Effect of post veraison regulated deficit irrigation in production and berry quality of Autumn Royal and Crimson table grape cultivars

A field experiment was performed in two drip-irrigated seedless table grape vineyards (Vitis vinifera L. cv. Autumn Royal and Crimson) from 2007 to 2009 in a semiarid area of north-eastern Spain to evaluate the effect of post veraison regulated deficit irrigation (RDI) on the grape yield and quality. The same experimental layout was used in both cultivars. Two RDI treatments were compared with a full irrigation treatment in both cultivars. The full irrigation treatment (T1) was irrigated at 100% of the net irrigation requirements (NIR). The RDI treatments (T2 and T3) were irrigated as T1 except from veraison until harvest, when they received 80% and 60% of NIR, respectively. Average water saving in T3 was around 15% of the seasonal water applied in the treatment T1 while this saving in T2 ranged between 6% and 8%. Similar grape yields were obtained in the different irrigation treatments for the Autumn Royal cultivar during 2007 and 2009. However in 2008 the yield of T2 (46.0kgvine−1) was significantly higher than in T3 (34.4kgvine−1). For the Crimson cultivar, the grape yield of T3 was significantly lower than T2 in 2007 and 2008. In 2009 low grape yields were obtained in all treatments of the Crimson cultivar and no differences were observed between them. The quality parameters of the berry in both cultivars were not affected by the irrigation treatments. Berry cracking in Autumn was high in 2007 ranging from 14.7% to 21.4% and very low in 2008 and 2009 ranging from 1.5% to 4.3%. The reduction of berry cracking was attributed to the splitting of the irrigation dose in two applications per day, one at midday and the other one at night. Significant differences between irrigation treatments were observed in the CIELab color parameters of the berry skin in the Crimson cultivar. The overall results during the three study years showed that high grape yields of very good quality can be obtained with moderate regulated deficit irrigation in the post veraison phase without affecting grape quality in the Autumn and Crimson seedless cultivars in the arid conditions of the lower Ebro Valley in north-eastern Spain