苹果花期冠层光谱探测的规范化技术方法探讨

Standardization of Technical Methods for Apple Florescence Canopy Spectral Detection

2008年和2009年,针对苹果花期冠层光谱进行了不同天气条件、不同探测时间、不同探头高度、不同探测角度条件下的冠层反射光谱探测试验,分析其对苹果花期冠层光谱特性的影响,探索规范化的光谱探测技术方法。结果表明,苹果花期冠层在不同条件下的反射光谱响应呈现出一定的规律性,特别是在760～1350nm近红外波段表现尤为明显。研究发现,随着光照强度的减弱,冠层光谱反射率降低,在晴天和少云时探测冠层光谱较理想;风速在2级以下时,冠层光谱较稳定;在10:00～15:00测定冠层光谱差异较小;探测高度以整个苹果树冠层充满光谱仪探头视场时光谱曲线较稳定;探头以垂直或近似垂直观测为最佳。在此基础上,提出了苹果花期冠层光谱探测的规范化技术方法,为苹果冠层光谱探测及信息提取提供了科学依据。

Aiming at spectral detection of apple florescence canopy,the present paper carried out spectral detection tests under different weather conditions,different detection times,and different detection heights and angles to apple canopy in the two years of 2008 and 2009,so as to analyze impacts of these factors on apple canopy spectral characteristics and explore standardized spectral detection methods for apple florescence canopy.The results indicated the regularity in spectral reflectance of apple florescence canopy to a certain degree under different conditions,especially in the 760-1 350 nm near-infrared bands.The authors found that canopy spectral reflectance declined along with the decrease in sunshine and it is appropriate to detect canopy spectrum in sunny days with few clouds.In addition,spectral reflectance tended to be stable when the wind scale was below grade 2.The discrepancy of canopy spectra is small during the time period from 10：00 to 15：00 of a day compared to that of other times.For maintaining stable spectral curves,the height of detector to apple canopy needed to be adjusted to cover the whole canopy within the field of view according to detection angle of the detector.The vertical or approximately vertical detection was the best for canopy spectral reflectance acquisition.The standardization of technical methods of spectral detection for apple florescence canopy was proposed accordingly,which provided theoretical references for spectral detection and information extraction of apple tree canopy.