Drought effects on C, N, and P nutrition and the antioxidative system of beech seedlings depend on geographic origin

Abstract

In future, prolonged summer drought and heat will constitute a major risk for the cultivation of shallow-rooting beech in Central Europe and will negatively affect the productivity of beech forests. In a pot experiment under controlled conditions, the influence of long-term (28 d) water deprivation on nitrogen (N), carbon (C), phosphate (Pi), and ascorbate (ASC) concentrations was examined in leaves and fine roots of beech seedlings (Fagus sylvatica L.) from six provenances originating from Central Europe (Germany: Neidenstein and Illertissen, intermediate habitats), the Balkan peninsula (Croatia: Zagreb and Gospic, wet habitats), and Southeast Europe (Bulgaria: Kotel, Greece: Paikos; dry habitats). The goal of the study was to identify beech provenances well adapted to water limitation during summer drought events. Our results suggest that N might be involved in the alleviation of water scarcity, whereas Pi might become a limiting factor for forest growth during drought periods. Drought stress resulted in significant changes of ASC pools in leaves and fine roots and the ASC redox state. Under well-watered and under drought conditions, ASC in leaves was the most important factor causing differences between the provenances examined. Finally, a link between P nutrition and the capacity of antioxidative stress defense by ascorbate could be highlighted. Based on observations from this study, beech seedlings from three origins (Paikos, Zagreb, and Neidenstein) might constitute beech provenances well adapted to water shortage in summer. This conclusion is drawn from the high potential of these provenances to alleviate oxidative stress during water shortage.