Effects of Irrigation Volume and Nitrogen Fertilization on Redglobe and Michele Palieri Table-Grape Cultivars

The effects of water management and nitrogen fertilization, on yield, quality, and sensory profile of the red table-grape cultivars Redglobe and Michele Palieri were studied. Two irrigation volumes (1000 and 2000 m3/ha) and two nitrogen levels (120 and 180 kg/ha) were imposed. The effects of these parameters were cultivar-dependent. For Redglobe, irrigation resulted in significant increases in soluble solids and titratable acidity and significant decreases in resistance to compression and resistance to penetration. Increased nitrogen fertilization level exerted a significant effect only on titratable acidity (increased) and resistance to compression (decreased). Significant interactions between the two practices were demonstrated for soluble solids, pH, and resistance to compression. For Michele Palieri, increased irrigation resulted in significant decreases in soluble solids and resistance to penetration and significant increases in resistance to compression. Higher nitrogen caused decreases in berry weight but increases in soluble solid content and resistance to mechanical stress. Significant interactive effects were highlighted on yield, cluster weight, titratable acidity, and resistance to penetration. The lack of a significant correlation between physical/chemical and sensory results indicated that the changes induced by the agricultural practices on composition and mechanical behavior of berries were not perceptible by a trained panel.