Foliar Application of Mixture of Amino Acids and Ascophylum nodosum Extract Improve Growth and Physico–Chemical Quality of Grapes

Foliar applications of mixture of amino acids and Ascophylum nodosum (Seaweed) extract at different growth stages were investigated on the growth and physico–chemical characteristics of grapes cv. ‘Perlette’. Grapevines were sprayed with 0.5 ml•L^-1 aqueous solution of mixture of amino acids and seaweed extract plus 0.01% Tween-20 as surfactant at flowering stage, fruit setting stage, flowering + fruit setting stages, or flowering + fruit setting + one month after fruit setting stages. Unsprayed grapevines were kept as control. Grapevines treated with multiple applications of mixture of amino acids and seaweed extract at flowering + fruit setting + one month after fruit setting stages (T5) exhibited significantly higher leaf size (41.5%), chlorophyll content (18.15 mg•g^-1), berry setting (6.66%), number of bunches per cane (6.66%), rachis length (13.5%), berry weight (14.78%), berry size (7.33%), soluble solid concentrations (SSC, 16%), SSC: titrable acidity (TA) ratio, (29), pH of juice (3%), total sugars (28%) and reducing sugars (35%) with reduced berry drop (10.6%) and ascorbic acid (28.6%) contents as compared to all other treatments. Treated grapevines did not exhibit any significant change in the leaf mineral contents, bunch size, and bunch weight. In conclusion, multiple foliar applications of 0.5 ml•L^-1 mixture of amino acids and seaweed extract can be used effectively to improve growth and physico–chemical berry quality of grapevine cv. ‘Perlette’.