Impact of aeroponic cultivation and plant growth regulators on the biochemical composition of grapevine leaves

Background: Grapevine (Vitis vinifera L.) is a globally important perennial fruit crop, renowned for its economic value and cultural significance. Grape leaves, while often underappreciated, play a vital role in culinary traditions and are valued for their cultural, nutritional, and health benefits. However, the availability of grape leaves is constrained by viticulture practices and chemical treatments that prioritize fruit production over leaf harvesting. This study seeks to compare the biochemical characteristics of grapevine leaves from the cultivar 'Deghin Yerevani' grown from virus-free, tissue-cultured plants under aeroponic and soil conditions within a greenhouse. Objective: To evaluate the impact of aeroponic versus soil-based cultivation and the application of specific growth regulators on the biochemical composition and nutrient content of 'Deghin Yerevani' grapevine leaves, with the goal of optimizing conditions for high-quality leaf production. Materials and Methods: This study, conducted from 2021 to 2023 at the Scientific Center of Agrobiotechnology, ANAU, utilized virus-free in vitro plants of Vitis vinifera L. cv. 'Deghin Yerevani', sourced from the National Grape Field Collection. Plants were cultured in four treatment groups with varying growth media compositions: PGR-free, with Indole-3-acetic acid (IAA), with IAA and Gibberellic acid (GA₃), and with IAA, GA₃, and 6-Benzylaminopurine (BAP). Post-culturing, plants were transferred to either an aeroponic system, which used a misting cycle and maintained controlled environmental conditions, or to a greenhouse with a defined soil mix and monitored moisture levels. Both systems operated for 8 weeks, with each treatment replicated three times. Chlorophylls a and b, ascorbic acid, sugars, and macro- and micronutrient contents were analyzed, and statistical significance was determined using standard error and Student’s t-test (p < 0.05). Results: Grapevine leaves from 'Deghin Yerevani' plants grown in aeroponic systems exhibited significantly higher chlorophyll a, chlorophyll b, and total chlorophyll compared to those grown in soil. Growth regulators, particularly IAA, GA3, and BAP, enhanced chlorophyll content, sugar levels, and Vitamin C across both cultivation methods. Aeroponic systems showed superior results with increased sugar content (5.7 g/100g) and Vitamin C (20.4 mg/100g) compared to soil-based cultivation. Nutrient analysis revealed higher levels of nitrogen, phosphorus, potassium, calcium, and magnesium in aeroponics. Overall, growth regulators and aeroponic cultivation improved the biochemical and nutrient profiles of grapevine leaves. Conclusion: The study demonstrated that aeroponic cultivation and the application of growth regulators significantly enhanced the biochemical composition of grapevine leaves. Higher levels of chlorophyll, sugar, and Vitamin C, along with improved nutrient content, were observed in aeroponic systems compared to soil-based cultivation. These findings underscore the benefits of aeroponics and growth regulators in optimizing grapevine leaf quality, suggesting potential for improved yield and nutritional value in grapevine production. Keywords: 'Deghin Yerevani', grapevine, in vitro propagation, functional foods, Aeroponic Cultivation, Plant Growth Regulators