Effects of Biostimulants on Growth and Biochemical Composition of Amaranthus dubius

Abstract

The study aimed to evaluate the effects of different biostimulants on the growth, yield, biochemical properties, and economic viability of Amaranthus dubius and identify the most effective biostimulant or combinations for improving crop performance and profitability while providing an eco-friendly alternative to traditional practices.The experiment was arranged in a randomized block design over two seasons with 11 treatments involving single or combined applications of Moringa leaf extract (MLE), seaweed extract (SWE), salicylic acid (SA), and humic acid (HA). The statistical evaluation of the datasets used one-factor analysis utilizing OPSTAT software obtaining relevant results at a 5% significance level against values of F-test. Key results revealed that T3 (SWE 6%) and T8 (HA 0.4%) were the most cost-effective treatments, with benefit-cost ratios (B:C) of 2.44 and 2.30, respectively, driven by high yields (163.73 kg/5 cents and 155.23 kg/5 cents) and moderate input costs. While T11 (combined MLE 3% + SWE 8% + SA 200 ppm + HA 0.4%) exhibited superior biochemical performance—highest chlorophyll a (3.173 mg/g), total chlorophyll (3.387 mg/g), carotenoids (1.391 mg/g), and leaf/stem ratio (1.07)—its B:C ratio (1.35) was suboptimal due to high costs. T10 (combined MLE 2% + SWE 6% + SA 100 ppm + HA 0.2%) showed balanced performance, with a B:C ratio of 1.88 and significant yield (147.66 kg/5 cents). Physiological parameters highlighted T10 and T11 as top performers in membrane stability (42.63% and 47.60%, respectively) and oxalic acid reduction (0.0218 mg/g in T10). Growth metrics identified T3 and T7 (HA 0.2%) as leaders in leaf area (62.03 mm²) and root length (9.23 cm). Statistical analysis grouped treatments into distinct economic and biochemical efficacy tiers, with T3 and T8 outperforming others in profitability. The study underscores the potential of SWE 6% and HA 0.4% as economical biostimulants for enhancing Amaranthus dubius growth, yield, and productivity.