UAV-based multispectral vegetation indices for assessing the interactive effects of water and nitrogen in irrigated horticultural crops production under tropical sub-humid conditions: A case of African eggplant
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Date
2022
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
UAV-based multispectral vegetation indices are often used to assess crop performance and water consumptive
use. However, their ability to assess the interaction between water, especially deficit irrigation, and nitrogen
application rates in irrigated agriculture has been less explored. Understanding the effect of water-nitrogen in teractions on vegetation indices could further support optimal water and N management. Therefore, this study
used a split plot design with water being the main factor and N being the sub-factor. African eggplants were drip
irrigated at 100% (I100), 80% (I80) or 60% (I60) of the crop water requirements and received 100% (F100), 75%
(F75), 50% (F50) or 0% (F0) of the crop N requirements. Results showed that the transformed difference
vegetation index (TDVI) was best in distinguishing differences in leaf moisture content (LMC) during the
vegetative stage irrespective of the N treatment. The green normalized difference vegetation index (GNDVI)
worked well to distinguish leaf N during vegetative and full vegetative stages. However, the detection of the
interactive effect of water and N on crop performance required a combination of GNDVI, NDVI and OSAVI across
both stages as each of these 3 VI showed an ability to detect some but not all treatments. The fact that a certain
amount of irrigation water can optimize the efficiency of N uptake by the plant is an important criterion to
consider in developing crop specific VI based decision trees for crop performance assessments and yield
prediction.
Description
Journal Article
Keywords
Water use efficiency, Nitrogen use efficiency, UAV, Irrigation, Water stress, Vegetation indices