Nowadays a great attention is focused on minimizing the intensive amounts of mineral nitrogen fertilization by applying organic aminding such as humic and fulvic acids which considered the main fraction of humic substances and fulvic acid could stimulate plant growth and consequently yield. To achieve this aim an experiment was conducted on 14 years old Superior seedless grapevines in 2020, 2021 and 2022.
Application of mineral-N at 50 to 75% of recommended dose of nitrogen (RND) along 25% of humic acid or/and fulvic acid. The experimental vines were arranged in a complete randomized design with four treatments and three replications two vines per each. The obtained results could be summarized as follow:
Using RDN via 50 to 75% mineral plus 25% Humic acid and/or fulvic acid significantly increased, leaf area, pruning wood weight, and leaf total chlorophyll as well as leaf nutrient composition compared to use RDN via mineral N fertilizer alone. All combined fertilization treatments significantly increased the yield and improved the cluster and berry traits compared to use RDN via mineral source only.