Performance of Two Seashore Paspalum (Paspalum vaginatum Sw.) Varieties Growing in Shallow Green Roof Substrate Depths and Irrigated with Seawater

Abstract

The continuing decline in global drinking water reserves necessitates finding alternative water sources for turfgrass irrigation, especially in southern semi-arid Mediterranean countries. The aim of the present study was to evaluate the potential of using seawater for irrigating two varieties of seashore paspalum (Paspalum vaginatum Sw.), “Marina” and “Platinum ΤΕ”, growing in shallow green roof substrates, and to determine their recuperative capacity after the termination of the salt stress period. The greenhouse study comprised of 48 lysimeters equipped with extensive green roof layering. Treatments included: (i) two substrate depths (7.5 cm or 15 cm) and (ii) three seawater irrigation regimes (7 mm, 15 mm, or 45 mm every two days). Measurements included the determination of green turf cover (GTC) as well as the leaching fraction (LF) and leachate electrical conductivity (ECL) draining from the lysimeters. It was found that during the 46-d salt stress period, none of the seawater irrigation regimes managed to maintain acceptable GTC levels for both seashore paspalum varieties. Increasing the green roof substrate depth from 7.5 cm to 15 cm resulted in GTC improvement. During the recovery period, the use of potable water as irrigation source improved GTC levels. After 40 d the recovery was complete since GTC exceeded 90% in all treatments for both varieties. Regression curves correlating GTC response to ECL can be used to estimate the leaching requirements of turfgrasses grown in shallow green roof systems when irrigated with saline water.

Tolerance of Tall Fescue (Festuca arundinacea Schreb.) Growing in Extensive Green Roof Systems to Saline Water Irrigation with Varying Leaching Fractions

“…from 5 December 2019 to 30 May 2020. The experimental setup was similar to that of a previous study by the authors [20]. It involved 24 polyvinyl chloride (PVC) lysimeters with an inner diameter of 300 mm and a surface area of 0.07 m 2 (Figure 1), arranged on levelled benches.…”

“…The green turf cover (GTC) percentage was calculated throughout this study by taking digital images of each lysimeter on each irrigation date, following the methodology by Ntoulas and Varsamos [20]. The GTC was assessed through digital image analysis using SigmaScan Pro Version 5.0 software (Systat Software Inc., San Jose, CA, USA), as outlined by Richardson et al [35].…”

“…The response of GTC to EC L during the salinity stress period was analyzed using the segmented linear regression model presented by Ntoulas and Varsamos [20]. The GraphPad Prism software, version 6.01 for Windows (GraphPad Software Inc., San Diego, CA, USA), was utilized for conducting regression analysis [36].…”

“…Consequently, alternative water sources, such as saline water, grey water, and recycled stormwater runoff, have been explored for green roof irrigation [17][18][19]. In rare cases, seawater has also been proposed as an alternative source of green roof irrigation [20,21]. Saline irrigation water sources include naturally saline groundwater as well as groundwater salinized due to salt leaching or seawater intrusion into the aquifer.…”

Impact of Salinity on Germination and Seedling Growth of Four Cool-Season Turfgrass Species and Cultivars

“…Control pots were irrigated with distilled water. After the targeted salinity levels were achieved, the irrigation water depending on field capacity was applied for a period of seven weeks (March 07 to April 26 at each year) at greenhouse condition [25]. Fifty days after emergence, seedlings were taken by gentile washing the soil, and each seedling were separated into roots and shoots [16].…”