本文選題：穩(wěn)定同位素 + 玉米農(nóng)田��； 參考：《中國(guó)農(nóng)業(yè)大學(xué)》2017年博士論文

【摘要】：水資源短缺已成為影響地區(qū)農(nóng)業(yè)經(jīng)濟(jì)可持續(xù)發(fā)展的嚴(yán)重障礙。隨著節(jié)水灌溉技術(shù)和覆膜技術(shù)在干旱地區(qū)的推廣,研究覆膜灌溉條件下農(nóng)田土壤-植物-大氣(SPAC)水分循環(huán)的機(jī)理,分析覆膜條件下土壤水分的傳輸和轉(zhuǎn)化及作物水吸收利用過(guò)程,闡明作物水分利用效率的提升機(jī)制,對(duì)旱區(qū)水資源科學(xué)配置與調(diào)控具有重要的意義。本研究以制種玉米農(nóng)田為研究對(duì)象,采用水同位素分析儀、多通道大氣水汽冷阱、渦度相關(guān)系統(tǒng)和包裹式植物莖流計(jì)等設(shè)備。結(jié)合同位素守恒和水量平衡原理、同位素IsoSource模型、Keeling plot模型、Craig-Grodon模型以及Rayleigh蒸餾模型,對(duì)交替溝灌(AFI)、常規(guī)溝灌(CFI)、畦灌(BI)和交替溝灌1/2灌水量處理(AFI(M/2))等條件下土壤水分運(yùn)動(dòng)規(guī)律、玉米根系吸水模式、土壤-大氣水分傳輸和轉(zhuǎn)化機(jī)制以及農(nóng)田蒸發(fā)蒸騰量的估算和區(qū)分等進(jìn)行了深入系統(tǒng)的試驗(yàn)研究,取得以下成果:(1)擬合了西北旱區(qū)降水線 LMWL:δD=7.4δ18O+8.0(R2=0.95)和土壤水線 SWL:δD = 5.6δ18O-9.9(R2=0.90),明確了土壤水、植株水和大氣水汽的氫氧同位素分布特征和時(shí)空變化規(guī)律。降水線截距和斜率均小于全球降水線,表明了當(dāng)?shù)剌^高的蒸發(fā)強(qiáng)度和蒸發(fā)速率。土壤水氫氧同位素在垂直方向剖面呈現(xiàn)明顯的梯度分布,隨土層深度增加而變小。玉米植株各部位同位素組成存在顯著差異,葉脈與木質(zhì)部水分同位素不發(fā)生分餾。作物蒸騰水汽同位素及其水汽濃度是影響農(nóng)田背景水汽同位素組成的主導(dǎo)因素。(2)進(jìn)一步揭示了交替溝灌提高作物水分利用效率和產(chǎn)量的機(jī)理。不同灌溉條件下玉米根系吸水模式存在顯著差異,玉米主要吸水深度為:AFI(M/2)AFICFIBI。玉米全生育期內(nèi),影響其根系吸水的主導(dǎo)因素是根系分布,而在一個(gè)灌溉周期內(nèi),影響玉米根系吸水的主導(dǎo)因素是土壤水分。玉米出現(xiàn)干旱脅迫后,濕潤(rùn)根區(qū)的水分優(yōu)先供應(yīng)地上部分組織再進(jìn)行橫向運(yùn)輸。AFI條件下作物吸收深層和濕潤(rùn)側(cè)土壤水分比例提高4-26%,減少水分滲漏損失,玉米產(chǎn)量相應(yīng)的提高了 17.0-30.4%。當(dāng)減少50%的灌溉水量時(shí),AFI(M/2)不明顯減少產(chǎn)量,作物的水分利用效率顯著提高 13.3-33.8%。(3)建立了覆膜條件下土壤蒸發(fā)的同位素模型,定量分析了覆膜條件下農(nóng)田土壤蒸發(fā)水分相變過(guò)程。覆膜條件下,土壤蒸發(fā)前緣主要發(fā)生在5-10 cm 土層,蒸發(fā)水汽分子通過(guò)土壤孔隙向上擴(kuò)散,部分水汽分子被0-5 cm的土壤水吸附并與其水分子發(fā)生交換進(jìn)而擴(kuò)散到外界。玉米全生育期平均4.5%的膜下土壤水分發(fā)生蒸發(fā)并形成水汽,其中72.6%蒸發(fā)水汽在膜下冷凝形成凝結(jié)水,其中70.0%發(fā)生二次蒸發(fā)再次形成水汽擴(kuò)散到外界,平均蒸發(fā)量約為0.80 mm/d,蒸發(fā)比例FE約為21.2%。覆膜條件下,裸土面積占的比例雖然很小(0.5-5%),但土壤蒸發(fā)比例依然較大。(4)提出了基于穩(wěn)定同位素的農(nóng)田蒸發(fā)蒸騰量估算和區(qū)分的新方法。實(shí)現(xiàn)了在同位素穩(wěn)定狀態(tài)(ISS)和非穩(wěn)定狀態(tài)(NSS)下對(duì)玉米植株蒸騰水汽的同位素組成δT直接而連續(xù)的測(cè)定�；诜�(wěn)定同位素方法對(duì)農(nóng)田蒸發(fā)蒸騰量的估算和區(qū)分表明,玉米蒸騰比例(FT)隨季節(jié)變化較大,在生育前期較小中期較大,到后期緩慢下降。玉米全生育期內(nèi)蒸騰比例范圍為52-91%,平均值為78%。蒸騰比例(FT)與葉面積指數(shù)(LAI)具有良好的非線性關(guān)系:FT=0.71LAI0.14,葉面積指數(shù)LAI可以作為一項(xiàng)重要的指標(biāo)用于衡量植被的蒸騰比例和評(píng)估作物耗水關(guān)系。
[Abstract]:Water shortage has become a serious obstacle to the sustainable development of agricultural economy in the region. With the popularization of water-saving irrigation technology and film mulching technology in arid areas, the mechanism of soil plant atmosphere (SPAC) water cycle under the condition of film mulching irrigation is studied. The transmission and transformation of soil moisture under the condition of mulching and the absorption and utilization of crop water are analyzed. The process, clarifying the mechanism of raising water use efficiency of crops, is of great significance to the scientific allocation and regulation of water resources in dry areas. In this study, a water isotope analyzer, a multi-channel atmospheric water vapor trap, a vorticity related system and a parcel plant stem flow meter were used in the study of maize cropland. Quantity balance principle, isotopic IsoSource model, Keeling plot model, Craig-Grodon model and Rayleigh distillation model, soil moisture movement law, maize root water absorption pattern, soil air water transport and transformation mechanism, under the condition of alternate furrow irrigation (AFI), conventional furrow irrigation (CFI), border irrigation (BI) and alternate furrow irrigation 1/2 irrigation (AFI (M/2)). The results are as follows: (1) fitting the precipitation line LMWL: Delta D=7.4 Delta 18O+8.0 (R2=0.95) and soil waterline SWL: Delta D = 5.6 Delta 18O-9.9 (R2=0.90) in northwest dry area, and the distribution characteristics of hydrogen and oxygen isotopes of soil water, plant water and atmospheric water vapor, and the time and space of time and space are clearly defined. The intercept and slope of the precipitation line are smaller than the global precipitation line, which shows the high local evaporation intensity and evaporation rate. The soil water hydrogen and oxygen isotopes show a distinct gradient distribution in the vertical direction and smaller with the increase of soil depth. There are significant differences in the isotopic composition of different parts of the maize plants and the moisture of the leaf vein and xylem. Isotopes of isotopes are not fractionated. Crop evapotranspiration and water vapor isotopes and water vapor concentration are the dominant factors affecting the composition of water vapor isotopes in farmland. (2) the mechanism of increasing crop water use efficiency and yield by alternate furrow irrigation is further revealed. There is significant difference in the water absorption pattern of maize root system under different irrigation conditions and the main water absorption depth of Maize In the whole period of AFI (M/2) AFICFIBI., the dominant factor that affects its root water absorption is the distribution of root system. In a period of irrigation, the dominant factor affecting the water absorption of maize roots is soil moisture. After the drought stress of maize, the water in the moist root region is given priority to the part of the soil and then transversely transport the crops under the condition of.AFI. The ratio of soil moisture absorption in deep and humid sides increased by 4-26%, reducing the loss of water leakage. The corresponding increase of maize yield by 17.0-30.4%. when 50% of the irrigation water was reduced, AFI (M/2) did not decrease the yield obviously, and the water use efficiency of the crop was significantly increased by 13.3-33.8%. (3), the isotopic model of soil evaporation under the condition of mulching was built, and the quantitative analysis was established. The process of evaporation and moisture transformation in farmland soil under the condition of film mulching was analyzed. Under the condition of film mulching, the evaporation front of the soil mainly occurred in the 5-10 cm soil layer. The evaporation water vapor molecules spread upward through the soil pore. Some of the water vapor molecules were adsorbed by 0-5 cm soil water and exchanged with the water molecules to spread to the outside world. The average growth period of maize was 4.5%. The soil moisture under the membrane evaporates and forms water vapor. 72.6% of the evaporation water vapor condenses under the film to form condensate, and 70% of them evaporates two times to form water vapor to spread to the outside world, and the average evaporation is about 0.80 mm/d, and the proportion of evaporation is about FE under the condition of 21.2%. covering, although the proportion of bare soil area is very small (0.5-5%), but soil evaporation The proportion is still large. (4) a new method of estimating and distinguishing the evapotranspiration of farmland based on stable isotopes is proposed. The direct and continuous determination of isotope composition of transpiration of maize plants under the isotopic state (ISS) and the unstable state (NSS) is realized. The estimation of the evapotranspiration based on stable isotope method is used to estimate the evapotranspiration of farmland The calculation and distinction showed that the transpiration ratio (FT) of maize was larger with the season, and it was larger in the small and medium period of the early growth period and slowly declined in the later period. The transpiration ratio of Maize in the whole growth period was 52-91%, and the average value of 78%. transpiration ratio (FT) and leaf area index (LAI) had a good nonlinear relationship: FT=0.71LAI0.14, the leaf area index LAI could be used as a LAI. An important indicator is used to measure the transpiration ratio of vegetation and to assess the relationship between crop consumption and water consumption.
【學(xué)位授予單位】：中國(guó)農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：S513

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本文編號(hào)：2103529