Shade responses of prostrate and upright turf-type bermudagrasses

Abstract

Bermudagrass (<italic>Cynodon dactylon</italic>) shade tolerance is a trait of immense importance to the turfgrass industry. However, little is known about shade tolerance of turf-type bermudagrass native to China. Additional knowledge of the mechanism of shade tolerance in bermudagrass is required to identify specific plant features that promote shade tolerance and assist breeding efforts worldwide. This study examines shade tolerance of two different bermudagrass cultivars, Yangjiang (prostrate form) and Guanzhong (upright form), which were developed in China. Each cultivar was subjected with 0, 30.4, 61.2, and 90.6% shade levels during growth and assessed for turf quality, turfgrass color intensity, biomass allocation, growth rate, antioxidant enzyme activity, leaf anatomy, and photochemical properties. Results generally demonstrated that turf quality and turf color intensity were lower in Guanzhong compared with Yangjiang on the 90.6% shade testing days. Yangjiang exhibited a less severe reduction of growth rate, leaf thickness, root to shoot ratio, and chlorophyll a to chlorophyll b ratio (Chl<italic>a</italic>/<italic>b</italic>) under 90.6% shade compared with Guanzhong. Both cultivars exhibited a decrease in photochemical efficiency as determined by reduced <italic>qP</italic>,<italic> ETR</italic>, and <italic>Fv/Fm</italic> values. Photochemical efficiency was impacted less in Yangjian, and superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) enzymes activities were greater than in Guanzhong when exposed to severe shade. When exposed to 90.6% shade level, Yangjiang had better turf quality than Guanzhong as determined by morphological, anatomical, and physiological features. Breeding efforts focused on these shade tolerance features will lead to improved bermudagrass germplasm and aid turf management in shade environments.