Heat and drought stress of common turfgrass species in a semi-arid environment

Date

2019-08

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Abstract

Residential irrigation in the summer months significantly burdens limited municipal water supplies, especially in semiarid regions. Bermudagrass (Cynodon spp. (L.) Pers), buffalograss (Buchloe dactyloides Nutt.), and zoysiagrass (Zoysia spp.) are common turf species chosen by homeowners in the transition zone of the United States (US). The objectives of this experiment were to evaluate common turf species to establish lawn irrigation recommendations for a semiarid environment. The NDVI reflectance measurements collected demonstrated differences in optimum irrigation requirements, indicative of plant vigor declining or plant reflectance maintenance throughout heat and drought stress. Visual turf quality were subjective measurements, but the presence of turf grass quality is ultimately the final objective.
‘Celebration’ Bermudagrass outperformed the other species in all three categories, as the more adapted and water efficient grass, while maintaining visual appeal and possessing less physiological signs of stress. ‘Legacy’ buffalograss demonstrated that water is often not the limiting factor from achieving a high visual turf quality or displaying extremely green and healthy leaves; the grass simply does not respond well to management. The zoysiagrass species performed commensurate to the irrigation level received but did not perform well with little or no supplemental irrigation. Greenhouse experiments were also conducted to evaluate the same cultivated varieties of turf species drought responses; specifically, physiological measurements under water deficit stress in a controlled environment. The focus of this research was physiological response changes in the turf overtime under controlled deficit irrigation. Average canopy temperature data was collected as an indirect physiological measurement as well as direct physiological measurements of transpiration rates, net photosynthesis (Pnet), dark respiration (Rd). Tall fescue ‘AT 1434’ was the most sensitive to water deficit stress in all greenhouse experiments, having reduced net photosynthetic rate (Pnet), and visual quality values. However, all varieties were stressed with heat equally as average canopy temperature values did fluctuate, but did not separate, and transpiration rates varied little indicative that water availability was the primary issue. If water was available, it was utilized rapidly to maintain energy balances and plant health. The dark respiration (Rd) rates had a lower negative magnitude for tall fescue as is expected, but all species Rd rates reduced after continued stress. Zoysiagrass species overall outperformed tall fescue. The zoysiagrass species performed commensurately to irrigation rates for many of the response variables, with ‘Jamur’ maintaining higher visual quality ratings in the field and ‘Zeon’ maintaining slightly higher visual quality ratings in the greenhouse experiment.

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Keywords

Drought stress, Deficit irrigation on turfgrass, Water use efficiency

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