Effect of Drought on Genotype-By-Environment Interaction on Warm-Season Turf Grasses.

One of the benefits of the USDA-NIFA (SCRI) project “Development and commercialization of drought- and salinity-tolerant turfgrass species for the southern and southeastern United States” is the possibility of observing and recording the performance of turfgrass under different and contrasting locations in the Southeast. This collaboration involves Texas A&M AgriLife, North Carolina State University, University of Georgia, Oklahoma State University, and the University of Florida. Field experiments have been established since 2010 for bermudagrass (Cynodon spp.), zoysiagrass (Zoysia spp.), St. Augustinegrass (Stenotaphrum secundatum), and seashore paspalum (Paspalum vaginatum). These experiments have been measured repeatedly every year under normal and drought conditions. Four years of data from seven locations across the southeastern U.S. were analyzed using mixed models. Results indicate that an important genotype-by-environment interaction exists for most warm season grasses in this region. Most interestingly the genetic parameters change, sometimes dramatically, when only measurements under drought conditions are used in the analyses. As intense drought conditions in the South become more frequent these results should be carefully examined by plant breeders when making genotype selections to develop the next generation of improved cultivars.