Response of Yield, Quality, and Bioactive Constituents of Green Onion to Foliar Spraying with Moringa oleifera Leaf Extract and Yeast Extract

Abstract

HE APPLICATION of biostimulants to improve plant growth, quality, and productivity is an effective and eco-friendly field. Green onion is a widely consumed vegetable due to its nutritional content and distinctive flavor. The response of green onion growth, yield, bioactive compounds accumulation, and antioxidant activity to foliar application of moringa (Moringa oleifera) leaf extract (MLE) and yeast extract (YE), as biostimulants was investigated in the present study during 2021/2022 and 2022/2023 seasons under open field conditions. MLE (2%, 4%, and 6%) and YE (1, 2, and 3 g/L) were applied as foliar solutions. The results showed that plant height, fresh weight (FW), dry matter, yield, nutrients content, photosynthetic pigments (chlorophyll and carotenoids), bioactive compounds [ascorbic acid, total phenolics content (TPC), and total flavonoids content (TFC)], and antioxidant properties [total antioxidant capacity (TAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity (IC 50 )] exhibited a better response to specific levels of YE and MLE. When compared to chemical fertilizers, the increase in green onion yield achieved by YE and MLE was accompanied by a decrease in nitrate content and an increase in total soluble solids (TSS), pyruvic acid, and ascorbic acid. TPC was maximized with chemical fertilizers and 2 g/L of YE. However, no statistical differences were observed in the TFC, TAC, and IC 50 among treatments involving chemical fertilizers, moderate, and higher levels of MLE and YE. According to Pearson's correlation analysis, a positive correlation existed between yield and each of ascorbic acid, TPC, TFC, and TAC. The nitrate content correlated negatively with pseudo-stem length, TSS, pyruvic acid, and bioactive compounds. Conclusively, YE and MLE have the potential to make green onion farming more sustainable and resilient with high quality and high nutraceutical content, thus mitigating the need for chemical fertilizers.