【作者】 卜令铎；

【导师】 李世清； 陈新平；

【作者基本信息】 西北农林科技大学 ， 植物营养学， 2013， 博士

【摘要】 我国旱地总国土面积70%以上，干旱半干旱耕地占总耕地面积的43%，旱地作物生产是保障我国粮食安全的重要部分。然而，旱地作物的实际产量不到产量潜力的50%。随着人口的持续增加耕地面积的不断减少，粮食生产越来越倚重于作物单产的提高。与此同时，气候变暖和降雨持续下降将是21世纪旱地作物增产最严峻的挑战。因此，充分理解旱地作物高产的机理，不断优化旱地雨养农业水分管理措施，构建和完善旱地作物高产和资源高效利用的生产体系是保障粮食安全和生态环境可持续发展的关键。本研究以我国西北黄土高原典型旱作农业区的春玉米生产为研究对象，通过两年田间试验，验证Hybrid-Maize模型覆膜模块的适用性；以验证后的覆膜Hybrid-Maize模型为指导，量化并成功构建了耦合大气-作物-土壤的旱地春玉米高产高效栽培体系，并进行田间验证，明确旱地玉米增产的生理机制。同时利用历史气象资料和作物模型模拟探索黄土高原春玉米对气候变化的响应规律和适应措施。主要研究进展如下：（1）本文将具有覆膜模块的新版Hybrid-Maize模型应用于黄土高原旱地玉米的生产模拟。田间验证结果表明，该模型在灌溉、雨养和覆膜条件下对生物量和籽粒干物质积累过程的模拟值与田间实测值基本吻合，对总生物量和籽粒产量表现出较高的模拟精度。（2）利用校验后Hybrid-Maize模型对近50年长武地区的旱作春玉米产量潜力估算表明，在无水分限制条件下，当地春玉米产量潜力为14.1t ha^-1，在水分限制条件下为12.7t ha^-1，覆膜条件下的产量潜力为15t ha^-1。同时，基于气候资料和模型对当地春玉米品种、播种日期、种植密度、水分养分管理措施进行优化，构建了耦合土壤-作物-大气综合管理的旱地春玉米高产高效栽培体系。经过3年田间验证表明，该体系能够实现产量潜力，平均氮肥利用效率61kg kg^-1，平均水分利用效率为35kg ha^-1mm^-1。（3）砂砾和地膜覆盖能够显著提高土壤温度和水分含量，较大的叶面积指数增加了光能的捕获和利用，加快玉米营养生长期植株冠层的生长发育速度。因此，覆盖有效促进了干物质积累，从而获得较高的生物量、产量和资源利用效率。与传统的砂砾覆盖措施相比，地膜覆盖能够更有效的改善玉米苗期土壤水热状况，更适用于促进干旱半干旱地区春玉米增产。（4）覆盖处理显著加快了玉米植株的生长和发育进程。花期强壮的植株冠层和适宜的生长环境促进了粒数的增加；花期的提前直接导致籽粒灌浆周期的延长，促进了光热资源的捕获和利用，显著提高了籽粒干物质的同化和转移量，从而显著提高了粒重。因此，花期的提前是覆盖促进旱地春玉米增产的重要机制。（5）吐丝后揭膜能够缓解生殖生长期植株衰老，提高灌浆期冠层光合速率和干物质同化量，从而进一步增加了玉米总生物量、收获指数和籽粒产量。揭膜导致籽粒干物质的显著增加归因于吐丝后“源”（叶面积指数和光合速率）和“库”（穗粒数和粒体积）的协同增加。与玉米全生育期覆膜相比，吐丝后揭膜处理能够进一步提高玉米产量，更适用于玉米花后降雨充足的半干旱地区。（6）利用Hybrid-Maize模型对整个黄土高原春玉米生产的模拟研究显示，自1980年，黄土高原气温升高、辐射和降雨下降，导致春玉米产量潜力显著下降，并加剧当地雨养生产的水分亏缺。气温升高是玉米产量潜力下降的首要原因，（占产量潜力下降总量的68.7%），特别是玉米生殖生长期（7-9月）的升温显著缩短籽粒生长周期，直接导致减产；其中最低气温升高是降低产量潜力的主导因素，最高气温的升高是降低水分满足率，是加剧水分亏缺的主要原因。辐射下降是造成玉米产量潜力下降的次要原因（占产量潜力下降总量的24.6%）。年季间的降雨波动加剧了水分亏缺，是造成雨养生产水分亏缺的另一因素。（7）区域模拟显示，若不更新品种，近30年黄土高原地区春玉米生长季（4-9月）有效积温（>10°C）的持续升高将导致玉米生育周期显著缩短，其产量潜力和水分利用效率将持续下降。依据各区各年代4-9月的积温升高幅度确定的适应性品种（晚熟品种）能够充分适应升温环境，生育周期延长，产量潜力和水分利用效率持续提高，是应对黄土高原气候变暖的有效措施。此外，持续发展旱作农业保水措施（如地膜覆盖）有利于缓解未来降雨的下降，从而保障旱区的粮食安全和可持续发展。更多还原

【Abstract】 In China, arid regions account for>70%of total land area, taking up43%of the totalagricultural area, and are essential for its agricultural production. However, yield gaps, i.e.,the differences between potential and actual yields, are greater than50%in drylands regions.Continuous growth of the human population and the decline cultivated farmland will call for asignificant increase in crop yields per unit area. In addition, increasing temperatures anddeclining precipitation in semi-arid regions are likely to reduce yields of maize, wheat, rice,and other primary crops within the next two decades, and will be a huge challenge to China’sdrylands farm in the21st century. Hence, it is imperative for food security over the next fewdecades that we improve our understanding of the physiological mechanism of crop yieldrising, and continuing to improve rain-fed drylands agriculture with optimised watermanagement is a key priority to guarantee food security and eco-development sustainability.This study focused on the Loess Plateau, a typical semi-arid monsoon climate region, inwhich dryland farming is dominated by monoculture cropping systems. The applicability ofthe Hybrid-Maize model was tested using data from a twoe-year field experiment; and usedthe crop model to establish the high yield and high resource use efficiency （double-high）cultivation system of drylands maize production; and to determine the physiologicalmechanism contributing to yield improvement; as well as to assess tmaize productivityresponse to climate change and propose adaptive crop management strategies. This researchcould be helpful for water management strategies in maize production in semi-arid regions.The main results were showed as follow:（1） In this study, a new module for plastic film mulching in Hybrid-Maize model wasdeveloped to simulate maize growth development and grain yield of drylands farm. Theperformance of this modified Hybrid-Maize model was reasonably good in terms of biomassand grain dry matter. The Hybrid-Maize model can be used to simulate the yield potential ofmaize well under optimum irrigation, rainfed, and plastic film mulching conditions.（2） After modification the Hybrid-Maize model was used to simulate the yield potentialof maize in Changwu region over the last50years. The yields potential were14.1t ha^-1under no water limited condition,12.7t ha^-1under water limited conditions,15t ha^-1under plasticfilm mulching conditions, respectively. We use the Hybrid-Maize model to guide the optimizestructure of drylands maize cultivation systems: to adjust variety, sowing date, plantspopulation, and the management for water and nutrition of soil; and established the high yieldand high resource use efficiency cultivation system that integrated atmospheric resource–crop community–soil environment system management.3-years field tests indicated that,maize yield of the cultivation system have reached100%of yield potential, the nitrogen useefficiency was reached61kg kg^-1, the water use efficiency was reached35kg ha^-1mm^-1.（3） The mulch practices could significantly improve cumulative topsoil temperature andsoil moisture, thereby synchronising larger leaf area index （LAI） and greater radiationinterception with earlier development and rapid plant growth during the early VS stage.Consequently, these mulching practices are effective at improving the amounts ofaccumulated dry matter, leading to significantly greater final biomass, grain yield, and wateruse efficiency （WUE）. Compared to conventional gravel mulching, plastic film mulchingcould be more effective to increase the topsoil temperatures and the conservation of availablesoil water in spring. Additionally, this technique represents a more effective approach toimproving spring-sown maize yield in semi-arid regions.（4） Mulching treatments markedly accelerated plant growth and flowering, whichdirectly resulted in a longer grain-filling period. The robust plants and better growthenvironment during flowering increased the number of kernels. The prolonged growth periodsallowed greater resource interception and use efficiency of both heat and solar radiation,thereby inducing greater assimilation and translocation for grain growth and resulting inhigher final kernel weight. We concluded that the mulching treatments improved grain yieldsas a direct consequence of earlier flowering.（5） The mulching removed （RM） compared to the plastic film mulching （FM） treatmentincreased maize biomass, harvest index, and grain yields values with delayed crop senescenceresulted in greater photosynthetic assimilation during the grain filling period. Either greatersource capacity from the significantly higher LAI and photosynthetic rate, or stronger sinkcapacity due to more kernel numbers and larger kernel volume expansion contributed togreater dry matter accumulation to the grain. In comparison to the FM treatment, the RMpractice can increase grain yields further, thus should be considered in the semiarid monsoonclimate region where rain is sufficient during the reproductive stage of maize.（6） Climatic warming has increased significantly since the1980s on the Loess Plateau,meanwhile the solar radiation and precipitation declined. These climate trends may lead to thereduction in yield potential and induced the serious water deficits. The warming trends have significant reduced the crop growth duration, induced68.7%of the total yield potentialdeclined, was the most important factor in the reduction in yield potential. Notably, the risingminimum temperature was mainly reason for climate warms and the most important factor inthe reduction in yield potential, while the rising maximum temperature may be the mainlyreason for the serious water deficits. In addition, the declining solar radiation decreasedavailable energy of assimilates for plant growth, induced24.6%of the total yield potentialdeclined, was the secondary factor in the reduction in yield potential. The annual fluctuationsand decline trends of precipitation will aggravate the water deficits across the Loess Plateau.（7） The magnitude of warming, since the1980s, may lead to a reduction in growthduration, yield potential and water use efficiency （WUE） if maize varieties remainedunchanged. We suggest the adapted later maturing cultivars, based on the increases incumulative temperatures for the period April–September in each of the decades in all studyregions. The adapted varieties allowed the longer growth duration, increasing yields potential,and higher WUE, and will be an effective way to fit within the warming environment. Inaddition, continuing to develop water harvesting techniques （e.g., plastic film mulching） willhelp to offset decreasing rainfall, and to guarantee food security and sustainability in aridregions.In a word, our results have confirmed the feasibility that used the Hybrid-Maize model toguide the optimizing of maize production system, improved our understanding of thephysiological mechanism of crop yield rising, assessed the potential impacts of climatechange, and proposed the adaptation strategies to mitigate the negative impacts. This researchcould be helpful for improve crop production in semi-arid regions.更多还原