冬小麦干热风灾损评估模型研究

Dry-hot wind is one of the agricultural meteorological hazards frequently happens in the later growth stage of winter wheat in North China. It would severely reduce grain filling and lead grain yield fluctuation. However, quantitative yield reduction caused by dry-hot wind was unclear. And the regularity of dry-hot wind hazard is very important for agricultural meteorological hazard prevention and mitigation. Here, important winter wheat production base - Henan Province is selected to explore the regularity of dry-hot wind hazard and establish a yield reduction assessment model. Historical information as meteorology, crop observation, yield and hazard et al., will be collected. The spatial and temporal distribution regularity of hazard occurrence, variation trend and its influence will be studied. Hazard simulation experiments in field will be carried out, and the effects of different hazard intensities happen at different phase during wheat grain filling on dry matter accumulation and distribution, grain filling rate, photosynthetic rate, leaf water potential and 1000- kernel weight et al. will be investigated to explore the mechanism of the disaster formation. The series of historical yield will be decomposed to extract the yield loss caused by dry-hot wind, and indexes for loss assessing of the hazard will be built. The grain yield reduction assessment model caused by the dry-hot wind hazard will be built and validated in combination with mechanism analyses and mathematical statistics. Then the effects of different intensity of dry-hot wind happened in different phase of grain filling stage on winter wheat grain yield will be quantitatively evaluated. The results of this project will provide important reference of the situation of the disaster, impact assessment and emergency management for decision-making departments.

干热风是我国北方冬小麦生长后期最易发生的农业气象灾害之一，严重影响小麦灌浆攻籽和高产稳产。本项目针对我国干热风灾损定量评估研究较少、防灾减灾需求迫切的现状，以我国重要的冬小麦生产基地河南省为例，揭示干热风灾害的发生规律并构建灾损评估模型。项目拟通过收集历史气象、作物、产量及灾情资料，研究气候变暖背景下干热风灾害发生的时空分布特征、变化趋势及对冬小麦的影响规律；通过开展田间模拟试验，研究灾害不同发生强度和发生时间对冬小麦干物质积累与分配、灌浆速率、光合/蒸腾速率、叶片水势及千粒重等指标的影响，以探明干热风的致灾机理；分解历史产量资料序列，提取干热风产量灾损，并构建干热风灾害影响评估指标；机理分析与数理统计结合，建立干热风灾损评估模型并进行验证，量化评估冬小麦不同灌浆时期、不同强度的干热风灾害对最终产量的影响。本项目研究成果对于决策部门及时掌握灾情信息、开展灾害影响评估及应急管理有重要意义。

干热风对我国北方冬小麦灌浆有严重危害，但目前干热风灾害影响评估的研究成果较少，更缺乏开展灾损定量评估的模型和工具，远不能满足现代农业防灾减灾、保证粮食安全生产的需求。. 本项目充分利用河南省历史气象、产量、冬小麦发育期、麦田通量交换以及灾害控制试验等资料，在研究气候变暖后干热风灾害发生新特征的基础上，分析了干热风天气通量交换特征及对灌浆的影响，开展了基于产量灾损的灾害风险研究，构建了基于天气指数的干热风灾害影响评估指标，并建立了干热风灾损评估模型。.主要研究结论：. （1）上世纪90年以来冬小麦开花期显著提前，干热风最早发生日期则呈推后趋势，干热风对灌浆中后期危害的风险增高。. （2）干热风天气明显削弱小麦群体光合作用能力，小麦受到的胁迫越重，对CO2的同化时间越短。重干热风天气下的能量通量峰值大于轻干热风日，大于正常日，干热风灾害程度越重，蒸发比值越高。冬小麦日灌浆速度与部分时次CO2通量、能量通量显著相关。. （3）1981年以来河南省冬小麦干热风灾害平均减产率为7.4%，全省大部干热风灾害减产风险概率为20%-30%，许昌市南部、驻马店市大部地区等地，干热风产量灾损风险和气候风险均较高，是冬小麦灌浆期气象灾害的重点防范区。. （4）冬小麦灌浆中后期干热风灾害对产量有显著不利影响。干热风对冬小麦的胁迫随日最高气温的升高明显增大。构建的干热风对千粒重影响的评估模型通过了不同条件检验，模拟准确率在90%以上。. 研究成果为认清气候变化背景下干热风灾害的新特点、认清灾害发生规律、综合认识灾害风险和准确评估灾害损失提供了科学依据，对提高防灾减灾工作的针对性有重要意义。本项目构建的冬小麦干热风灾损评估模型克服了数理统计模型机理性不强、田间试验空间代表性不强的问题，兼顾了灾害影响机理、作物长势和数理方法，较单一方法开展影响评估具有更强的科学性和针对性。研究成果在“乡村专项”建设、农业气象决策服务等领域应用，取得了较好的服务效益。