A preliminary study on physiological changes of Central European beech provenances in response to progressive drought stress

Abstract

Four-year seedlings of two European beech ecotypes (Fagus sylvatica L.) were grown under well-watered and drought conditions for 51 days. Two populations were from the same medium-wet climatic region, but they differed in altitude. The results showed that there were significant differences in responses to different watering regimes in both provenances tested. Drought reduced quantum yield of photosystem II (PS II), decreased electron transport rate (ETR) through photosystem II and photochemical quenching (qP). More dissipation of energy excess (qN) was found in PV1 under drought-stress conditions. Water-deficit was associated with increases in proline content. Moreover, drought-treated seedlings of both provenances had significantly decreased chlorophyll pigment contents (Chl a, Chl b, Chl a + b) and carotenoids (Car x + c). Drought also influenced the height and stem diameter of seedlings. However, the differences between the provenances were statistically significant in drought stressed plants only in case of proline content and fluorescence parameter qN.