Nitrogen Fertilization Effects On Protein Content of Warm Season Grasses Under Saline Drip Irrigation.

Nitrogen fertilization has been shown to increase protein content during a warm-season grass plant’s dormancy which in return provides protection from cold damage and a faster green up during spring. A study was conducted from summer of 2009 to spring of 2010 at New Mexico State University to investigate the effect of nitrogen fertilization on winter and spring protein content of seashore paspalum (Paspalum vaginatum) ‘Sea Spray’ and bermudagrass (Cynodon dactylon) ‘Princess 77’ turf. Two nitrogen rates, 10 and 20 g m^-2year^-1 on Sea Spray and 20 and 30 g m^-2 year^-1 on Princess 77 from 5 different fertilizer sources (urea liquid, urea granular, Burley green^™, CoRoN^®, and a granular slow release) were applied to turfgrasses. Plots were irrigated with either potable (370 ppm) or saline (1900 ppm) water from either sprinkler or subsurface drip irrigation systems. During the months of December, February, and April, stolons and rhizomes were collected to determine protein content following the Bradford method. Generally, bermudagrass exhibited higher protein content (5.5 mg g^-1) than seashore paspalum (4.45 mg g^-1) and rhizomes had higher protein content (5.6 mg g^-1) compared to stolons (4.4 mg g^-1). Irrigation system and water quality had no effect on protein content of the tested grasses. When data were averaged over all treatments but analyzed separately for each sampling month, protein content reached 5.9 mg g^-1 in December and decreased subsequently to 4.8 mg g^-1 in February and to 4.3 mg g^-1 in April. The process of protein depletion during winter and spring coincided with spring green up. Fertilizer type and rate did not affect protein content in both species. Longer term research is necessary to determine whether or not higher protein content enhances spring green-up