Local Adaptation? — Physiological and Biochemical Responses of four Hazelnut Populations to Drought and Possible Impacts on Tree Nurseries

Outplanting performance of trees and shrubs cultivated in tree nurseries is assumed to be better if propagation material is sourced from the designated areas of future growth. However, this requires a local nursery to produce that cultivar, which might reduce the availability of that species. In this study we evaluated drought reactions of 2.5-year-old hazelnut (Corylus avellana L.) from four population origins. After container cultivation, plants were subjected to drought by irrigating 25% (fast stress) or 50% (slow stress) of the lost water. Control plants were well irrigated. Depending on stress development and hence stress duration, different physiological (stomatal conductance, predawn water potential, relative water content) and biochemical (glucose, fructose, sucrose, starch, proline) responses to drought were found. Independent of stress development, only few differences among populations were found. These differences were mostly not related to precipitation in their area of origin, suggesting no local adaptation within the ecological range investigated.