冬小麦干旱高光谱遥感监测机理及灾损评估研究

The drought problem of winter wheat has become the focus of attention of the government departments, and drought injury has a main effect on yield, based on the extreme climate change in recent years. So, the project is to analyze the impact of drought injury on winter wheat canopy spectral curve characteristics and its variation pattern at different growth stages, and seek the relationship between the different drought stress and spectral characteristics. The differences will be monitored using high spectrum resolving power technology at the time or before and after drought injury, and the changes of the physiological and ecological index will be analyzed. The relationship will be explored between winter wheat drought stress index and the variable quantity of the physiological and ecological index before and after drought stress. The relationship between drought stress index and yield will be elucidated though analyzing the relationship of physiological and ecological index, yield, and to realize the quantitative remote sensing monitoring of winter wheat drought injury. The physiological and ecological index will be analyzed in different growth stages by monitoring the high spectrum time series of winter wheat after drought injury, to identify the growth status and effect on the winter wheat growth. It can timely adjust the cultural practices and minimize food losses. The hyperspectral remote sensing information mechanism of winter wheat drought injury will be deeply understood through research to solve the problem of labor consuming and time consuming in monitoring winter wheat drought injury, and to improve timeliness of information acquisition, to strengthen the ability of understanding the process of winter wheat drought injury. And it will be expected to realize the real-time monitoring of winter wheat drought and drought analysis and yield assessment. It can provide the theoretical and strong technical support for the macro remote sensing accurately monitoring of winter wheat drought occurred, duration time, disaster strength and water-saving irrigation and other information.

针对近年来极端气候的变化，冬小麦日益严重的干旱问题已经成为政府部门关注的热点，对产量也造成了较大影响的问题，本项目分析旱害对冬小麦不同生育时期(尤其是对水分亏缺敏感时期)冠层高光谱曲线特征的影响极其变异规律，探求不同干旱胁迫与波谱特征之间的关系。结合高光谱遥感监测技术，分析冬小麦各生理生态指标的变化情况，探索干旱胁迫指数与各项生理生态指标在旱害发生前后变化量之间的关系，进而通过分析生理生态指标和产量的关系，以阐明干旱胁迫指数与产量的关系，实现旱害的定量遥感监测。同时进行冬小麦旱害的高光谱时序监测，对不同生育时期的生理生态指标进行相应的分析，辨别其生长状况，以及干旱对冬小麦后期生长的影响，以便适时调整栽培措施，使粮食损失最小化。通过研究加深对冬小麦旱害高光谱遥感信息机理的了解，提高信息获取的时效性，加强对冬小麦旱害过程认识的能力，为宏观遥感准确监测冬小麦干旱提供有力的技术支撑。

近年来在全球气候变暖的大背景下，极端天气的出现频率越来越高，程度也越来越深，干旱作为全球最为常见的自然灾害之一，严重影响到冬小麦生产。利用高光谱技术实现对干旱条件下的冬小麦长势特征及灾损评估具有重要的意义。项目执行期间，项目组严格按照计划任务设定执行，以冬小麦为研究对象，结合不同尺度上的水分池小区试验、大田试验和野外区域试验，利用高光谱技术为研究手段，开展了冬小麦干旱高光谱遥感监测机理及灾损评估研究，项目取得的主要进展和研究成果如下：.（1）不同干旱胁迫处理间冬小麦长势的各生理生化参数、光合参数、产量及产量性状和冠层高光谱存在显著差异，且冬小麦各生理生化参数与冠层高光谱存在较高的相关关系。冬小麦遭受干旱胁迫后，胁迫酶POD、SOD、MDA使植物在一定程度上对干旱胁迫进行忍耐、减缓或者抵抗。另外，研究证实红边区域（680-760 nm）能够敏感响应不同冬小麦作物水分。表明冠层高光谱与干旱冬小麦长势存在敏感的响应关系及利用冠层高光谱监测干旱冬小麦存在潜在的应用可行性。（2）对表征干旱胁迫冬小麦生理生化参数的光谱特征及光谱植被指数进行提取和确定，证实胁迫酶和光合参数与光谱波段：550、680-760、870、1150、1370nm，作物长势参数与光谱波段480、550、680-760、1120、1250 nm具有重要关系，探明植被指数RVI（531,687）在估算冬小麦水分含量方面表现最好，植被指数PVI和NDVI在反演土壤含水量和植株含水量方面效果最好；（3）构建和优化干旱胁迫下冬小麦生理生化参数、长势参数、籽粒产量及产量构成因素、籽粒品质和土壤理化性质的高光谱监测模型，实现了对干旱胁迫下冬小麦生长的高光谱监测；（4）构建综合长势指标（CGI），实现冬小麦长势的综合评估和高光谱监测以及对干旱胁迫下冬小麦的灾损分级及评估。（5）开展了常用植被指数的“光谱饱和”现象研究，探明了该现象的发生原因，并提出克服该现象的方法，为今后利用光谱植被指数应用于作物生长监测提供了理论依据。