Diurnal, changes in vine water status and gas exchange parameters of Vitisvinifera L-cv. Tempranillo grapevines as influenced by irrigation and pruning level

Diurnal changes in vine water status (psi(leaf) and psi(stem)), stomatal co nductance (gs) and gas exchange (A, E) were monitored in a vigorous Tempran illo vineyard subjected to two irrigation regimes (0.3 x ETo and non-irriga ted) and two pruning levels (10 and 18 shoots per vine). Irrigated vines we re significantly less stressed throughout the day, while pruning level only influenced water status during certain hours of the day. psi(leaf) was sig nificantly correlated with g(s), but this relationship depended upon ambien t PPFD and CO2 levels. Neither irrigation nor pruning level influenced vine photosynthesis (A) significantly,while stomatal conductance (gs) and trans piration (E) were both significantly higher in irrigated vines. The gs of a ll the treatments was not significantly different between the hours of 12:3 0 (morning) and 17:30 (afternoon), however the higher temperatures during t he afternoon increased vine E, while A was reduced. Photosynthesis was limi ted at temperatures above 30 degrees C, even though irrigated vines were no t stressed.