Irrigation

Grapevines were not traditionally irrigated in this region. However, recent studies have shown that  under certain soil and climatic conditions, such as steep, highly permeable, and dry soils, water deficits may reduce the development of functional leaf area, leading to premature leaf senescence and ultimately negatively affecting fruit quality at harvest.

In recent vineyard restructuring efforts, Vineyard plantings have increasingly shifted to mid-slope sites, which are better suited to producing high-quality grapes but where water deficits may need to be considered.

Drip irrigation is the most suitable method for grapevine cultivation, and pressure-compensating emitters should be chosen to ensure a uniform discharge rate along the line.

Irrigation scheduling should be based on criteria that take into account vine water status and/or soil moisture content. This is due to the fact that excessive irrigation is not only wasteful but also causes nutrient leaching which may adversely affect fruit quality, particularly during ripening. A moderate level of water stress during ripening is well-known to enhance fruit quality. However, severe water deficits occurring between berry development and veraison, may lead to irreversible berry size and weight losses, even after irrigation.

Under the region’s normal water regime, vineyards may require irrigation starting in the first half of July (near veraison)—depending, obviously, on the year’s weather conditions, soil type, and the extent of the root system.

Baseline leaf water potential measurements can be used to estimate vine water stress. However, not all growers have easy access to this method, in which case visual assessments supported by simple tensiometers may be a practical alternative.

Finally, irrigation water quality is an important consideration, even more so when fertigation is used. For example, water pH levels above 6.5 can promote the precipitation of iron, calcium, magnesium, and phosphate compounds, reducing their solubility and clogging up emitters. What is more, adding fertilizers to irrigation water increases its salinity (salt concentration and therefore osmotic pressure), making it more difficult for vines to absorb both water and nutrients.