TITLE:
Assessing Hyperspectral Vegetation Indices Responses of Six Pigweed Species
AUTHORS:
Reginald S. Fletcher
KEYWORDS:
Hyperspectral, Palmer Amaranth, Remote Sensing, Weeds
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.11 No.12,
December
14,
2020
ABSTRACT: Pigweeds (Amaranthus species), negatively impact crop production systems
throughout the world. They are distinguished from each other using manual
methods that are tedious and time-consuming to complete. Hyperspectral light
reflectance properties of plant leaves and canopies have shown promise for
detecting and mapping weeds in crop production systems. Vegetation indices
derived from hyperspectral reflectance data enhance differences between plants,
leading to better detection of them from other targets. The objective was to evaluate
the biomass and structural index, the biochemical index, the red edge index,
the water and moisture index, the light-use efficiency index, and the lignin
cellulose index for measuring differences among six pigweed species: Amaranthus albus (L), A. hybridus (L), A. palmeri (S. Wats.), A. retroflexus (L), A. spinosus (L), and A. tuberculatus [(Moq.) Sauer].
Two experiments were conducted under greenhouse conditions. Hyperspectral
reflectance measurements were collected from the plant canopies on two dates
for each experiment. Analysis of variance (ANOVA) and Tukey’s honest
significant difference (HSD) test were used to determine if statistical
differences (P ≤ 0.05)
existed among the pigweed
species canopies and to identify which species were statistically different for
a vegetation index, respectively. The ANOVA analysis detected statistical
differences among the canopy vegetation index values. Tukey’s HSD showed that
the biochemical index and the red edge index detected differences between two
to three pigweeds species on all dates of data collection. However, the
differences were date-specific. Furthermore, statistical differences were not
observed for all six species for any vegetation index. On the data collection
dates, A. albus and A. tuberculatus index values were statistically different from other pigweed species for one or
more of the vegetation indices. Future research should focus on using the
vegetation indices in combination with each other to measure differences
between the pigweed species and between them and other weeds and crops.