Summer dormancy and drought survival of moroccan ecotypes of orchardgrass

Summer dormancy improves drought survival and autumn recovery of perennial forage species in Mediterranean areas. Morocco has served as a source of germplasm for orchardgrass (Dactylis glomerata L.) breeding, but little is known of the incidence and variability of the summer dormancy trait in Moroccan orchardgrass germplasm. This paper characterizes summer dormancy and summer drought survival in Moroccan ecotypes of orchardgrass. Ten Moroccan ecotypes and the cultivar Kasbah were studied in the field in Guich experimental INRA, Rabat, Morocco. Two trials were conducted in irrigated (to test summer dormancy) and in rainfed conditions (to test drought survival after summer). Under irrigation, Moroccan ecotypes of orchardgrass and Kasbah were summer dormant. According to a summer dormancy index and a combination of physiological responses, most ecotypes and Kasbah were found completely dormant. A single ecotype was considered incompletely dormant. After intense first year summer drought, plant survival was correlated (P < 0.001) with water soluble carbohydrate (WSC) content and osmotic potential in immature leaf bases (r = 0.67 and 0.62, respectively). Two Moroccan ecotypes exhibited higher post-drought survival after summer drought (98%) than Kasbah (90%) (P < 0.01). After a second year with severe drought, an ecotype outyielded Kasbah for autumn recovery (P < 0.001). Moroccan germplasm exhibited good levels of dormancy and agronomic performance that would be desirable in breeding programs.

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