Research Updates from Virginia Tech continued
Testing Effects of Glycine Betaine (GB) and Choline on Physiological Fitness and Quality of Creeping Bentgrass under Heat and Mild Drought Stress By Xunzhong Zhang, Ph.D. and Mike Goatley, Ph.D. School of Plant and Environmental Sciences Virginia Tech, Blacksburg, VA
Introduction and Objectives Exogenous application of certain small molecule organic compounds has been used as a tool to improve cool-season turfgrass quality and physiological fitness during summer stress as characterized by temperature and/or drought. Glycine betaine (GB) is one of the most important osmoprotectants found in plants and it can stabilize cell membranes, protect proteins and photosynthetic reactions, and mitigate oxidative damage to cells that occurs during stress. Choline is an important primary precursor of GB. The objectives of this study were to investigate if foliar application of GB and Choline, alone or in combination, could improve creeping bentgrass quality and physiological fitness under heat and mild drought stress conditions.
Research Procedures Mature ‘Memorial’ creeping bentgrass plugs were transplanted into 6 inch pots filled with a USGA sand. After 4 weeks of nonstressed growth, we placed the pots in a controlled environment growth chamber at 95 F day (12 h)/77 F night, light intensity at 400 µmol m-2 s-1, 12 h photoperiod, and 60% RH. Water was replaced daily at 40% of measured evapotranspiration (ET). Seven treatments were arranged in a completely randomized
block design with four replications. The treatments included 1). Fertilized control; 2). GB at 0.5 oz/1000 ft2); 3). GB at 1.0 oz/ 1000 ft2; 4). Choline at 0.5 oz/1000 ft2; 5). Choline at 1.0 oz/ 1000 ft2; 6). GB at 0.5 oz/1000 ft2 + Choline at 0.5 oz/1000 ft2; and 7). GB at 1.0 oz/1000 ft2 + Choline at 1.0 oz/1000 ft2. Treatment solutions were applied at 1 gallon/1000 ft2. All seven treatments received identical N input at 0.15 lb N/1000 ft2 every 14 days. The stress period of the trial lasted for 8 weeks, with a total of 4 treatment applications occurring every 14 days. Visual leaf color, photochemical efficiency (PE), clipping yield, leaf chlorophyll, carotenoid and leaf proline content, root growth characteristics, and root viability were measured every 14 days.
Results Foliar application of Choline, alone or in combination with GB, improved leaf color, PE, and increased chlorophyll, carotenoid, and proline content of creeping bentgrass under heat and mild drought stress conditions. Foliar application of GB+Choline at low rate consistently improved root biomass, root length, and root surface area. Overall, Choline alone or low rate plus low rate GB exhibited greater beneficial effects on physiological fitness and visual quality of creeping bentgrass during heat and mild drought stress conditions (Photo 1). The results of this study suggest biweekly foliar application of Choline with or without GB may improve creeping bentgrass quality during summer stress.
Acknowledgement We’d like to thank Harrell’s for the support of this project.
PHOTO 1: Leaf color of creeping bentgrass as affected by GB+Choline treatments at day 56 of simulated heat and drought stress.
30 | VIRGINIA TURFGRASS JOURNAL January/February 2021 www.vaturf.org
