Document Type : Research Paper
Author
DEPARTMENT of agronomyDepartment of Agronomy, Malekan Branch, Islamic Azad University, Malekan, Iran.
Abstract
Objective: The objective of the present study was to evaluate whether foliar application of plant-growth-promoting bacteria and vitamins can enhance growth, physiology, and yield of quinoa while reducing chemical inputs.
Methods: A field experiment (2023–2024) was conducted in a split-plot arrangement within a randomized complete-block design with three replications. Factor A (bacteria strains) included: no bacteria, Pseudomonas fluorescens, Bacillus subtilis, and a combination of both strains. Factor B (vitamin concentrations) included 2, 4, and 6 g/L. Foliar sprays were applied twice during the growing season at two-week intervals, during the cooler evening hours (establishment and two weeks later). Measured traits included plant height, leaf area index (LAI), chlorophyll index, seed yield per plant, levels of cytokinin, auxin, gibberellin, seed protein, leaf soluble carbohydrate content, and total antioxidant capacity.
Results: ANOVA revealed significant effects of foliar bacteria and vitamin treatments on several traits, including plant height, LAI, phytohormone contents (auxin, cytokinin, gibberellin), chlorophyll index, and grain yield. The tallest plants reached about 110 cm with Bacillus subtilis, representing a 12.2% increase over the control. Vitamin applications, particularly at 150 mg/L, increased plant height by approximately 6.8% and improved LAI. Foliar treatments also elevated leaf auxin and cytokinin concentrations, with the highest auxin observed under Bacillus subtilis plus 150 mg/L vitamins (≈81% increase). Combined bacterial and vitamin treatments generally outperformed single applications for chlorophyll synthesis and grain yield. Grain yield increased by about 23.15% with the Bacillus subtilis+ 150 mg/L vitamin treatment. Grain protein content was highest with Bacillus subtilis in year one.
Conclusion: Foliar application of growth-promoting bacteria (B. subtilis and P. fluorescens) in combination with vitamins beneficially affected quinoa growth, physiology, and yield, with the combination often outperforming individual treatments. The Bacillus subtilis and 150 mg/L vitamin regime most consistently enhanced plant height, LAI, hormone balance, chlorophyll content, grain yield, and grain protein. These results suggest that integrating bacterial and vitamin foliar sprays can reduce reliance on chemical inputs while improving quinoa productivity under field conditions.
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