冬小麦冻害高光谱遥感监测机理研究

The frequency of winter wheat freeze injury is becoming higher and higher, and freeze 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 freeze injury on winter wheat canopy spectral curve characteristics and its variation pattern, and seek the quantitative relationship between the different temperature and spectral characteristics. The differences will be monitored using high spectrum resolving power technology before and after freeze injury, and the changes of the physiological and ecological index will be analyzed. The relationship will be explored between winter wheat growth recovery rate and the variable quantity of the physiological and ecological index before and after freeze injury. The relationship between growth recovery rate and yield will be elucidated though analyzing therelationship of physiological and ecological index and yield，and to realize the quantitative remote sensing monitoring of winter wheat freeze injury. The physiological and ecological index will be analyzed in different growth stages by monitoring the hige spectrum time series of winter wheat after freeze 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 freeze injury will be deeply understanded through research to solve the problem of labour consuming and time consuming in monitoring winter wheat freeze injury, and to improve the timeliness of information acquisition, to strengthen the ability of understanding the process of winter wheat freeze injury. It can provide the strong technical support for the disaster prevention and disaster reduction of winter wheat production.

"针对近年来极端气候的变化，冬小麦冻害的发生频率越来越高，对产量也造成了较大影响的问题。因此本项目分析冻害对冬小麦冠层高光谱曲线特征的影响及其变异规律，探求不同温度与波谱特征的定量关系。利用高光谱遥感技术监测冻害发生前后植被指数的差异，分析冻害前后冬小麦各生理生态指标的变化情况，探索冬小麦生长恢复度与各项生理生态指标在冻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，阐明生长恢复度与产量的关系，以实现冻害的定量遥感监测。同时，进行冬小麦冻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，以及冻害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冻害高光谱遥感信息机理的了解，解决冬小麦冻害监测耗工耗时的问题，提高信息获取的时效性，加强对冬小麦冻害过程认识的能力，为冬小麦生产的防灾、减灾决策提供有力的技术支撑。

本研究开展了冻害前后冬小麦各生理生态指标的动态变化情况的研究，叶绿素含量、类胡萝卜素和植株含水量均有所降低，并随着胁迫处理温度的降低和时间的延长，其损失程度更加严重。叶面积指数与生物量虽然随着植株发育的健全逐步升高，但同一时期下，随着低温胁迫程度加深，其降低程度更加明显。低温胁迫后，冬小麦功能叶的POD活性变化总体趋势与对照组相同，但强冬性品种的抗寒性较强，而半冬性品种恢复能力较强。SOD保护系统对胁迫时间的敏感程度高于胁迫温度；MDA积累量没有表现出明显变化。MDA积累量较低可能是由于低温胁迫造成植株晚熟带来的结果，POD、SOD使植物在一定程度上对低温胁迫进行忍耐、减缓或者抵抗；开展了冻害对冬小麦冠层高光谱曲线特征的影响极其变异规律，探明了拔节期冬小麦在遭受低温胁迫以后，冠层光谱对其响应敏感，红边位置随低温胁迫的加剧出现“蓝移”现象；在上述研究的基础上建立了冬小麦冻害后生理生态指标的监测模型，并以此为依据构建了冬小麦生理生态指标冻害监测体系；开展了冬小麦大田实际降温降雪试验，对其光谱特征进行了研究，与前期盆栽试验研究结果相似，即小麦冠层光谱反射率明显低于冻害前，近红波段差异较明显，整体反射率下降，针对冬小麦光谱曲线变化，提出了应用冻害前后的光谱特征变化幅度的概念来表征冻害严重程度；开展了山西省闻喜县冬小麦农田生态区域冻害研究，结合地面光谱研究，从已处理的HJ卫星影像上提取6种植被指数（RVI、DVI、NDVI、EVI、GRVI、SIPI），对不同时相遥感数据分别运用变化向量分析、冻害表征植被指数及综合方法来确定冬小麦是否遭受冻害及冻害严重程度与恢复程度，确定其等级，并定量分析冻害对产量的影响。