【作者】 王振昌；

【导师】 康绍忠；

【作者基本信息】 西北农林科技大学 ， 农业水土工程， 2012， 博士

【摘要】 我国西北干旱荒漠绿洲区水资源极度紧缺，灌溉农业用水量占总用水量的比例较高。研究作物节水高效利用技术，对于促进该地区的水资源持续高效利用，实现生态系统良性循环以及经济社会的可持续发展具有重要的意义。本论文以该地区蓬勃发展的制种玉米为研究对象，通过室内盆栽试验、室外盆栽试验与田间小区试验相结合的方式，应用HPFM根系导水率仪器、ANCA-SL元素分析仪等先进仪器，获取了制种玉米的生理生态、气象因素、土壤状况等指标，并对分根区交替灌溉（Alternate Partial RootzoneIrrigation, APRI）灌溉方式下气孔导度模型进行了初步探索，取得如下主要研究成果：（1）探讨了相同灌水量，制种玉米在APRI灌溉方式下，能够比DI显著提高潜在水分利用效率（Intrinsic Water Use Efficiency, WUEi）的机理。通过两种灌溉方式，即APRI和常规亏缺灌溉（Deficit Irrigation, DI）在三种不同的氮素水平（75，150和300mgN Kg-1土壤）的试验表明，APRI处理下叶片中的碳同位素分辨率(Isotope discrimination,Δ¹³C)和维管束鞘细胞的泄漏率（Φ）均显著低于DI处理，然而胞间CO₂浓度与大气中CO₂浓度的比值（Ci/Ca）并没有受到氮素水平和灌溉方式的影响。APRI处理下制种玉米叶片的羧化效率（Carboxylation Efficiency, CE）以及在CO₂饱和状态下的光合速率（Asat）显著高于DI。在APRI处理中，其羧化效率（CE）以及Asat的显著提高与Φ的显著降低有关。（2）研究了不同氮素水平，APRI、DI以及常规充分灌溉（Full Irrigation, FI）条件下木质部汁液中的pH值、ABA浓度、阴、阳离子浓度的相互作用，以及其对气孔导度的影响。当木质部汁液中的NO—3浓度从亏缺（N1水平）到最优（N2水平），以致到奢侈状态（N3水平）时，木质部中的pH值表现为先下降后上升的趋势；与木质部汁液中的pH值相似，其ABA浓度也表现为在N2水平下最小，N1和N3水平下较大。在N3水平下，DI和APRI均显著低于其在N1和N2水平的气孔导度，然而FI在三种氮素水平（N1，N2，N3水平）均无显著差别，这表明木质部汁液中的pH、ABA浓度以及各种无机离子浓度相互作用共同调控着气孔的开闭。同时还发现，木质部汁液中的Ca2+浓度与气孔导度显著线性负相关，这表明可能Ca2+也是一种调控气孔开闭的根冠信号。（3）初步揭示了APRI灌溉方式下制种玉米提高氮素吸收能力的原因。APRI促进制种玉米根系对氮素吸收的主要原因可以总结为两点：①APRI促进了根系的生长，增大了根系表面积和根冠比，提高了根系导水率。通过2009年的试验可知，APRI相对于DI，根系导水率（Root hydraulic conductivity, KR）提高了30%。2010年的盆栽试验以及2009年的大田试验表明APRI提高了根系表面积和根冠比；②APRI有利于土壤中有机氮素的矿化，提高了土壤中的可利用的氮素量。植株和叶片中的δ15N的含量，可以作为土壤中有机氮的矿化程度的指标。APRI和FI的叶片氮素累积量显著大于DI处理，其δ15N也显著高于DI处理。（4）揭示了制种玉米叶绿素含量指标（CCI）与叶片的氮素浓度以及光合能力均显著线性相关。随着CCI和叶片氮素浓度的增加，最大相对气孔导度（gmax Rel）显著增加。同时试验数据还表明，随着叶-气温差（T_l-T_a）的增大，gmax Rel逐渐缩小，当T_l-T_a为4.5℃时，气孔几乎完全关闭，然而在T_l-T_a为-2℃，其能够达到该生育期内最大的气孔导度。经过回归分析可知，T_l-T_a与太阳辐射强度（Q）存在着正相关，而与空气饱和水汽压差（VPDair）和土壤水势（Ψs）存在负相关。（5）通过在Jarvis模型中增加与制种玉米生理状态相关的叶绿素指标（CCI）参数以及代表不同灌溉方式的土壤水势参数，可以使APRI条件下的气孔导度模_拟效果更加精确。模拟值和实测值的比较表_明，改进的气孔导度模型的平均预测值（P）比Jarvis初始模型更接近实测平均值（Q），其修正效率系数（E1），修正一致性指标（d1）相对于初始模型分别提高了30%和6%。通过在Jarvis模型中增加表示水力信号和非水力信号的平均土水势以及CCI参数，可以增加气孔导度的模拟精度。更多还原

【Abstract】 Water resource is limited in the desert oasis area of northwest China. In order to improvethe water use efficiency in this area, water-saving methods have been widely used. Alternatepartial rootzone irrigation was developed recently and was confirmed to be a successfulwater-saving irrigation regime. In this thesis, maize for seed under APRI was studied by potexperiment in green house, pot experiment in the semi–field and field experiment to get thesoil water content、weather parameters、morphology parameters and physiology parameters ofmaize for seed plants using advanced equipment such as TDR、ANCA-SL Elemental Analyserand20-20Tracer Mass Spectrometer et al. According to the findings in experiments, a revisedJarvis model was successfully set to simulate the stomatal conductance under APRI. In thisthesis, we got several results as shown in following:（1） The physiological basis for the advantage of alternate partial root-zone irrigation（APRI） over common deficit irrigation （DI） in improving crop water use efficiency （WUE）was studied in this thesis. Leaf gas exchange characteristics and photosynthetic CO₂–responseand light–response curves for maize （Zea mays L.） leaves exposed to PRI and DI wereanalysed under three N-fertilization rates, namely75,150, and300mg N kg-1soil.Measurements of net photosynthetic rate （An） and stomatal conductance （gs） showed that,across the three N-fertilization rates, the intrinsic WUE was significantly higher in APRI thanin DI leaves. Analysis of the CO₂–response curve revealed that both carboxylation efficiency（CE） and the CO₂-saturated photosynthetic rate （Asat） were significantly higher in PRI than inDI leaves across the three N-fertilization rates; whereas the N-fertilization rates did notinfluence the shape of the curves. The enhanced CE and Asat in the PRI leaves wasaccompanied by significant decreases in carbon isotope discrimination （Δ13C） andbundle-sheath cell leakiness to CO₂（Φ）. Analysis of the light–response curve indicated that,across the three N-fertilization rates, the quantum yield （α） and light-saturated grossphotosynthetic rate （Amax） were identical for the two irrigation treatments; whilst theconvexity （κ） of the curve was significantly greater in APRI than in DI leaves, which coincided with the greater CE and Asat derived from the CO₂–response curve at aphotosynthetic photon flux density of1500μmol m-2s-1. Collectively, the results suggest that,in comparison with the DI treatment, APRI improves photosynthetic capacity parameters CE,Asat, andκof maize leaves and that contributes to the greater intrinsic WUE in those plants.（2） The effects of alternate partial root-zone drying （APRI） irrigation as compared withconventional deficit irrigation （DI） and full irrigation （FI） on leaf nitrogen （N） accumulationwere investigated in maize （Zea mays L.） grown under three N-fertilization rates. The resultsshowed that neither irrigation nor N-fertilization treatments influenced shoot biomass andplant leaf area; while APRI plants had the highest root biomass and root to shoot ratiocompared to DI and FI plants. Increase of N rate significantly increased leaf N accumulation;across the N-fertilization rates, APRI and FI plants accumulated significantly greater amountof N in leaves than did DI plants. Leaf15N decreased significantly with increasingN-fertilization rate, and was significantly higher in PRD and FI than in DI plants. Water useefficiency （WUE） was the highest in APRI, followed by DI and the lowest in FI; whileN-fertilization rate had no effect on WUE. It was concluded that an enlarged root system andan enhanced soil N availability under APRI might have contributed to the greater Naccumulation in maize leaves.（3） The effects of Alternate partial root zone Irrigation （APRI） as compared with deficitirrigation （DI） and full irrigation （FI） on pH, ABA, nitrate and other ion concentrations inxylem sap using ‘root pressure’ method51days after treatment （DAT） and their relationshipswith stomatal conductances （gs） were investigated in maize plants （Zea mays L.） grown underthree N-fertilization rates. The results showed that response of pH in xylem sap to increasingN concentration from deficient to sufficient to supra-optimal is biphasic, which decreasesfrom deficit to optimal N, and then increase again as N increase further. The ABAconcentration in the xylem sap showed the same trend with pH with the increase of Nconcentration in xylem sap. Increasing the nitrate （N） concentration above optimal （N3level）decreased stomatal conductance compared with treatments in N2and N1level in maizeseedlings （Zea mays L.） growing in DI and APRI, but not for the treatment of FI, whichindicate that the pH,ABA and N signals might interact together to affect the gs. Across Nlevels, the value of gs for FI is the highest, followed by DI and APRI. Through analyzing therelationship between comprehensive component in xylem sap and gs, we found that exceptABA, calcium might be also a root-to-shoot signaling in controlling stomatal conductance.（4） There were significant linear relationships between CCI and N concentration inmaize leaves, as well as photosynthesis capacity. With the increase of CCI and Nconcentration in leaves, the relative maximum stomatal conductance for leaves （gmax Rel） was significantly increased. gmax Reldecreased gradually with the increase of differences betweenleaf and air temperature （T_l-T_a）,. When the value of （T_l-T_a） was-2℃, the gmax Relcould get tomaximum stomatal conductances during the growing seasons. From the regression analysis,we could find there were positive relationships between （T_l-T_a） and Q, but （T_l-T_a） werenegatively related to VPD and Ψs（5） With adding the CCI parameter related to physiology situation of leaves and Ψsparameter relating to hydraulic and chemical signaling in Jarvis model, the stomatalconductances of maize plants under APRI were successfully simulated. The E1and d1formodified Jarvis model was improved30%and6%, respectively, compared with the originalJarvis model.In conclusion, APRI has the potential to be applied in the arid area of northwest Chinafor saving water and increasing WUE. With adding the average soil water potential for wetand dry compartment of APRI representing the combined function of hydraulic andnon-hydraulic signaling and CCI which represent the physiology situation of leaves, themodified Jarvis model improved the accuracy of simulated stomatal conductances underAPRI.更多还原