Drought stress monitoring by laboratory and satellite spectral methods in an apple orchard

A Nagy,J Tamás,P Riczu

doi:10.31421/ijhs/20/1-2/1109

Abstract

An orchard can be examined on the basis of spectral data, using such methods with which the reflected radiation can be divided into a large number of (several hundreds) small spectral channel (some nm). Based on the spectral characteristics of the canopy, or the different index numbers calculated from hyperspectral data the water supply conditions of foliage can be well characterized. The research site is an intensive apple orchard, which located in Debrecen University, Centre for Agricultural and Applied Economic Sciences, Farm and Regional Research Institute at Pallag. During our experiments the evaluation of spectral, non-invasive measurement method are carried out for detecting stress symptoms caused by drought. Furthermore, MODIS NDVI time series data were analyzed for orchards situated in North-Eastern part of Hungary in drought effected and wet years in order to detect differences. Significant differences in NDVI values were detected after the end of June.

Highlights

Drought adaptation has a special significance in modern biomass production, in order to reduce production risks, to mitigate extreme water stress situations and to enhance food and crop safety
At 700 nm the reflectance increases steadily, and the leaves reflect the 60–80% of the light source energy between 700–1000 nm spectral ranges. It can be stated, that due to the noise of the measurements, but mainly to the thinness of the leaf samples, spectral differences are not observed in water sensitive 900–970 nm wavelength interval (Champagne et al 2001), it is not possible to calculate the well–known Water Band Index
Comparing the reflectance properties to dry material content of leaf samples significant correlation can be found at 540–575 nm (r~-0.610) as well as 750–830 nm (r~0.8) (Figure 2)

Summary

Introduction

Drought adaptation has a special significance in modern biomass production, in order to reduce production risks, to mitigate extreme water stress situations and to enhance food and crop safety. Healthy vegetation reflects the 40–50% of the incoming energy between 700–1300 nm spectral ranges due to the internal structure of the canopy, lignin content and parenchyma structure of the leaves (Gates et al, 1965). The measured reflectance plays an important role in distinguishing different plant species and possible water stress, even if these species are seems to be similar based on visible spectral range (Berke et al, 2004).

Results

Conclusion