Interactive Effects of Abiotic Stress and Clipping on Biomass Accumulation and Root Architecture in Lolium perenne and Poa pratensis Cultivars During Turf Establishment and Early Development

The effects of climate change pose challenges to 21st-century society. Abiotic stresses such as salinity and drought represent a risk to biodiversity and the sustainability of urban and managed grasslands. In this study, we evaluated the interactive effects of mechanical defoliation (clipping), water deficit, and salinity under greenhouse conditions on several cultivars of two cool-season turfgrass species, Lolium perenne L. (‘Columbine’, ‘Allstarter’, ‘Esquire’) and Poa pratensis L. (‘Sombrero’, ‘Dakisha’, ‘Conni’). Water stress reduced relative leaf fresh and dry weight from approximately 66% to 28% and from 76% to 30%, respectively. Salinity induced moderate responses, mainly affecting root-related traits. Clipping reduced biomass, with relative leaf fresh and dry weight decreasing from 64% to 27% and from 86% to 28%, but it also stimulated compensatory responses, including increases in length increment from 0.17 to 0.29 cm day−1, and in leaf and root water content from 63% to 67%. Lolium perenne showed greater root development than P. pratensis with higher root length (95% vs. 75%) and root surface area and volume (66% vs. 51%). Cultivar differences were evident, with ‘Columbine’ and ‘Allstarter’ showing greater stability, whereas ‘Dakisha’ was more sensitive. These findings highlight the importance of cultivar selection and clipping management under stress conditions.