Enhancing drought resistance in warm-season turfgrasses: Fourteen years of progress through a multistate collaborative project across the southern United States

In turfgrass breeding, drought resistance is a primary trait for improvement due to scarcity and reduced quality of water for irrigation. Therefore, in 2010, the turfgrass breeding programs at six public universities joined efforts to address these challenges by cross evaluating breeding lines for the most economically significant warm-season turfgrass species in the southern United States through a United States Department of Agriculture-National Institute for Food and Agriculture Specialty Crop Research Initiative funded project. Three breeding cycles were associated with three completed (2010–2014, 2014–2019, and 2019–2024) collaborative grant projects, but the efficiency of this partnership in terms of gains from selection has not been measured. Our objectives were to (1) estimate the expected and realized genetic gain for drought resistance and turfgrass quality for three breeding cycles, (2) compare cultivars developed with support of the projects versus standard cultivars in a historical data analysis, and (3) compare genetic gain for traits assessed visually versus using small unmanned aircraft systems imagery, both in drought and non-drought environments. For these purposes, historical data were investigated with a retrospective analysis of project trials evaluated 2011–2024. Our findings for the realized genetic gain demonstrated progress in enhancing drought resistance in bermudagrass, St. Augustinegrass, seashore paspalum, and zoysiagrass. In addition, notable positive increments for this trait were documented for each cycle compared to the standard cultivars, particularly in bermudagrass, St. Augustinegrass, and zoysiagrass. While heritability was higher for visually assessed traits, genetic increments were more pronounced for imagery-assessed traits.