小麦小孢子发育期弱光胁迫降低穗粒数的过程及机理研究

Due to a developing industry, haze weather phenomenons lead to more and more serious in decreasing light intensity and sunshine hours in North China Plain. Wheat growth and development are seriously threatened. It is very important for grain yield to improve grain number for winter wheat. In order to investigate how shading affects grain number during young microspore stage of winter wheat, the shading study will be conducted in fields and as well as pot experiments with cultivars of different shading tolerant. Shading stress is applied on the plants with varying light intensity using horizontal shading net at young microspore stage. Young microspore stage is the period most sensitive toward shading stress in grain number level. An auricle distance (AD) measurement scale is established to estimate pollen developmental stage and young microspore stage.. Based on the statistical analysis of grain number per mainly spike under shading at young microspore stage of winter wheat, the mainly changes characteristics of shading at young microspore stage on grain number of different shading tolerant cultivars will be initially stated. According to grain numbers of reciprocal crossing, sugar metabolism, microscopic observations and cytology characters of young microspore stage and study on anther and ovary development of winter wheat under shading stress, Physiological mechanism of shading causing abortion of pollen development and abortion of pollen development leading to reduced grain number during young microspores stage will be initially clarified. The project will provide theoretical basis for guaranteeing food safety in China.

工业发展、阴霾天气增多使我国华北地区光照强度下降，日照时数减少，小麦生长发育受到弱光严重威胁。小麦穗粒数对产量至关重要。为深入揭示弱光下小孢子发育进程和对穗粒数的影响机制，本研究以耐弱光和光敏感小麦为材料，以对穗粒数变化最敏感的小孢子发育期为研究阶段，利用小麦主茎AD值标记小孢子发育进程，在田间和桶栽人工模拟不同弱光强度下穗粒数变化研究。通过统计分析不同品种在弱光条件下主茎穗粒数的差异，初步明确不同耐弱光品种在小孢子发育期弱光后穗粒数变化规律；通过弱光后正反交穗粒数差异、弱光下小孢子发育过程、子房和花药发育过程的细胞学分析以及糖代谢分析，初步阐明弱光后花粉败育以及穗粒数降低的调控机制。为雾霾条件下我国粮食安全提供理论基础。

工业发展、阴霾天气增多使我国华北地区光照强度下降，日照时数减少，小麦生长发育受到弱光严重威胁。小麦穗粒数对产量至关重要。为深入揭示弱光下小孢子发育进程和对穗粒数的影响机制，本研究以不同的耐弱光和光敏感小麦品种为材料，以对穗粒数变化最敏感的小孢子发育期为研究阶段，利用小麦主茎AD值标记小孢子发育进程，在田间和桶栽人工模拟不同弱光强度下（遮荫98%，60%），研究小麦小孢子发育期遮荫胁迫对小麦主茎穗粒数的影响，干物质积累与分配的差异，花粉发育的细胞学分析以及遮荫胁迫后保护酶、光合特性、荧光特性等形态和生理特性的影响。通过统计分析不同品种在弱光条件下主茎穗粒数的差异以及调控机制。研究结果表明，不同品种小孢子发育时期的AD值不同。不同品种在小孢子发育期持续不同天数的重度遮荫（98%）胁迫后，产量都显著下降。主茎穗粒数显著降低是小麦品种间产量造成差异的主要原因。小孢子发育期遮荫胁迫后小麦的株高、穗长、生物量、小花数显著降低，叶片最大净光合速率、气孔导度、叶片中糖含量都有不同程度的下降趋势，分蘖数却有不同程度的增加。暗示着光合产物降低，糖运输受阻，养分供应不足，导致花药和子房发育受到不同程度的影响，最终导致了花粉育性降低，穗粒数降低。但不同小麦品种存在显著差异。与对照相比，光敏感品种科农9204和良星99产量降低了74.9%和91.4%；耐荫型品种河农825和冀麦32的产量降低了17.3%和14.2%。耐荫型小麦由于胁迫解除后光合速率能迅速恢复，能迅速产生分蘖并形成籽粒，所以对产量有一定补偿作用。但无论是否耐遮荫品种，应对弱光的策略都是迅速产生分蘖，补偿穗粒数的降低。光敏感小麦品种，分蘖虽能迅速产生，并抽穗，但补偿能力有限，无效分蘖较多。本研究对鉴选和培育耐荫小麦品种提供重要信息。