Physiological responses of "Falanghina" grapevines in soils with different water availability in Southern Italy

The eco-physiology of 'Falanghina' grapevine was studied in Telesina valley(Southern Italy) in two nearby vineyards. The soil was characterised by a higher, site 1(T1) and a lower, site 2 (T2), water availability. Soil water content, leaf water statusand gas-exchanges were monitored during summer 2004 and showed that in the T1and T2 the vines were subjected to different degree of water stress as soil moisture wasdepleted. Midday leaf water potential decreased in summer compared with spring butremained quite stable during summer, suggesting a nearly isohydric behaviour for thiscultivar, with no appreciable difference between the two sites. Conversely to leaf waterpotential, stomatal conductance to water vapour strongly decreased during summerand at beginning of August showed quite higher values (0.204 mol m-2s-1) in the T1compared with T2 (0.065 mol m-2s-1). The response of grapevine to water deficit wasthe closure of stomata and not a noticeable decrease in leaf water potential. Comparedwith stomatal conductance, CO2 assimilation showed a lower sensitivity to soil waterdeficit, resulting in a decrease of intrinsic water use efficiency during occurrence ofstressful conditions of summer. This information can be useful to understand therelationships between soil characteristics, water relations and grape quality.INTRODUCTION