春小麦花后高温早衰对氮肥运筹的响应机制研究

Spring wheat is one of the major crops in Ningxia plain. High temperature and drought disasters etc. caused by climate warming occur frequently in recent years. It leads to plant premature senescence and a significant reduction in yield and poor quality of spring wheat, which seriously affect the spring wheat production. Senium is always hot spots of crop physiology. It has great significance to study Physiological Mechanisms influenced by high temperature, the spring wheat premature senescence and yield in terms of enriching crop cultivation theory and achieving efficient production with high quality in wheat. For senescence study, it has more reports on blade senescence in different type winter wheat than that on root system, environment factors and the interaction with nitrogen. Methods of manual simulation associated with field trial were used in this project combining with enzymology and real-time fluorescent quantitative polymerase chain reaction (real-time PCR) and phytophysiology. Physiology and biochemistry mechanism of plant and root system premature senescence, photosynthetic character of senilism plant blade, active oxygen metabolism, vigor of root system, protected enzymatic activity, change regular pattern of hormone etc, photosynthate distribution, regularities of yield formation and their correlations were analyzed under high temperature.Regularities were detected for spring wheat premature senescence affected by high temperature. Using transcriptomics technique to find the related genes with spring wheat premature senescence and their different expression to reveale the physiology and biochemistry of permature senescence and nitrogen reduction harm caused by high temperature.Then, Agronomic measure that nitrogen relieve harm caused by high temperature were initially established and provide theoretical support for high efficiency and high quality spring wheat cultivation and breeding.

春小麦是宁夏平原的主要作物之一，近年来，气候变化引起高温干旱等灾害频发，导致春小麦植株早衰，产量下降，严重影响了春小麦生产；氮素是栽培因素中影响作物产量和品质最活跃的因素，研究氮肥运筹调控春小麦花后高温早衰的生理生化机理，对实现春小麦高产安全生产具有重大意义。本项目以春小麦为材料，盆栽和田间试验相结合，人工模拟高温，采用细胞学、酶学、转录组学（结合荧光定量PCR）、逆境生理学等方法，研究高温胁迫下春小麦早衰的分子机制及氮素调控机理，明确高温条件下不同施氮量、追氮时期和基追比、叶面喷施等氮肥运筹对植株叶片的光合特性、活性氧代谢、根系活力、氮代谢的变化规律及产量和品质形成规律，阐明氮素调控春小麦花后高温早衰的生理机制和基因表达，揭示高温引起春小麦早衰和氮素调控高温的分子机理，确定氮素缓解高温的合理运筹，为春小麦优质高效抗逆栽培提供理论依据。

气候变化引起高温干旱等灾害频发，导致春小麦植株早衰，产量下降，严重影响了其生产；本项目以春小麦为材料，研究了高温胁迫下春小麦早衰的分子机制及氮素调控机理，结果表明：高温出现时期越早对春小麦光合特性指标影响越大，同时导致春小麦膜脂过氧化程度加深，MDA以及超氧阴离子自由基在植株细胞内大量积累，同时显著降低了叶片保护酶类的活性，致使细胞膜透性增加，造成植株早衰现象。合理的施氮量能够延缓植株叶面积的衰退，并减弱旗叶叶绿素的下降速率，从而增加叶面积持续时间，降低叶绿素高值持续期，进而延缓春小麦旗叶的衰老，延长叶片的功能持续期；清除MDA和O2-对植物造成的损害；增加旗叶中叶片含氮量，提高Rubisco活性，有效的缓解高温胁迫；增加淀粉合成酶活性，提高千粒重和产量构成，增加单株穗粒数和千粒重，从而增加产量。在花后20天叶面喷施氮肥效果最好，其提高了小麦的捕光能力和逆境抵抗能力，增加了抗氧化能力、光合产物形成、ATPase和光系统Ⅰ/Ⅱ的活性，从而有效缓解高温带来的早衰现象，最终达到稳产的目的。追施拔节、抽穗肥能够延缓植株叶面积的衰老，减弱旗叶叶绿素的下降，延缓小麦旗叶的衰老，减缓高温对植株的危害。由此可知，科学的氮肥运筹可以有效缓减春小麦花后高温带来的早衰，从而降低由于干热风给生产带来的危害，本研究揭示合理的氮肥运筹缓减高温带来的早衰机制，同时提出切实可行的技术措施用于生产实践，保证春小麦的高产稳产具有重要的理论与实践意义。