Desiccation avoidance and drought tolerance strategies in bermudagrasses

Abstract

The objective of this study was to characterize and compare mechanisms of drought avoidance and tolerance, specifically rooting characteristics, osmotic adjustment and antioxidant metabolism among different bermudagrasses. Six different bermudagrasses (‘Celebration’, ‘Tifway’, ‘TifTuf’, ‘UGB-70′, ‘UGB-42′ and ‘UGB-208’) were grown in field and growth chamber conditions and exposed to drought treatments. A range of drought performance was observed across bermudagrass genotypes with TifTuf being only the genotype to maintain a minimum acceptable turf quality rating of 6 at the end of drought treatments under field conditions. Along with TifTuf, UGB-42 and UGB-70 performed well in terms of percent green cover, normalized difference vegetation index (NDVI), leaf water status and membrane stability in both field and growth chamber conditions indicating these three genotypes had the best drought performance in the current study. Drought tolerant bermudagrasses were able to better maintain photosynthesis and transpiration after being exposed to drought. TifTuf had 15, 27 and 200 % greater osmotic adjustment (OA) compared to poor performing Celebration in 2017 and 2018 field, and grown chamber experiments, respectively. Antioxidant enzyme activities, including activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD), catalase (CAT) and glutathione reductase (GR), were mostly greater in drought-tolerant bermudagrasses. Greater antioxidant activities reduced formation of damaging H2O2 and lipid peroxidation in TifTuf, UGB-42 and UGB-70. TifTuf had 25 % greater total dry weight partitioned to roots compared to poorer performing UGB-208. Root viability was the greatest in UGB-42 and root length density (RLD) were greater in UGB-42 and UGB-70 compared to many other bermudagrasses. Results indicated better drought performances of bermudagrasses could be attributed both drought tolerance (particularly OA and antioxidant mechanisms) and desiccation avoidance (total dry weight partitioned to roots and root viability) traits.