陇东旱地冬小麦产量提高的同化物分配规律及其小花发育机制

In the context of attempting to substantially raise wheat yield potential, great attention of food production have been focused on how to understand the physiological and genetic basis of assimilation partitioning when there has been no systematic genetic progress in harvest index (HI) since the early 1990s. Consequently, field experiments will be designed by selecting different dryland winter cultivars released in different stages in Longdong semi-arid rainfed agricultural area. By means of defoliation, canopy shading and spikelet removal, systematical research will be aimed at investigating the variation characters of assimilation partitioning, floret development and ear photosynthesis. Research will also analyze deeply the intricate relationships among assimilation partitioning, floret development and ear photosynthesis and between those and yield determining factors (grain weight and seed number per ear). The objective of this study is to make clear the mechanisms of spike development and assimilation partitioning related to yield improvement of winter wheat cultivars planted in dryland. Yield improvement strategies of those cultivars will also be established from the views of cross combination, field selecting and management practice. Results will be an important theorical proof to enhance selecting efficiency of winter wheat in Longdong and even Northwest arid rainfed agricultural area. Moreover, it is also meaningful to deepen and broaden the physiological mechanism associated with yield potential improvement of winter wheat planted in dryland.

自上世纪90年代以来，通过增加收获指数的途径来提高小麦产量潜力的难度越来越大，主要原因是对小麦同化物分配的生理和遗传机制缺乏系统的认识。本项目拟在陇东旱地雨养农业区选择不同时期育成推广的冬小麦品种为研究对象，设置大田试验，采用剪叶、小穗移除、群体遮阴等方法人工改变源库关系，系统研究不同类型旱地冬小麦品种同化物累积分配、小花（原基）发育动态、穗部光合的变异规律，解析同化物分配、小花发育、穗部光合与产量构成要素（粒重和穗粒数）之间的内在联系，以期明确陇东旱地冬小麦品种产量提高的同化物分配规律和小花发育机制。从组合配置、田间选择、管理实践等方面提出陇东旱地冬小麦品种产量进一步提高的有效途径和今后改良的方向。研究结果将为陇东乃至西北旱地雨养农业区旱地冬小麦的高产、高效选育提供理论依据和技术途径，对深化和拓展旱地冬小麦产量潜力提高的生理机制有重要的理论和现实意义。

本研究选择在产量、株高、熟性上有较大差异且在不同年代推广的旱地冬小麦品种，人工改变源库关系，设置大田试验，系统研究旱地冬小麦穗花发育动态、同化物分配、穗部光合的品种间变异规律及其内在联系。研究结果表明，叶片和茎秆花后光合是旱地冬小麦籽粒增重的主要代谢源，芒和叶鞘等穗部光合贡献较小。植株全包（T2）、包穗（T3）、包穗下器官（T4）、包秆（T5）、剪芒（T6）、剪叶（T7）和剪叶和叶鞘（T8）穗粒重损失率分别为77.96%、41.88%、48.33%、27.27%、19.05%、37.30%、31.42%。川地矮秆品种籽粒增重更加依赖花后光合，旱地高秆品种“库”的转移能力更强，包穗（T3）和穗下器官（T4）使高秆品种穗粒重分别下降34.56%和40.30%；矮秆品种下降45.63%和62.37%。供试品种小花发育普遍经历“缓慢增加—快速增加—缓慢下降—快速下降（退化关键期）-缓慢下降”的过程，白齐麦、庆选15号、西峰24号、兰天25号、兰天26号、兰天30号、兰天48号、兰天52号、兰天54号等9个品种存在间隔期为5-7天的小花退化关键期，中麦175、兰天34、兰天36号、兰天42号、兰天43号等5个品种关键退化期为8-10天。旱地冬小麦同一品种不同穗位小花发育的进程基本一致，小穗退化主要发生在基部第一小穗，其次为顶部小穗，中部小穗发育最好，小花败育以基部和顶部小穗为主。同一小穗位基部小花发育最快，顶部最慢，败育主要发生在中上部小花。小花退化与单株穗干重、穗茎比、穗叶比、单株分蘖发育进程密切相关。小花发育期间，同一主穗不同的小花、同一植株不同的器官、主茎与分蘖之间均存在营养竞争，维持小花存活所需养分的首要对策是分蘖死亡，而不是茎秆和叶器官受限。最大小花分化数（F=3.32**）、小花存活率（F=2.63*）、小花结实率（F=2.82*）在品种间差异显著，变异范围分别为132.0～170.8个、35.59～46.85 %和32.02-39.13 %，穗花分化不足是早熟品种兰天42号和中麦175穗粒数低的主要原因。本研究结果为甘肃乃至西北旱地冬小麦高产栽培提供了理论依据，对深化和拓展旱地冬小麦产量潜力提高的生理机制有重要意义。