干旱胁迫对冬小麦冠层光谱及红边参数的影响

Effects of Drought Stress on Canopy Spectra and Red Edge Parameters of Winter Wheat

[目的]干旱是影响我国北方麦区的重要气象灾害之一。及时准确获取和掌握麦田干旱情况,对各级政府部门做出相应决策、采取积极有效的防旱、抗旱措施具有重要意义。作物冠层光谱分析是进行作物长势监测及灾害诊断的基础和有效手段,探索干旱胁迫下冠层光谱特征的变化规律,可为作物田间干旱遥感监测的展开提供先决条件。[方法]利用野外光谱测量仪对干旱胁迫下冬小麦冠层光谱进行采集,并对光谱特征及红边参数变化趋势进行分析。[结果]在可见光波段,光谱反射率为成熟期>灌浆期>抽穗期>开花期>拔节期>孕穗期;在近红外波段,光谱反射率为抽穗期>开花期>拔节期>孕穗期>灌浆期>成熟期。随着生育期的推进,红边幅值先增大后减小(max=0.0076,min=0.0013),红边位置先红移后蓝移(max=739 nm,min=700 nm),红边面积先增加后减小(max=0.31673,min=0.07069)。干旱胁迫越重,绿峰越不明显,红谷越浅,近红外平台越低;干旱胁迫越轻,绿峰越凸出,红谷越深,近红外平台越高。随着干旱胁迫程度的增大,红边幅值逐渐减小(max=0.008,min=0.00571)、红边位置逐渐蓝移(max=737 nm,min=727 nm)红边面积也逐渐减小(max=0.32065,min=0.24366)。[结论]研究结果可为实现快速、精准的农业干旱遥感监测提供参考及依据。

[Objective]Drought is an important meteorological factor affecting wheat production in northern China.It is of great significance to better understanding the drought sitation of wheat fields in a timely and accurate control manners,to provide scientific support for all levels of governments to make corresponding decisions on effective drought prevention.Crop canopy spectral analysis is a basic and effective method for crop growth monitoring and disaster diagnosis.Therefore,exploring the effects of drought stress on canopy spectral characteristics is of great significance for crop growth drought monitoring.[Methods]Field spectrum measurement instruments were used to collect winter wheat canopy spectra under drought stress,and the spectral characteristics and red edge parameter changes were analyzed.[Results]In the visible light range,a continuum of the highest to the lowest spectral reflectance were observed at maturing stage,filling stage,heading stage,flowering stage,jointing stage,and booting stage,in that order;while it was heading stage>flowering stage>jointing stage>booting stage>filling stage>maturing stage in the near infrared range.With the advance of the growth stages,the amplitude of the red edge was increased first and then decreased(max=0.0076,min=0.0013),and the position of the red edge first shifted to red and then to blue(max=739 nm,min=700 nm);the area of the red edge was increased first and then declined(max=0.31673,min=0.07069).The heavier the drought stress was,the less obvious the green peak was,and the shallower the red valley was with a lower near-infrared platform.On the contrary,the milder the drought stress was,the more green peaks were observed,and the deeper the red valley was with a higher near-infrared platform.The red edge amplitude was gradually decreased with the increase of drought stress levels(max=0.008,min=0.00571).The red edge position was steadily moved toward the blue edge with the increase of drought stress level(max=737 nm,min=727 nm),and the red edge area was declined with the increase of drought stress(max=0.32065,min=0.24366).[Conclusion]The results can provide reference and basis for realizing fast and accurate agricultural remote sensing drought monitoring.