Response of grapevine cv. Syrah to irrigation frequency and water distribution pattern in a clay soil

Water availability is one of the major factors that determine vineyard performance in many grape growing regions, so its implications have been widely studied before. However, for a given irrigation water amount, other aspects such as application frequency, or emitter spacing and flow rate (i.e., distribution pattern), may play a relevant role, but these factors have been scarcely studied. The aim of this work was to evaluate the agronomic implications of 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 during four consecutive seasons 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 water status that affected some aspects of vegetative development and yield components under both water availability conditions, although the effects observed were not the same every year. Berry size was the most sensitive parameter to changes in IrrF and DisP. The effects were more evident under low water availability. Soil texture has certainly conditioned the results obtained, since high frequency irrigation implied applying small amounts of water that resulted in limited superficial water bulbs, which probably favored water evaporation.