基于群体茎秆临界弯矩的小麦抗倒伏风速预测理论模型

The lodging is a phenomenon that wheat stalk is from its natural upright position to the permanent displacement caused by the interaction of the wind, rain and plant stalks characteristics. Wheat all may produce lodging from the anthesis stage to fully mature. Every year in China, the grain loss caused by lodging can reach 2 million tons. Due to the limitation of the research method, the current researches on the wheat lodging resistance evaluation and the lodging mechanism are based on a single stem, and the results of the evaluation are mainly qualitative. Therefore, the study on wheat population lodging resistant mechanism and the rapid quantitative evaluation theory model for the population lodging resistant characteristics is a key problem to be solved urgently in super high yield wheat breeding and the field production. The objectives of this project are, on the basis of study on the microscale wind speed characteristics of the distance ground height 10 meters below in the wheat fields, to make use our invention lodging-resistance electronic tester and wind tunnel as the research method to clarify the relationship between the wheat plant morphological anatomy, population height, density and other plant internal characteristics and the population lodging-resistance and the mechanism of action, to provide reliable screening index system for lodging resistant super high yield wheat breeding, and eventually to establish a wheat population lodging-resistance wind speed forecasting theory model based on their stalks maximum bending moment and the microscale wind speed, wind pressure conversion relationship to provide theoretical basis for super high yield wheat lodging resistance evaluation. This model not only can quickly and accurately predict the maximum wind speed that wheat population can withstand when wheat lodging has not occurred, but also forecast the wheat varieties' lodging resistant probability according to the wind speed distribution in history data, and provide theoretical guidance for super high yield wheat breeding and the field production.

小麦倒伏是由风、雨及植物茎秆特性等内外因素相互作用所引发的使植株茎秆从自然直立状态到永久错位的现象。小麦自杨花期至完全成熟均可产生倒伏，每年我国因倒伏造成的粮食损失可达200万吨。因此，深入研究小麦群体倒伏机制，建立快速、定量的小麦群体抗倒伏风速预测理论模型是超高产小麦选育及生产中急需解决的关键问题。本项目的研究目标是在对田间近地微尺度风速变化特性研究的基础上，利用我们发明的抗倒伏测定仪和风洞为主要研究手段，阐明小麦植株形态解剖学以及群体高度、密度等植物内在特性与群体抗倒伏关系及作用机制，为抗倒伏超高产小麦选育提供可靠的筛选指标体系；建立基于小麦群体茎秆临界弯矩及近地微尺度风速的小麦群体抗倒伏风速预测理论模型，为抗倒伏超高产小麦评价提供理论依据。该模型不仅可以在未发生倒伏的自然条件下快速、准确地预测小麦群体能够承受的最大风速，并可依据地区历史风速分布信息预测供试小麦品种发生倒伏的机率。

为构建小麦群体抗倒伏临界风速计算模型，本项目对小麦倒伏小麦倒伏类型、小麦倒伏与环境内外因素关系、小麦田间近地面层风速特性及对小麦倒伏的影响进行了研究。结果表明，目前中国小麦生产中发生的大面积倒伏主要包括大风型、持续降雨型和大风强降雨型三种类型，分别占样本总数的8%、19%和73%。小麦倒伏严重程度与小麦自身的抗倒伏能力及环境风速和降雨量密切相关。小麦茎秆强度是决定倒伏的内部因素，大风及降雨则是导致倒伏的外部因素。刮风及降雨施加在小麦茎秆上的弯矩超过其茎秆的破坏弯矩是引发倒伏的根本原因。田间近地面层风速廓线符合对数或指数特性，R=0.969。田间小麦表观粗糙度主要受风速影响，是风速的指数函数。田间近地面层风攻角具有明显的日变化性，并随距地面高度的降低而逐步增大。小麦群体抗倒伏推力与小麦抗倒伏临界风速呈显著相关关系，依据小麦群体抗倒伏推力、表面粗糙度、透风系数及风攻角计算小麦群体抗倒伏临界风速，可以消除利用单一或少数指标评价小麦抗倒伏能力所存在的偏差；结果可靠，方法简单，可以用于小麦抗倒伏性评价、小麦品种推广区域选择以及田间倒伏因素评价研究等。