High-resolution airborne hyperspectral and thermal imagery for early, detection of Verticillium wilt of olive using fluorescence, temperature and narrow-band spectral indices
High-resolution airborne hyperspectral and thermal imagery for early, detection of Verticillium wilt of olive using fluorescence, temperature and narrow-band spectral indices
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DOI：
10.1016/j.rse.2013.07.031
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发表时间：
2013-12-01
影响因子：
13.5
通讯作者：
Zarco-Tejada, P. J.
中科院分区：
文献类型：
--
作者：
Calderon, R.;Navas-Cortes, J. A.;Zarco-Tejada, P. J.
由土传真菌大丽黄萎病 (Verticillium dahliae Kleb) 引起的黄萎病 (VW) 是全球所有传统橄榄种植区中限制性最强的疾病。这种病原体定植于植物的维管系统，阻碍水流并最终引起水分胁迫。本研究探索了利用多光谱和高光谱图像计算的高分辨率热图像、叶绿素荧光、结构和生理指数（叶黄素、叶绿素 a + b、类胡萝卜素和蓝/绿/红 B/G/R 指数）作为 VW 感染引起的水压力和严重程度的早期指标。该研究是在两个自然感染大丽弧菌的橄榄园中进行的。机载热图像、多光谱图像和高光谱图像的时间序列是连续三年获取的，并且与飞行时的大众严重程度相关。在进行空传活动的同时，在叶子和树冠水平进行的现场测量显示，在 VW 严重程度范围内，树冠温度 (Tc) 减去气温 (Ta) 显着升高，叶子气孔导度 (G) 下降，从而在疾病的早期阶段识别出受 VW 感染的树木。现场测量的 Tc Ta 和 G 值越高，VW 严重程度越高。在叶水平上，VW 感染引起的 G 减少与光化学反射指数 (PRI570) 的显着增加和叶绿素荧光 (F) 的减少有关。机载飞行利用冠层图像衍生的机载 Tc Ta、根据热图像计算的作物水分胁迫指数 (CWSI)、蓝/蓝绿/蓝红比（B/BG/BR 指数）和叶绿素荧光，实现了 VW 的早期检测，证实了在现场获得的结果。在低 VW 严重程度下，空气传播的 Tc Ta 值显着增加 -2 K，并且与 G（R-2 = 0.76，P = 0.002）和 PRI570（R-2 = 0.51，P = 0.032）显着相关。疾病发展的早期阶段可以根据 VW 发展时 CWSI 的增加来区分，与 G 具有很强的相关性（R-2 = 0.83，P < 0.001）。同样，冠层叶绿素荧光在 VW 严重程度较高时下降，随着疾病进展而显着增加。这些结果表明了利用遥感技术早期检测大丽花弧菌感染和区分 VW 严重程度的潜力。基于冠温的指标（例如 CWSI）和可见比率 B/BG/BR 以及荧光可有效检测疾病发展早期阶段的 VW。在受影响的树木中，结构指数 PRI、叶绿素和类胡萝卜素指数以及 R/G 比是评估疾病造成的损害的良好指标。 2013 爱思唯尔公司。保留所有权利。
Verticillium wilt (VW) caused by the soil-borne fungus Verticillium dahliae Kleb, is the most limiting disease in all traditional olive-growing regions worldwide. This pathogen colonizes the vascular system of plants, blocking water flow and eventually inducing water stress. The present study explored the use of high-resolution thermal imagery, chlorophyll fluorescence, structural and physiological indices (xanthophyll, chlorophyll a + b, carotenoids and blue/green/red B/G/R indices) calculated from multispectral and hyperspectral imagery as early indicators of water stress caused by VW infection and severity. The study was conducted in two olive orchards naturally infected with V. dahliae. Time series of airborne thermal, multispectral and hyperspectral imagery was acquired in three consecutive years and related to VW severity at the time of the flights. Concurrently to the airborne campaigns, field measurements conducted at leaf and tree-crown levels showed a significant increase in crown temperature (Tc) minus air temperature (Ta) and a decrease in leaf stomatal conductance (G) across VW severity levels, identifying VW-infected trees at early stages of the disease. Higher Tc Ta and G values measured in the field were associated with higher VW severity levels. At leaf level, the reduction in G caused by VW infection was associated with a significant increase in the Photochemical Reflectance Index (PRI570) and a decrease in chlorophyll fluorescence (F). The airborne flights enabled the early detection of VW by using canopy-level image-derived airborne Tc Ta, Crop Water Stress Index (CWSI) calculated from the thermal imagery, blue/blue-green/blue-red ratios (B/BG/BR indices) and chlorophyll fluorescence, confirming the results obtained in the field. Airborne Tc Ta showed rising values with a significant increase of -2 K at low VW severity levels, and was significantly correlated with G (R-2 = 0.76, P = 0.002) and PRI570 (R-2 = 0.51, P = 0.032). Early stages of disease development could be differentiated based on a CWSI increase as VW developed, obtaining a strong correlation with G (R-2 = 0.83, P < 0.001). Likewise, the canopy-level chlorophyll fluorescence dropped at high VW severity levels, showing a significant increase as disease progressed. These results indicate the potentials of an early detection of V. dahliae infection and discrimination of VW severity levels using remote sensing. Indicators based on crown temperature such as CWSI, and visible ratios B/BG/BR as well as fluorescence were effective in detecting VW at early stages of disease development. In affected trees, the structural indices PRI, chlorophyll and carotenoid indices, and the R/G ratio were good indicators to assess the damage caused by the disease. 2013 Elsevier Inc. All rights reserved.