Initiation of Unmanned Aerial System (UAS) Phenotyping of Plant Height and Canopy Width in Guar

Abstract

The use of the Unmanned Aerial System (UAS) has attracted scientific attention because of its potential to generate high-throughput phenotyping data. The application of UAS to guar phenotyping remains limited. Guar is multi-purpose legume species. India and Pakistan are the world ’s top guar producers. The U.S. is the world guar largest market with an import value of >$1 billion annually. The objective of this study was to test the feasibility of UAS phenotyping of plant height and canopy width in guar. The UAS data were collected from a field plot of 10 guar accessions on July 7, 2021, and September 27, 2021. The study was organized in a Randomized Complete Block Design (RCBD) with 3 blocks. A total of 23 Vegetation Indices (VIs) were computed. The analysis of variance showed significant genotypic effects on plant weight (p < 0.05) and canopy width (p < 0.05) during the first flight, and only on plant height (p < 0.05) during the second flight. Genotyping effects on most VIs were significant for both flights (p < 0.05). Normalized Difference Vegetation Index (NDVI) and Red Edge Normalized Difference Vegetation Index (NDRE) were significantly and highly correlated with plant height ( r = 0.74) and canopy width ( r = 0.68). The results will be of interest in developing high throughput phenotyping approach for guar breeding.