Drought avoidance of warm-season turfgrasses affected by irrigation system, soil surfactant revolution, and plant growth regulator trinexapac-ethyl

Abstract

A 2-yr study was conducted to investigate the effect of subsurface drip irrigation (SDI), the soil surfactant Revolution (modified methyl-capped block copolymer), and the plant growth regulator PrimoMaxx (a.i. trinexapac-ethyl [TE]), on rooting, stolons, and rhizomes, percentage green turf coverage, and turf quality of ‘Princess 77’ bermudagrass [Cynodon dactylon (L.) Pers.] and ‘Sea Spray’ seashore paspalum (Paspalum vaginatum Sw.). Grasses were grown on a loamy sand and irrigated with potable or saline ground water at 50% of reference evapotranspiration. Stolon and rhizome weight were not affected by water quality, Revolution, or TE, but SDI plots had greater stolon (1.000 vs. 0.627 g m−2) and rhizome biomass (0.856 vs. 0.493 g m−2) than sprinkler-irrigated plots. Grasses in drip-irrigated control plots showed higher root length density (RLD) at 0–10-cm depth (15.1 vs. 8.3 cm cm−3) and 10–40-cm depth (7.2 vs. 4.9 cm cm−3) and higher root weight density (RWD) at 0–10-cm depth (3.5 vs. 2.2 g cm−3) than their sprinkler-irrigated counterparts. Both RLD and RWD correlated significantly with turfgrass quality (August and September) and green turf cover (July–September). Chemical treatments in combination with irrigation from a sprinkler system resulted in thinner roots and higher RLD at all depths in 2013 when values were compared with the untreated control. Revolution, TE, and SDI all enhanced grasses’ drought avoidance and turf quality, but chemical treatments did not appear to provide additional improvements to grasses in plots irrigated with SDI.