Growth and Drought Responses of Three Prunus spinosa L. Ecotypes
Conservationists and some government guidelines emphasize preferential use of local population propagules with the assumption that they are locally adapted and preserve genetic diversity. We evaluated growth and morphological, physiological and biochemical responses to drought of three populations of Prunus spinosa to check whether they are inclined to local adaptation. Two German and one Italian population of Prunus spinosa L. were cultivated in 5 litre pots on a container area for years and later transferred to a greenhouse for drought experiments. Plants were subjected to three levels of watering regime: two drought treatments of irrigating 25% (fast stress) or 50% (slow stress) of lost water, and well-watered control plants. Growth was evaluated during the cultivation period while morphological, physiological and biochemical responses to drought were evaluated in the greenhouse. There was no evident advantage of local adaptation, but the phenological stage (fruiting) proved to have an influential effect on drought responses. The German populations (BB and RPF) did not differ in any aspect. But the Italian population (ITA) differed from the German population (BB) in growth, fruit load and the intensity of leaves shedding. The Italian population also significantly declined its stomata conductance in day three after drought initiation but not further as drought progressed. Concerning biomarkers, BB increased glucose, sucrose fructose and proline in both stress treatments. ITA increased glucose and fructose due to slow stress while only fructose increased due to fast stress. ITA sucrose concentration was unaffected by stress treatment. German and Italian populations differed significantly only in fast stress: BB had higher sucrose concentration than ITA. However, ITA had higher proline concentration than BB.
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