Some parameters of hydroponic and soil Rhubarb cultivated in the Ararat Valley of Armenia

Abstract

Background: Today, the rhubarb plant is selectively included in the diet. Rhubarb juice offers a unique flavor with a surprising range of potential health benefits. Rhubarb is rich in antioxidants, particularly anthocyanins, the pigments responsible for its red hue. These antioxidants are believed to possess anti-inflammatory and anti-bacterial properties, potentially aiding in the fight against various health concerns. Rhubarb juice is an excellent source of vitamins C, and K, crucial for bone health and blood clotting, and also contains vitamin A, contributing to healthy skin and vision.  Context and purpose of this study: to investigate for the first time the cultivation of rhubarb (Rheum rhabarbarum) in the Ararat Valley of Armenia in both hydroponic and soil conditions. The research focuses on identifying the optimal growth period to maximize key quality indicators of rhubarb stalks and juice for food and medicinal applications: Brix value, juice density, total titratable acidity, and vitamin C content. Results: Hydroponic cultivation significantly (by three folds) increased the fresh weight of rhubarb petioles (stalks) compared to soil plants. The maximum accumulation of vitamin C in hydroponic plants was observed at the beginning (June) and end (September) of the growing season (19.4 and 17.3 mg%) respectively. However, there was not a significant difference in vitamin C content during July and August (14.3 and 14.0 mg% respectively). Soil plants showed the highest accumulation of vitamin C in September (41.5 mg%), exceeding the values in June by 1.2 times and from July to August by 1.5 times. Total titratable acidity showed seasonal variations: the highest acidity (1.2 to 1.3-fold higher) of hydroponic rhubarb juice was observed in July compared to other months. Soil-grown rhubarb reached peak acidity at the beginning of the growing season (approximately 1.2 times higher than in other months). The Brixo value and juice density peaked in July for hydroponic rhubarb and in August for soil rhubarb. Conclusion: This study highlights the potential of hydroponics for maximizing rhubarb yield and potentially influencing the vitamin C content and acidity profile throughout the growing season in Armenia. The results of further research could be used to optimize nutrient composition and environmental parameters for even greater control over rhubarb quality for food and medicinal purposes. Keywords: Vitamin C, Total titratable acidity, Brixo, Juice density