Pre dawn, stem and leaf water potential evolution in Vitis vinifera L. cv Nero d’Avola/1103 P. under different water regime

Abstract

Pre dawn, stem and leaf water potential evolution under different water regime were investigated in Nero d’Avola cultivar grafted onto 1103 Paulsen. The study was carried out in Rapitalà winery located in Alcamo DOC area in western Sicily. The vines were 2.4 m x 0.95 m spaced, for a density of 4385 vines/ha. Vines were trained to a vertical trellis system, spur pruned. The vineyard was drip irrigated (4 l/h). Three treatments were applied: 1. vines grown without irrigation water: dry condition; 2. vines irrigated until véraison with 560 m3 : late stress; 3. vines irrigated until ripeness with 1120 m3 : no stress. The aim of the study was to find the different behaviors of Ψp, Ψl e Ψs during the season. Water potential measurements (Pre dawn (Ψp), leaf water potential at midday (Ψl) and Stem water potential (Ψs) in bagged leaves at midday, both in shaded leaves) were determined using a Scholander Chamber, the day before and after each irrigation. Different water potential methods showed water content variation (in following irrigation) in different dates. In dry condition Ψp was good indicator of plant water condition whereas Ψl e Ψs during the season, had variable behaviour. Ψp evidenced better differences, between irrigated and not irrigated vines, compare to Ψs and Ψl respectively. So that Ψp is good indicator of irrigation response, in the earlier season. However Ψs and Ψl were good indicators of irrigation response during the end of the season. Higher variability was respectively found for Ψl and Ψs than Ψp This was due to the environmental condition influences. In conclusion a higher number of leaves samples is necessary for Ψs and Ψl than Ψp