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 status and gas-exchanges were monitored during summer 2004 and showed that in the T1 and T2 the vines were subjected to different degree of water stress as soil moisture was depleted. Midday leaf water potential decreased in summer compared with spring but remained quite stable during summer, suggesting a nearly isohydric behaviour for this cultivar, with no appreciable difference between the two sites. Conversely to leaf water potential, stomatal conductance to water vapour strongly decreased during summer and at beginning of August showed quite higher values (0.204 mol m-2s-1) in the T1 compared with T2 (0.065 mol m-2s-1). The response of grapevine to water deficit was the closure of stomata and not a noticeable decrease in leaf water potential. Compared with stomatal conductance, CO2 assimilation showed a lower sensitivity to soil water deficit, resulting in a decrease of intrinsic water use efficiency during occurrence of stressful conditions of summer. This information can be useful to understand the relationships between soil characteristics, water relations and grape quality. INTRODUCTION