夏玉米干旱发生发展过程及其定量研究

发布时间：2018-01-30 05:36

本文关键词： 夏玉米苗期土壤水分干旱过程阈值干旱程度　出处：《中国气象科学研究院》2017年博士论文　论文类型：学位论文

【摘要】：干旱是世界范围内限制作物生长发育及产量形成的最主要因素。提高对作物干旱发生发展的辨识及受旱程度的评估能力,对采取科学的防旱抗旱措施,保障粮食安全具有重要意义。现有作物干旱研究主要集中在影响评估方面,且以定性分析为主、定量评价较少,对干旱发生发展过程认识不足。本研究以夏玉米为例,于2014年开展了夏玉米三叶期开始的6个初始土壤水分梯度的持续干旱实验,考察了不同持续干旱过程中土壤水分的变化规律及其对夏玉米植株水分状况(茎、叶含水率)、叶片气体交换(净光合速率Pn,蒸腾速率Tr和气孔导度Gs)、形态特征(叶面积,株高)、生物量(根、茎、叶和总干重)、干物质分配(根冠比,叶茎比)、发育期、产量形成以及叶片性状(叶面积,叶含水量,叶干重,叶片数)权衡生长的影响,明确了夏玉米对土壤水分的响应规律,揭示了夏玉米干旱发生发展过程,提出了干旱强度与干旱程度的定量表达,实现了夏玉米受旱程度的分级评价。主要结论如下:(1)夏玉米植株水分状况和叶片气体交换参数主要受当前土壤水分亏缺即干旱强度的影响,而夏玉米形态特征和生物量主要受累积水分亏缺即干旱程度的影响。(2)采用正态总体统计容忍限方法确定了引起夏玉米苗期茎、叶含水率、蒸腾速率、光合速率、气孔导度和叶面积发生显著性变化的临界土壤相对湿度(0～30cm)分别为72%、65%、62%、60%、58%和 46%。(3)阐明了夏玉米干旱发生发展过程:土壤水分不足会直接影响茎含水率,并通过茎含水率间接影响叶含水率,叶含水率会直接影响叶片的光合作用和叶面积扩张,其影响在植株个体水平上表现为叶面积的改变,而叶面积的大小会影响植株蒸腾作用以及辐射能的吸收,进而影响夏玉米的干物质积累。(4)提出了基于作物水分胁迫系数的干旱强度的定量表达。干旱强度与植株水分和叶片气体交换参数呈显著线性关系,且叶片气体交换较植株水分对干旱的敏感程度大,其中GsTrPn、茎含水率叶含水率。(5)考虑干旱强度随干旱持续时间的累积影响,提出了干旱程度的定量表达。采用阈值指标分类分析法(TITAN),集合夏玉米形态特征(叶面积,株高)和生物量(茎干重、叶干重和总干重)对干旱程度的响应规律,将夏玉米受旱程度划分为无旱、轻旱、中旱和重旱4个等级。(6)干旱会影响夏玉米根、茎、叶的相关生长以及叶片性状(叶面积,叶含水量,叶干重和叶片数)的权衡生长,体现了夏玉米对干旱的适应性。随着干旱程度的增加,夏玉米优先根系生长,其次是叶片,然后是茎。夏玉米会通过降低叶片含水量和叶面积来抑制叶片代谢活性和水分散失,降低生长速率,减少生长消耗以维持生存,反映出随着受旱程度加剧,夏玉米会采取降低生长速率,增加资源贮存以提高其生存能力的适应对策。
[Abstract]:Drought is the most important factor limiting crop growth and yield in the world. It can improve the ability to identify the occurrence and development of crop drought and to evaluate the degree of drought, and to take scientific measures to prevent drought and drought. The existing crop drought research is mainly focused on impact assessment, and qualitative analysis is the main, quantitative evaluation is less. Taking summer maize as an example, in 2014, 6 initial soil moisture gradients of continuous drought were carried out in the trilobal stage of summer maize. The variation of soil moisture and its effects on the water status of summer maize plants (stem, leaf moisture content, leaf gas exchange) and net photosynthetic rate (PN) were investigated. Transpiration rate (Tr) and stomatal conductance (GS), morphological characteristics (leaf area, plant height, biomass (root, stem, leaf and total dry weight), dry matter distribution (root to shoot ratio, leaf to stem ratio), growth stage. Yield formation and leaf characters (leaf area, leaf water content, leaf dry weight, leaf number) were weighed to determine the response of summer maize to soil water, and to reveal the process of drought occurrence and development of summer maize. The quantitative expression of drought intensity and drought degree was put forward. The main conclusions are as follows: 1) the water status of summer maize plants and the gas exchange parameters of leaves are mainly affected by the current soil water deficit, that is, drought intensity. However, the morphological characteristics and biomass of summer maize were mainly affected by accumulated water deficit, that is, drought degree. (2) normal total statistical tolerance method was used to determine the stem, leaf water content and transpiration rate of summer maize at seedling stage. Photosynthetic rate, stomatal conductance and leaf area of the critical soil with significant changes in relative humidity (0 ~ 30 cm) were 72%, 65% and 62%, respectively. 58% and 460.The drought occurrence and development process of summer maize were clarified: soil moisture deficiency directly affected stem moisture content and indirectly affected leaf water content through stem water content. Leaf water content will directly affect leaf photosynthesis and leaf area expansion, and its effect on individual level is the change of leaf area, and leaf area size will affect plant transpiration and radiation energy absorption. The quantitative expression of drought intensity based on crop water stress coefficient was proposed. The relationship between drought intensity and plant water and leaf gas exchange parameters was significant linear. Leaf gas exchange was more sensitive to drought than plant water, among which GsTrPn, stem moisture content, leaf moisture content, leaf moisture content and drought intensity were considered as the cumulative effects of drought duration. The quantitative expression of drought degree was put forward. The threshold index classification analysis method was used to collect the morphological characteristics (leaf area, plant height) and biomass (stem dry weight) of summer maize. Dry weight of leaves and total dry weight) the drought degree of summer maize can be divided into four grades, I. E. drought, light drought, moderate drought and heavy drought.) drought will affect the roots and stems of summer maize. The relative growth of leaves and the tradeoff growth of leaf characters (leaf area, leaf water content, leaf dry weight and leaf number) reflected the adaptability of summer maize to drought. With the increase of drought degree, summer maize preferred root growth. Summer maize can reduce leaf water content and leaf area to inhibit leaf metabolic activity and water loss, reduce growth rate and reduce growth consumption to maintain survival. The results showed that summer maize would adopt adaptive measures to reduce growth rate and increase resource storage to improve its viability.
【学位授予单位】：中国气象科学研究院
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S513;S423

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