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Monitor of apple tree growth status based on spectral technology

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Paper number  131596269,  2013 Kansas City, Missouri, July 21 - July 24, 2013. (doi: @2013
Authors:   Xiaolei Deng, Minzan Li, Lihua Zheng, Yao Zhang
Keywords:   reflectance apple flowers and leafs nitrogen environmental parameters apple tree growth status.

Abstract. Spectral technology is one of the nondestructive approaches to estimate plant nitrogen status. The objective of this study is to monitor the apple tree growth status based on spectra technology in the orchards. The experiments were carried out in a Red Fuji apple orchard in Beijing. Flower/leaf samples from 15 year-on trees and 5 year-off trees were collected. The average parameters of the samples gathered from different parts of an apple tree were calculated to find the distributions of the nitrogen in the tree. The reflectance spectra of flowers/leaves from three parts (base, middle, top) of each main branch were measured. The growth environmental parameters such as the environmental temperature and humidity, the light intensity, and the leaf areas were also recorded. These could assistant us in monitor the apple tree growth status. The results showed that the correlation between the first deviation for reflectance of apple flowers and nitrogen content reached the maximum at wavelength 1201 nm. It was higher than that between the original reflectance and nitrogen content. The reflectance spectra of apple trees changed significantly at different stages. Leaves from the top of the branch had higher reflectance than the other parts of the branch. The adjusted R2 of the linear regression models for predicting leaf nitrogen content by using the combination of reflectance at 712 nm and 800 nm could reach to 0.482 while the RMSE was 0.238 (n=55).

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