Performance of diploid and interploid hybrids of St. Augustinegrass under moderate shade

Abstract

Shadetolerance is an important factor for cultivar selection in urban areas. Diploid (2n = 2x = 18) cultivars of St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] with moderate to high shade tolerance have been popular choices for residential and commercial landscapes in the southern United States. This study evaluated 26 elite drought resistant diploid and interploid (polyploid × diploid) hybrids and four commercial cultivars under 75% continuous shade from 20 June 2017 through 30 Oct. 2018. Biweekly data were collected during the growing season for percent green cover, visual turfgrass quality, canopy color, shoot density, and daily leaf elongation rates (DER; mm d–1). Spring greenup was rated annually, and to gray leaf spot incidence was rated when naturally occurring. All genotypes lost green cover through 2017, and greenup was delayed transitioning into the summer of 2018 when most diploids struggled to recover from disease, shade, and winter injury whereas, on an average, interploid hybrids reached up to 84.0% green cover. Daily leaf elongation rates were lower for diploids than polyploids in both years. Turfgrass quality, color, and density generally declined under shade as expected. Overall, three interploid hybrids (DALSA 1329, 1404, and 1406) were the top performers demonstrating good retention of turfgrass performance traits and reduced DER under shade.

Effect of acute shade on the canopy morphology and evapotranspiration rates of three turfgrasses

“…These findings are indicative of shade avoidance responses, and the pattern of response among species was surprising, given the conventional theory that shade tolerance is accompanied by a diminished shade avoidance response (Petrella & Watkins, 2020). Similarly, Meeks and Chandra (2021) reported a poor relationship between the leaf extension rate and apparent shade tolerance in 30 St. Augustinegrasses [Stenotaphrum secundatum (Walter) Kuntze] evaluated under shade conditions. The present study supports the theory that shade avoidance is less important, to some extent, than light use efficiency in shade tolerance in turfgrasses.…”

“…Turfgrass species and cultivars can vary widely in shade tolerance (Chhetri et al., 2019; Jiang et al., 2004; Meeks & Chandra, 2021; Petrella & Watkins, 2020). How these differences in shade tolerance influence the response of ET rates to varying light environments has not been widely reported.…”

Phenotypic performance, production, and nutritional quality of Stenotaphrum secundatum var. Steno Agrinak

“…Diploid cultivars of S. secundatum (Walt.) Kuntze with moderate to high shade tolerance have been popular choices for residential and commercial landscapes in the southern United States [3].…”

Registration of ‘DALSA 1618’ St. Augustinegrass

“…(Genovesi et al., 2017b). Intraspecific hybrids of St. Augustinegrass have been shown to exhibit enhanced turfgrass quality under extreme drought conditions and moderate shade environments (Chandra et al., 2015; Meeks & Chandra, 2019, 2021). ‘DALSA 1618’ (Reg.…”