长江中下游稻茬小麦高光效群体构建机理与调控途径研究

Yield-increasing potential of wheat following rice in the middle and lower Yangtze region is great due to water availability, high soil fertility, and adequate light. However, wheat production might be restricted by late maturity of rice, poor soil tillage quality, frequent natural disaster, and so on. This project will choose wheat varieties with good resistance in this region as test material, and will analyze the grain yield formation characteristics of high photosynthetic efficiency population with grain yield ≥9000kg/hm2 (HPEP) in wheat. The characteristics of the source and sink in HPEP will be studied from the structure configurations of leaf and non-leaf (stem, sheath and spike) source, the intensity and lasting duration of leaf photosynthetic function, as well as from the best configurations of the optimum number of spikes and the kernel weight. The characteristics of translocation will also be analyzed from the production and distribution of photosynthetic matter, the conversion efficiency from sucrose into starch. The diagnostic indices of the source, sink and translocation in HPEP will be suggested. This project will also definite the features of the fertilizer requirement for the HPEP and soil fertilizer supply during wheat growth. The feature of carbon assimilates exporting and partitioning and nigtrogen efficient utilization in HPEP will be ivestigated by using 13 C and 15N isotope. The cultivation approach to control vigorous growth, promote strong seedling and improve cold-hardiness before winter, strengthen stem and prevent lodging at the middle growth stage, and prevent premature senescence at the late stage will be suggested. It is beneficial to provide the theoretic basis and technical guide for improving wheat yield and output in the middle and lower Yangtze region.

长江中下游麦区温光水资源丰富、土壤肥力高，以稻茬小麦为主，由于稻茬小麦受前茬水稻成熟期迟、土壤耕种难、灾害频发等因素的制约，稻茬小麦产量潜力难以发挥。本项目选用小麦优良品种，重点研究：一、稻茬小麦高光效群体（子粒产量≥9000kg/hm2）产量形成特点；二、稻茬小麦高光效群体源库流特征，从叶源、非叶源（茎鞘源、穗源）的结构配置、功能强度与持续期和最佳穗数与穗粒重配置明确高光效群体的源库特征；从物质生产与输配、蔗糖源向库的运转与转化、库贮藏物的转化效率与持续期以及相关酶活性变化明确高光效群体的流特征；提出源库流协调的群体诊断指标；三、稻茬小麦土壤供肥和高光效群体的需肥特性；应用13C, 15N示踪分析高产群体碳高效输配与氮高效利用的生理基础；四、冬前控旺促壮提高抗寒能力、生育中期壮秆防倒、后期防早衰的高光效群体构建与调控技术途径，为提升长江中下游稻茬小麦生产能力提供理论与技术指导。

苏中地区属于长江中下游麦区，光、温、水等自然条件优越，但由于水稻茬口独特的生态环境和自然灾害等因素，稻茬小麦的产量始终不高不稳。目前作物的叶面积指数和经济系数已难以继续增加，若想进一步提高作物产量就必须提高生物量，因此，提高作物光能利用率成为关键。然而作物产量的形成是在一定空间和一定时间范同内综合光合能力的体现，在考虑光合能力的改善时，除进行叶片、植株生理机能和结构的改造外，还要从宏观上进行把握。本项目以生产中广泛应用且综合表现良好的小麦品种为试验材料，在苏中地区大田种植条件下，构建不同密度、施氮量及氮肥运筹组合下的稻茬小麦群体，从群体光能利用特征指标与产量之间的关系入手，开展产量与群体光合势、干物质积累、收获指数等群体指标之间的关系的研究，分析比较不同光效型稻茬小麦群体的光合生产能力、光合物质积累和转运的差异，探索建立稻茬小麦高光效群体特征体系，以期为苏中地区稻茬小麦高光效群体的构建及进一步栽培措施的调控提供参考依据。主要结论如下：一、探明了稻茬小麦高光效群体(子粒产量≥8000kg/hm2)产量形成特点，提出穗数，每穗粒数和千粒重需协调增加方可实现高产；二、研究了稻茬小麦高光效群体源库流特征，即库大，源足，流畅的特性；三、分析了稻茬小麦土壤供肥和高光效群体的需肥特性，同时应用15N示踪剖析高产群体碳高效输配与氮高效利用的生理基础，研究发现高产群体对肥料氮的吸收量和吸收比例显著高于低产群体，降低了肥料的淋溶损失。此外，高产群体在开花期和成熟期磷、钾的积累量也显著高于低产群体；四、冬前控旺促壮提高抗寒能力、生育中期壮秆防倒、后期防早衰的高光效群体构建与调控技术途径，为提升长江中下游稻茬小麦生产能力提供理论与技术指导。