The Effect of Exogenous Fructose On Creeping Bentgrass Heat Tolerance

Golf course putting greens are some of the most intensively managed areas of turf and are subjected to high stress through play and management practices. Creeping bentgrass (Agrostis stolonifera) is a popular choice amongst golf courses due to its high putting quality. However, in warmer climates, detrimental heat stress occurs, resulting in lowered photosynthetic efficiency and inadequate sugar production. An exogenous application of sugar in the form of fructose could potentially compensate for the lack of sugar being produced during heat stress. The objectives of this research were to determine if exogenous applications of fructose: 1) were taken up by the plant and, 2) produce measured physiological responses during heat stressed times. Field studies were conducted testing 2 types of fructose sources, a high fructose corn syrup and a pure fructose, ranging from 0.5%-8.0% mass/volume of sugar to water with a combination of surfactant. Field data collected included visual ratings, normalized difference vegetative index (NDVI) readings, and root measurement. Field results showed some phytotoxicity with high rates of fructose, while lower rates showed no visible damage compared to an untreated control. Low rates of surfactant resulted in very little phytotoxicity, while high surfactant rates showed damage, even at low fructose levels. Fructose had no positive effect on rooting, visual ratings, or NDVI readings. A surfactant study was then designed to measure the effect of various surfactants on fructose uptake. This study revealed that as hydrophilic to lipophilic balance increased, uptake of fructose increased. Surfactant concentrations were beneficial at 0.1 and 0.25% v/v, but higher rates reduced fructose uptake. Studies examining the uptake of radiolabeled fructose will also be discussed.