How Does the Addition of Biostimulants Affect the Growth, Yield, and Quality Parameters of the Snap Bean (Phaseolus vulgaris L.)? How Is This Reflected in Its Nutritional Value?

Recently, the use of biostimulants as natural and eco-friendly fertilizers has received increasing attention because of their efficiency in terms of improving crops’ qualitative and quantitative parameters, i.e., growth, yield, and chemical composition. We studied the effect of four biostimulants—humic acid (20 g/L), vermicompost tea (15 mL/L), moringa leaf extract (1:30 v/v), and yeast extract (5 g/L), with tap water as a control treatment—on the qualitative and quantitative characteristics of snap beans. The experiment was designed using a complete randomized block with triplicates. The results showed a significant improvement in treated plant performance (growth and yield), chlorophyll, and chemical composition compared to untreated plants. Using moringa leaf extract increased the plant height, number of leaves and branches/plant, and fresh and dry weight. Additionally, the diameter of the treated plant stems and the quality of the crop and pods were also significantly higher than those of plants treated with vermicompost or humic acid extract. It is also noted that the profile of amino acids was improved using all tested biostimulants. This leads to the conclusion that the addition of moringa leaf extract and vermicompost tea not only positively affects the qualitative and quantitative properties of snap bean but is also reflected in its nutritional value as a plant-based food.