Temperature Impact On Secondary Metabolite Development in Turfgrasses.

Secondary metabolites are compounds which influence plant response to stressful environments. There are numerous compounds that are broadly classified as carotenoidsoranthocyanins. These compounds are considered important in plant response to stresses such as high light intensity, increased UV-B incidence and possiblly to drought tolerance. Their role in turfgrasses is not well understood and further work into their production in response to specific stresses is warranted.. Creeping bentgrass (Agrostis stolonifera) cultivars ‘L-93’ and ‘Penncross’, Tall fescue (Festuca arundinicea) ‘Barvado’ and Bermudagrass (Cynodon dactylon) ‘Transcontinental’ were planted in 11cm diameter pots with 80/20 w/v sand/peat mix and propagated with sufficient irrigation and fertilization to prevent nutrient or water stress. These commonly used C₃ and C₄ turfgrasses were subjected to three temperature levels. Standard greenhouse temperature ~20 °C and light intensities of ~ 800 μmol m^-2 s^-1, 10 °C and 2 °C in light intensities of ~600 μmol m^-2 s^-1. The development of anthocyanins and carotenoids was measured over time scales of 0, 6, 12, 24 and 48 hrs. Samples grown at room temperature and 10 °C showed greater variability in anthocyanin content while samples treated in 2 °C produced a rapid response to the temperature change. In warmer temperatures without light, all grasses produced higher levels of anthocyanins while when light intensity increased and temperature decreased there was a significant drop in anthocyanin quantities in turfgrasses grown 2 °C. Bermudagrass produced the lowest levels of anthocyanins but showed the greatest response to temperature. Total carotenoids were highest in Bermudagrass but the response to changes in temperature varied. In cooler temperatures with light there was a greater decrease in carotenoid content in C₃ turfgrass plants. The results indicate that turfgrasses respond differently to temperature changes and also indicates potential for understanding damage in higher light conditions and cooler temperatures to turfgrass plants.