Physiological response of turf grasses to trampling pressure.
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
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