Research Update

Silicon Impacts on Summer Stress Tolerance of Creeping Bentgrass Putting Greens

Authors: Xunzhang Zhang, Ph.D., Rose Harvey, Ben Goddard, Mike Goatley, Ph.D., Travis Roberson, Isabel Brown, and Kelly Kosiarski School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA

Heat and drought stress greatly reduce quality of creeping bentgrass putting greens during the summer months in U.S. transition zone. To improve putting green performance, golf course superintendents have used various cultural practices and chemical products, including biostimulants. Plant biostimulants have been used to improve stress tolerance and quality of turfgrasses. Silicon (Si) is naturally absorbed by plants from soil as monosilicic acid, Si(OH)4. Although Si is not considered to be an essential macronutrient, the content of Si in some plants can be in the range of certain macronutrients. These Si deposits are commonly found where their presence acts as a surfacearea defense system (on leaf and stem hairs, and on the outer epidermal walls) which benefits plant tolerance to drought. Silicon is also considered as a biostimulant, influencing plant physiological fitness under abiotic stress. Our previous study in growth chamber indicated that foliar application of Si improved creeping bentgrass heat and drought stress tolerance. The objective of this study was to evaluate effects of Si on physiological fitness and performance of creeping bentgrass putting greens during summer stress.

We conducted a field study at Virginia Tech Turfgrass Research Center, Blacksburg, in 2022. There were three treatments, including untreated control, potassium silicate (containing 4.7% silica) from Harrell’s at 3 fl. oz/1000 ft2 biweekly and potassium silicate at 6 fl. oz/1000 ft2 applied biweekly beginning June 8 and ending August 31. Plot size was 5 x 6 ft. A randomized block design with four replications was used. Regular fertilization and mowing were performed. The plots were subjected to two dry-down cycles from June 21 to June 30, and from July 11 to 20 by withholding irrigation. Various physiological and metabolic responses to Si treatments were measured biweekly, and root biomass and viability were determined at the end of the trial. The data were analyzed with an analysis of variance and mean separations were performed with Duncan’s least significant difference at p= 0.05.

The results showed that Si applications at 6 oz/1000 ft2 significantly improved turf quality, leaf color ratings (Fig. 1), leaf chlorophyll content, antioxidant enzyme superoxide dismutase activity, and photochemical efficiency, especially when measured at the end of each dry-down cycle when the grass experienced severe drought stress. Si application at 3 lf oz/1000 ft2 also exhibited beneficial effects on creeping bentgrass, especially in late summer. The Si treatments at both rates increased root biomass (Fig. 2) and root viability as measured at the end of the trial. The results of this study indicated that the potassium silicate applied at both 3 fl oz and 6 fl oz/1000 ft2 improved summer stress tolerance of creeping bentgrass.

We would like to thank Harrell’s for the support of this research.

Fig. 1. Turf visual quality of creeping bentgrass as treated with potassium silicate (6 fl oz/1000 ft2, bottom) biweekly on July 20, 2022.

Fig. 1. Turf visual quality of creeping bentgrass non-treated control (top) on July 20, 2022.