Pigment Content and Quality of Drought Stressed Warm-Season Turf Species Treated with Plant Growth Regulators.

Plant growth regulators (PGR) and soil surfactants are purported to decrease turfgrass irrigation needs without a loss in quality. A study was conducted at New Mexico State University in Las Cruces, NM during 2010 and 2011 to determine turf quality and drought stress of bermudagrass [Cynodon dactylon (L.)] cultivar Princess 77 and seashore paspalum [Paspalum vaginatum (Swartz)] cv. Sea Spray treated with either a soil surfactant (Revolution) or a PGR (Primo MAXX). Irrigation was applied daily at 50% ET₀ from either a sprinkler or a subsurface-drip system with either saline (TDS = 1600 ppm) or potable (500 ppm) water. Normalized Difference Vegetation Indices (NDVI) and visual ratings were collected bi-monthly from June until November to assess turf stress and quality, respectively. Chlorophyll a and b and carotenoid content were assessed monthly during the summer months to determine whether pigment content was associated with resistance to environmental stresses. Primo MAXX increased turf quality, chlorophyll and carotenoids content during the summer and enhanced fall color retention. Sprinkler-irrigated plots exhibited higher turf quality during the summer and saline irrigation water decreased turf quality of seashore paspalum on plots treated with Revolution. Bermudagrass irrigated with saline water and treated with Primo showed higher quality than the control, but lower quality in comparison to bermudagrass treated with Primo and irrigated with potable water. A linear regression described the relationship between NDVI and visual quality; however no correlation was found between chlorophyll content and either NDVI or visual ratings.