Water Consumption and Growth Rate of 11 Turfgrasses as Affected by Mowing Height, Irrigation Frequency, and Soil Moisture1

Abstract

AbstractWater availability and cost is a limiting factor in the growth of turfgrass under warm semi‐arid zone conditions. Methods of reducing water consumption of turfgrasses in these zones are of major importance.Water consumption and dry matter yield of clippings were determined for 11 turfgrass species or cultivars, 2 of which were cool season and 9 warm‐season types. The former belong to the C‐3 and the latter to the C‐4 group. The plants were grown in containers under typical summer conditions of the warm, semi‐arid zone. The growth rate of plants in the C‐3 groups was similar to that of those in the C4 group but their water consumption was higher. Amongst the C‐4 group, those plants with a sparse, vertical, growth habit, typical of forage crops, had a higher growth rate and water consumption than the dense, low growing ones. A significant correlation coefficient (r = 0.71 at p<0.05), was found between water consump tion and growth rate for the C‐4 plants.Delaying irrigation until the onset of temporary wilting, caused a significant decrease in water consumption and growth (up to 35%) in most gasses. Raising the clipping height from 3 cm to 6 cm for a period of 6 weeks led to increased vigor in all grasses as evidenced by growth rate, chlorophyll content and water consumption. This effect was continuous throughout the measurement period for the C‐3 types, but was temporary for the C‐4 types, declining again after 6 weeks.In experiments carried out under constant 34.5 C temperature, net photosynthesis of tall fescue (Festuca arundinacea Schreb. ‘Alta’) (C‐3) was only about one‐third that of C4 grasses although the evapotranspiration rate was equally high. The water uptake of the C4 type Zoysia matrella (L.) Merr. ceased at a much higher soil water potential than that observed for the C‐3 tall fescue and other C‐4 types. The decline of the rate of photosynthesis preceded the decrease in transpiration rate caused by the decreasing soil water potential.The most important single factor affecting water use was the carbon fixation pathway to which the grasses belonged. Whilst the choice of a species or cultivar of turfgrass is generally made on the basis of temperature adaptation, should the criterion be water consumption in relation to availability and cost, then C‐3 varieties should not be chosen for warm semi‐arid zones to the extent that is practiced now.