Effect of Saline Water Additions On Irrigated Grapes Under Field Conditions.

A total of 704 Cabernet Sauvignon (CS8) vines were grafted on 10 different rootstocks or planted on their own roots in the summer 2008 as part of a new vineyard planting on an alluvial terrace above the Estrella River in the Paso Robles winegrowing region. The planting was done on two sites with different soil types within the same vineyard block. Soil type 1, an Inceptisol, is a light sandy loam soil throughout with reduced water holding capacity due to its texture and high gravel content. Soil Type 2 is an Alfisol with a sandy loam surface texture over a heavier clay loam subsurface, with higher water and nutrient holding capacities than soil 1.

Vines were planted in four rows on both plots and have been managed similarly.  Starting in the Fall 2011, a saline solution in concentrations of 1.75, 3.5 and 4.5 dS/m was dispensed through the drip line on one row in each plot. The vines have been monitored for chloride exclusion every two weeks, starting at the bloom phonological stage, measuring leaf blade chloride content. Three years after planting, the vines exhibit marked differences in growth rates and canopy development, as measured by the pruning weights collected for all vines in 2010 and 2011. Tissue analyses performed in 2009, 2010 and 2011 showed differences between rootstocks for all nutrients studied. In most cases, the rootstock ranking order, with respect to nutrient content, was similar for vines grown on the Alfisol and those grown on the Inceptisol, but there were many exceptions to this trend. Chloride exclusion by the salt resistant rootstocks was more pronounced. Obvious signs of salt injury were not immediately observed on the plants in the trial until veraison in 2012, suggesting a slow process of salt accumulation under field conditions.