Inter-Relationships Between Canopy Features and Fruit Yield in Citrus as Detected by Airborne Multispectral Imagery
Inter-Relationships Between Canopy Features and Fruit Yield in Citrus as Detected by Airborne Multispectral Imagery
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DOI：
10.13031/2013.24371
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发表时间：
2008
影响因子：
1.5
通讯作者：
Xujun Ye;K. Sakai;S. Asada;A. Sasao
中科院分区：
文献类型：
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作者：
Xujun Ye;K. Sakai;S. Asada;A. Sasao
本研究旨在探讨柑橘冠层特征与果实产量之间的关系。温州蜜柑（Citrus unshiu Marc.），将生长在位于日本神奈川县Nebukawa农业研究站的果园中的东南亚本地柑橘品种用于该初步分析。在2002年和2003年的四个时间段，在红，绿色，蓝色和近红外（NIR）波段的高空间分辨率为0.2 ×0.2米的机载多光谱图像获得了超过实验场地。利用ERDAS Imagine 8.6软件生成基于归一化植被指数（NDVI）的图像。从这些图像中，阈值像素计数（TPC），在每个树冠中的几个叶类型的相对叶面积的指标，为48个选定的树样本提取使用MATLAB R12开发的程序。皮尔森相关分析，以检查之间的关系，每一个TPC和柑橘的果实产量在2002年，2003年和2004年。结果表明，一些TPC表现出更高的相关性，柑橘果实产量比那些对应于整个冠层大小，特别是从可见光的红色，绿色，蓝色波长提取的TPC。结果表明，营养生长前期（5月）成熟叶片的总蛋白含量与同一生长季的果实产量呈显著正相关，而营养生长前期（5月）幼叶的总蛋白含量与前一生长季和后一生长季的果实产量呈显著正相关。这些结果证实了冠层特征与柑橘产量之间的相互关系。这一信息也意味着一个不匹配的能量分配动态之间的不同叶类型的冠层，这可能会导致一个不同步的叶能量贡献，直接（成熟叶）或延迟（年轻的叶子），柑橘类作物的结果。此外，模型的基础上提取的TPC从早期的季节的图像证明了航空多光谱图像预测柑橘树的果实产量的潜力。所获得的产量估计可以提供有价值的信息，规划水果收获时间表，并生成处方地图，树木特定的管理措施，在个别树木的基础上。然而，在这些模型可以应用于实际情况之前，还需要进一步的调查。
The objective of this research was to examine the inter-relationships between canopy features and the fruit yield of citrus crops. Satsuma Mandarin (Citrus unshiu Marc.), a native citrus variety in southeastern Asia, grown in an orchard located at Nebukawa Agricultural Research Station, Kanagawa prefecture, Japan, was used for this preliminary analysis. Airborne multispectral images in the red, green, blue, and near-infrared (NIR) bands with a high spatial resolution of 0.2 ×0.2 m were acquired over the experimental site at four time periods in 2002 and 2003. Images based on normalized difference vegetation index (NDVI) were generated with ERDAS Imagine 8.6 software. From these images, thresholded pixel counts (TPCs), indicators of the relative leaf areas of several leaf types in each canopy, for 48 selected tree samples were extracted using a program developed in MATLAB R12. Pearson's correlation analysis was employed to examine the relationships between each of the TPCs and the fruit yields of citrus in 2002, 2003, and 2004. Results indicated that some TPCs showed a higher correlation with citrus fruit yield than those corresponding to the entire canopy size, particularly the TPCs extracted from the visible red, green, and blue wavelengths. The TPCs corresponding to the mature leaves before the fast vegetative growth (May) were found to be significantly correlated with the fruit yield of the same growing season, while those corresponding to the younger leaves during this period were more significantly correlated with the fruit yields of the previous and the following growing seasons. These results confirmed the inter-relationships between canopy features and the fruit yield of citrus crops. This information also implies an unmatched energy allocation dynamic between different leaf types within the canopy, which may lead to an unsynchronized leaf energy contribution, direct (mature leaves) or delayed (younger leaves), to the fruiting of citrus crops. In addition, the models based on the TPCs extracted from early season's images demonstrated the potential of airborne multispectral imagery to forecast the fruit yield of citrus trees. The obtained yield estimates can provide valuable information for planning fruit harvest schedules and generating prescription maps for tree-specific management practices on an individual tree basis. However, further investigations are necessary before these models can be applied in a practical situation.