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Article|08 Feb 2023|OPEN
Characteristics of photosynthesis and vertical canopy architecture of citrus trees under two labor-saving cultivation modes using unmanned aerial vehicle (UAV)-based LiDAR data in citrus orchards
Yuanyong Dian1,2 , Xiaoyang Liu1,2 , Lei Hu1,2 , Jinzhi Zhang1,3 , Chungen Hu1,3 , Yongzhong Liu1,3 , Jinxin Zhang1,3 , Wenbo Zhang1,3 , Qingqing Hu1,3 , Yahao Zhang1,2 , Yanni Fang1,3 , Jingjing Zhou,1,2 ,
1College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China
2Hubei Engineering Technology Research Center for Forestry Information, Wuhan 430070, China
3National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Wuhan 430070, China
*Corresponding author. E-mail: hupodingxiangyu@mail.hzau.edu.cn

Horticulture Research 10,
Article number: uhad018 (2023)
doi: https://doi.org/10.1093/hr/uhad018
Views: 423

Received: 12 Oct 2022
Accepted: 31 Jan 2023
Published online: 08 Feb 2023

Abstract

Analyzing and comparing the effects of labor-saving cultivation modes on photosynthesis, as well as studying their vertical canopy architecture, can improve the tree structure of high-quality and high-yield citrus and selection of labor-saving cultivation modes. The photosynthesis of 1080 leaves of two labor-saving cultivation modes (wide-row and narrow-plant mode and fenced mode) comparing with the traditional mode were measured, and nitrogen content of all leaves and photosynthetic nitrogen use efficiency (PNUE) were determined. Unmanned aerial vehicle (UAV)-based light detection and ranging (LiDAR) data were used to assess the vertical architecture of three citrus cultivation modes. Results showed that for the wide-row and narrow-plant and traditional modes leaf photosynthetic CO2 assimilation rate, stomatal conductance, and transpiration rate of the upper layer were significantly higher than those of the middle layer, and values of the middle layer were markedly higher than those of the lower layer. In the fenced mode, a significant difference in photosynthetic factors between the upper and middle layers was not observed. A vertical canopy distribution had a more significant effect on PNUE in the traditional mode. Leaves in the fenced mode had distinct photosynthetic advantages and higher PNUE. UAV-based LiDAR data effectively revealed the differences in the vertical canopy architecture of citrus trees by enabling calculating the density and height percentile of the LiDAR point cloud. The point cloud densities of three cultivation modes were significantly different for all LiDAR density slices, especially at higher canopy heights. The labor-saving modes, particularly the fenced mode, had significantly higher height percentile data.