Examining the Optimal Amount of Moringa Leaf Extract to Improve the Morphological and Inner Quality of Cabbage (Brassica oleracea var. capitata)

Abstract

Moringa leaves contain a proper amount of antioxidants, amino acids, vitamins, hormones, macronutrients, and micronutrients. Therefore, it is applied as a natural, inexpensive, and simple-to-make biostimulant to boost nutritional value and growth parameters in a variety of plants. The main purpose of this study is to determine the optimal concentration of Moringa oleifera L. leaf extract (MLE) as an effective biostimulant to improve nutritional and physical quality in cabbage (Brassica oleracea var. capitata). To do this, three concentrations of MLE (6, 8, and 10%) were foliar sprayed to the plant leaves at a rate of 25 mL plant−1 for every two weeks from transplantation till harvest, while control plants (Ø) were sprayed with distilled water only. Our results show that MLE greatly increased cabbage growth, nutrient content, pigment content, and nutrient absorption, while a high concentration of 10% MLE could also significantly reduce nitrate content in cabbage leaves. In comparison to the control plants, sprays of 6%, 8%, and 10% MLE reduced nitrate content by 23%, 14%, and 12%, respectively. However, the lowest nitrate content was found for the plants sprayed with 6% MLE. Except for the dry matter, all the growth parameters, mineral content, and pigment content were significantly higher after spraying with 10% MLE, while better vitamin C and lower nitrate were found in the plants treated with 6% MLE. A Pearson correlation reveals that head weight has a positive correlation with head diameter, head height, chlorophyll a, and carotenoids at $p$ levels of 0.01 and a positive correlation with chlorophyll b and vitamin C at $p$ levels of 0.05. Vitamin C and dry matter, on the other hand, had a negative connection with nitrate content.