Kinetics of Hydrocarbon Induced Visual Green Color Loss on a Bermudagrass Green

Abstract

Core Ideas Kinetics models are essential to understanding complex dynamic processes.The kinetics of visual green color loss in turfgrass shoots is poorly understood.Kinetics of visual green color loss in turfgrass shoots in response to treatment with hydrocarbons was investigated.Rate and reaction order of visual green color loss in response to treatment with hydrocarbons were determined.Determining rate of and reaction order for visual green color loss increased understanding of color loss dynamics. Hydrocarbon machine fluids (MF) injure turf, inducing visual green color loss (VGCL) with onset of shoot necrosis. The dynamics of MF‐induced VGCL are unknown, having never been described. This research was conducted to increase understanding of color loss dynamics by investigating the kinetics of MF‐induced VGCL on a hybrid bermudagrass green (Cynodon dactylon [L.] Pers. var. dactylon × C. transvaalensis Burtt‐Davy). The effect six different MF had on changes in hue angle (θ) of shoots with time (t) was explained using digital image analysis (DIA) and curve fitting. Treating shoots with MF decreased mean θ from 88° at day zero to 33° at 12 d, as shoot color changed from green to brown. Fitting an exponential decay model of the form θ = θ0 + a0e‐kt to dθ/dt data revealed the rate of VGCL (−k) ranged from −4.45 d−1 (motor oil) to −0.16 d−1 (vegetable hydraulic oil) varying with MF (p < 0.01). Curve fitting also revealed dθ/dt was a first order reaction; plots of ln(θ − θ0) vs. t were linear (R2 = 1.0) for all six MF, while plots of zero order, half order, and second order reactions were not. Determining the rate of MF‐induced VGCL and its reaction order increased understanding of color loss dynamics by giving mathematical meaning to the processes. This was a step forward in understanding turfgrass injury behavior. The approach used for examining VGCL dynamics was inexpensive and nondestructive, and may be useful for other researchers studying plant color dynamics.