Effect of Soil Application Mineral Nitrogen, Humic Acid and Dry Yeast on Growth and Fruiting of Red Roomy Grapevines

Six-year-old Red Roomy grapevines cultivated at the Experimental Orchard of the Faculty of Agriculture, Assiut University, Egypt, were the subject of this study in the 2022 and 2023 growing seasons. To investigate how Red Roomy grapevines' vegetative growth, nutritional status, and fruiting are affected by humic acid and dry yeast. Four treatments and three replications were included in the fully randomized block design of the experiment. The following is a summary of the results that were obtained: In comparison to using the recommended dose of nitrogen (RDN) via mineral N fertilizer alone, the use of 25% mineral plus 37.5% organic and bio-form greatly increased the weight of pruning wood, the number of leaves/shoots, and the area of leaves, as well as the total chlorophyll and nutrient composition of the leaves. The usage of double form is not the cause of any notable variations in these characteristics. When compared to employing RDN from mineral sources alone, all combined fertilization treatments greatly enhanced the cluster and berry characteristics and raised the yield. According to the average of the two seasons under study, the highest levels of total soluble solids, reducing sugars, and anthocyanins were found on vines fertilized with triple form (25% N and 37.5% organic + 37.5% bio-fertilizers) at 19.3%, 16.5%, and 1.08 mg/100g, respectively. On the other hand, vines fertilized with a 100% mineral N checked treatment had the lowest values of these features, yielding, on average, 17.5%, 14.8%, and 0.96 mg/100g over the two seasons under study, respectively. The aforementioned findings clearly show that the vegetative growth, production, and berry quality were all enhanced by double or triple form. It also decreased pollutants in the environment and production expenses.