Ji. Garcia-plazaola et Jm. Becerril, Effects of drought on photoprotective mechanisms in European beech (Fagus sylvatica L.) seedlings from different provenances, TREES, 14(8), 2000, pp. 485-490
The effects of drought on photoprotection mechanisms of three beech provena
nces from three contrasting climatic origins have been studied. Morphology
differed among provenances, with a lower leaf area/fine roots ratio in the
xeric populations (Moncayo). This characteristic allowed this provenance to
respond later than the others to a drought-stress treatment. However, in d
esiccating leaves the stability of PSII was higher in the plants from the s
tressful climate of the Pyrenees (Belagoa). Drought resulted in a reduction
in pigment content (except in Belagoa) with simultaneous increases in anth
eraxanthin, zeaxanthin and tocopherol pools. These molecules play an import
ant photoprotective role and reached similar values in stressed leaves from
the three provenances. These antioxidants also protected the leaves from p
araquat-induced oxidation. It is concluded that drought tolerance in the st
udied xeric ecotype is based to a greater extent on morphological character
istics than on a better photoprotective system.