Physiological response of turf grasses to trampling pressure

Abstract

Some responses of turfgrasses to trampling stress were examined using simulated trampling methods in greenhouse and laboratory studies. Subsidiary experimental field studies indicated that the laboratory results were relevant to the natural situation. Shoot yield, 002 exchange and water relation parameters were measured, concentrating on the short term response to simulated trampling. A range of turf grass species and cultivars were included so comparison of wear tolerant and wear susceptible cultivar response was possible. An electrolyte release method was developed to ascertain plant injury following simulated trampling. Differences in injury index were related to levels of wear tolerance of the species and cultivars. Shoot yield was reduced with simulated trampling in all species and cultivars tested. Decrease in shoot yield correlated significantly with increasing intensity of trampling and increased injury index. Differences in amount of shoot decrease between species and cultivars related to ratings of wear tolerance in the literature. Net photosynthesis of Lolium perenne S23 decreased significantly with simulated trampling and a slight increase in respiration was recorded. Net photosynthesis correlated with injury level. Continuous monitoring over the initial few hours after treatment revealed a sharp decline in photosynthesis rates, followed by gradual recovery. Selected cultivars had a lower shoot water content two hours after treatment, the higher the intensity of simulated trampling the lower was the water content. SEM studies indicated disruption of epicuticular wax, therefore reducing cuticular resistance to water loss. Transpiration rates were reduced with simulated trampling and calculations showed a reduced hydraulic conductivity. These findings were related to relevant observations of response of plants to other stresses, particularly wind. A model is presented suggesting how observed and hypothetical responses, both short term and long term, may contribute to the survival or death of grass following trampling.