Green spinach is a widely consumed vegetable with high nutritional value, including iron, vitamin C, protein, and carbohydrates. However, there has been a decrease in green spinach productivity in Indonesia due to suboptimal cultivation techniques, low seed quality, and limited use of agricultural technology. To address this, agricultural intensification is necessery, such as the application of natural plant growth regulators (PGR). This study aimed to compare the effects of red onion and shallot extract as natural PGR on the growth of green spinach plants (including plant height, number of leaves, leaf circumference), wet biomass, total phenolic content, and antioxidant activity. Different concentrations of PGR (0%, 15%, 30%, 45%) were used, and the results were statistically analyzed using SPSS software with analysis of variance (ANOVA) and futher tested with the Duncan Multiple Range Test (DMRT) at a 5% significance level. The findings indicated that the use of red onion and shallot extracts as a natural PGR could enhance plant height, number of leaves, leaf circumference, wet biomass, total phenolic content, and antioxidant activity of green spinach plants. Notably, the application of shallot extract at a concentration of 45% yielded the most favorable results across all observed parameters.
Keywords: Plant growth regulator, red onion extract, shallot extract, green spinach plant, plant growth, total phenolic, antioxidant activity.