Relationship between stomatal density and winter hardiness in olive (Olea europaeaL.)

Abstract

SummarySerious damage caused by cold has frequently been reported from several countries where olives are grown. Following the 1985 frost in central Italy (−20°C to −25°C), a widespread survey was carried out into the damage suffered by the cultivars on three sites in Tuscany. The cultivars were classified as hardy, semi-hardy and not-hardy. The numbers of stornata in the leaves of cultivars rated as hardy were significantly lower than those of cultivars rated not-hardy. Stomatal numbers of the one clone in the intermediate class fell within the range of counts of the hardy and not-hardy cultivars. The numbers of stornata, influenced at times by their position on the leaves (apex, central and base), may well constitute a simple and effective selection criterion for screening olive plants for winter hardiness.