TITLE:
Spectral Discrimination of Two Pigweeds from Cotton with Different Leaf Colors
AUTHORS:
Reginald S. Fletcher, Krishna N. Reddy, Rickie B. Turley
KEYWORDS:
Pigweeds, Cotton Near-Isogenic Lines, Leaf Reflectance
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.7 No.15,
October
28,
2016
ABSTRACT: To implement strategies to control Palmer amaranth (Amaranthus palmeri S. Wats.)
and redroot pigweed (Amaranthus retroflexus L.) infestations in cotton (Gossypium
hirsutum L.) production systems, managers need effective techniques to identify the
weeds. Leaf light reflectance measurements have shown promise as a tool to distinguish
crops from weeds. Studies have targeted plants with green leaves. This study
focused on using leaf hyperspectral reflectance data to develop spectral profiles of
Palmer amaranth, redroot pigweed, and cotton and to determine regions of the light
spectrum most sensitive for pigweed and cotton discrimination. The study focused
on cotton near-isogenic lines created to have bronze, green, or yellow colored leaves.
Reflectance measurements within the 400 to 2500 nm spectral range were obtained
from cotton and weed plants grown in a greenhouse in 2015 and 2016. Two scenarios
were evaluated for the comparison: (1) Palmer amaranth versus cotton lines and (2)
redroot pigweed versus cotton lines. Statistical significance (p ≤ 0.05) was determined
with analysis of variance (ANOVA) and Dunnett’s test. Sensitivity measurements
were tabulated to determine the optimal region of the light spectrum for weed
and cotton line discrimination. Optimal bands for weed and cotton separation were
600 to 700 nm (both weeds versus cotton bronze and cotton yellow), 710 nm (Palmer
amaranth versus cotton green), and 1460 nm (redroot pigweed versus cotton green).
Spectral bands were identified for separating Palmer amaranth and redroot pigweed
from cotton lines with bronze, green, and yellow leaves. Ground-based and airborne
sensors can be tuned into the regions of spectrum identified, facilitating using remote
sensing technology for Palmer amaranth and redroot pigweed identification in
cotton production systems.