Effect of irrigation frequency and water distribution pattern on leaf gas exchange of cv. 'Syrah' grown on a clay soil at two levels of water availability

The implications of water availability in grapevine physiology have been widely studied before. However, for a given irrigation water amount, the effect of other aspects such as application frequency, or emitter spacing and flow rate (i.e.: distribution pattern) has been scarcely studied, with nearly no previous research on their implications on leaf gas exchange. The aim of this work was to evaluate the physiological response of grapevine to two irrigation frequencies (IrrF, every 2 and 4 days) and two water distribution patterns (DisP, 2 L h−1 emitters every 0.6 m vs. 4 L h−1 emitters every 1.2 m). The experiment was carried out in a cv. Syrah vineyard with a clay soil in central Spain, and the two factors were evaluated under two water availability conditions (low and medium). IrrF and DisP promoted changes in leaf gas exchange. Under low WA conditions, plants irrigated every 4 days had higher average net assimilation than plants irrigated every 2 days. Under medium WA conditions leaf gas exchange depended on the day of measurement with respect to irrigation. Water distribution pattern effect was less evident, but plants with closer emitters performed better under medium WA. The results obtained suggest that variations in irrigation frequency and water availability promote plant acclimation to water deficit conditions, more intense as irrigation dose was lower and as irrigation frequency was higher.