新疆膜下滴灌超高产棉花根系构型的形成特征及调控机制研究

Cotton production of Xinjiang plays an important role in the development of China's cotton industry. With the agricultural structure adjustment, improve the yield per unit area to keep the total production is the fundamental way to achieve cotton production stability in Xinjiang, consequently, cotton security in China.In our preliminary experiment, root biomass and total plant biomass under root restriction decreased compared with the control. In contrast, aboveground biomass and yield under root restriction were considerably higher than the control. It showed that the tradeoff relationship between cotton root system simulation and yield could be broken, which could also provide a breakthrough for researching on physiological mechanism and regulation measure of high-efficient and high-yielding cotton. This project starts with the characteristic of root architecture in super-high-yielding cotton with drip irrigation under mulch. On the basis of definite cultivating super-high-yielding cotton (lint above 4 000 kgohm-2), configuration and dynamic formation of root architecture for super-high-yielding are studied. Furthermore, the evolution of index in root architecture during the process of yield enhancement and its relation with distribution rule of soil moisture and nutrients in root zone is analyzed. As a result, the change of root architecture and its regulating mechanism on canopy apparent photosynthesis, dry matter partitioning and senescing process in super high-yielding cotton are clarified. The architecture characteristic of "ideotype root" and its quantification index in different growth stage are proposed. We also attempt to find the regulation technologies which would achieve the cotton super-high-yielding through directive cultivated "ideotype root". The results can provide the theoretical basis for further excavation of root biology potential to improve cotton yield with drip irrigation under mulch. Additionally, the results abstained play an important theoretical and practical role in stabilizing Xinjiang cotton production.

新疆棉花生产在中国棉业发展中具有举足轻重的地位。随着农业产业结构调整，提高单产保总产是确保棉花安全的根本出路。我们前期研究发现，棉花根系生长受限条件下，根系生物量显著降低，但地上部生物量及产量均显著增加，表明根系构建和产量形成之间相互制约的权衡关系可以被打破。这为研究棉花高产高效的生理机制及调控途径提供了突破口。本项目从膜下滴灌超高产棉花根系构型特征入手，在定向培育超高产棉田（皮棉4000 kg hm-2）的基础上，研究超高产棉花根系构型特征及动态建成，分析产量提高过程中根系构型变化与根区水分养分分布的关系，阐明超高产条件下棉花根系构型和生理特征对光合生产、物质分配和衰老进程的调节机理，提出棉花超高产"理想根系"构型特征及其量化指标；探寻通过培育"理想根系"实现棉花超高产的调控技术。研究结果为充分挖掘棉花根系生物学潜力、提高单产奠定理论基础，同时对稳定新疆棉花生产具有重要的理论和实践意义。

作物高产稳产的基础是获得较高的生物产量，而生物产量的高低在很大程度上取决于根系的发育状况。本项目针对新疆棉区丰富的光热气候资源特点，立足膜下滴灌植棉的技术优势，从根系构型特征入手，在定向培育超高产棉田的基础上，研究了超高产棉花各生育时期的根系构型及活性的时空变化动态、产量提高过程中根系构型变化及与地上部生长的关系、主要栽培调控措施对高产棉花根系构型及根区水肥环境的调节等内容。取得的重要结果有：（1）分析了不同产量水平下棉花根系形态生理特征及与产量形成的关系，提出了超高产棉花根系构型呈“纵向延伸、功能强大”，即棉花中下层根系分布比例高、根系生理活性强，有利于促进地上部生长发育，降低根冠比，提高光合产物向棉铃的分配比例，增加铃重，进一步提高棉花产量；（2）以不同年代大面积种植的有代表性新陆早系列棉花品种为材料，探明了根系构型随着新陆早系列品种的更替呈现表层根量降低、深层根量增加和根系生理活性增强的趋势，明确了根系过氧化氢酶活性、硝酸还原酶活性以及根长密度可作为今后棉花高产品种选育的生理指标；（3）解析了合理水氮运筹有利于增加根质量密度、中下层根长密度和根体积密度，增强了根系活力，提高根系抗氧化保护酶系活性，从整体上能延缓根叶衰老，最终提高棉花产量和水分利用效率。（4）证实了通过增强土壤表层的根系分布和根系生理活性及深层根系生理活性，改善有效根长和光合生产的协调性，促进盛花期后干物质向生殖器官分配的基础上，降低非关键生育期植株无效水肥消耗，有利于增加棉花产量和水肥利用效率。在系统研究的基础上，确立了以培育“理想根系构型”为目标，通过综合集成棉花新品种及其配套栽培技术措施，构建了棉花超高产根系构型调控技术，以充分挖掘膜下滴灌棉花根系生物学潜力，提高绿洲棉田光热资源生产力，实现棉花高产高效。项目共发表文章9篇，其中SCI刊物7篇。大多数研究成果达到了国际先进水平。