Document Type : Research Paper

Authors

• Razieh Pourbeirak ¹
• Farhad Mohajeri ¹
• Mehdi Madandoust ¹
• Abolfath Moradi ²

¹ Department of Agriculture, Fa. C, Islamic Azad University, Fasa, Iran

² Department of Soil and Water Research, Fars Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education, and Extension Organization (AREEO), Shiraz, Iran

Abstract

Objective: This study aimed to evaluate the role of bio–mineral nutrition management in enhancing drought tolerance, maintaining seed yield, and stabilizing physiological and biochemical indices of quinoa under varying irrigation levels.
Method: The experiment was conducted over two consecutive growing seasons (2021–2022 and 2022–2023) using a factorial split-plot arrangement based on a randomized complete block design with three replications. Irrigation levels (100%, 75%, and 50% of field capacity) were considered the main factor, while factorial combinations of biofertilizers (no inoculation, Nitroxine, and BioPhosphor) and foliar micronutrient sprays (control, iron, and zinc) were considered sub-factors. Measured traits included seed yield, harvest index, proline content, total carbohydrates, soluble protein, and catalase enzyme activity. In addition, soil physical and chemical properties were periodically monitored to ensure the accuracy of treatment effects and to assess potential long-term improvements in soil fertility and biological activity. Statistical analyses were performed using combined ANOVA across years, and mean comparisons were conducted by LSD at 5% probability level. 
Findings: The results showed that reduced irrigation caused a significant decline in grain yield; under 75% field capacity irrigation, grain yield decreased by 25%, and under 50% field capacity irrigation, it decreased by 44% compared to full irrigation. The combination of Nitroxin with iron exhibited the highest yield in both years, reaching 2859 kg ha⁻¹ under full irrigation (an increase of 22% compared to the control) and 1583 kg ha⁻¹ under severe water deficit (an increase of 30% compared to the control). Harvest index also decreased under water limitation, but the BioPhosphor+ iron treatment showed the greatest stability, maintaining 13.35% under 50% field capacity compared to 18.27% in the control. Proline accumulation increased under drought stress; however, Nitroxine + iron application reduced it by up to 41% compared to the control. Additionally, BioPhosphor enhanced total carbohydrates by 37%, and Nitroxine increased leaf soluble protein by 41% under severe drought. Catalase activity increased due to reduced soil moisture, but biofertilizer inoculation, particularly with Nitroxine, moderated this increase by approximately 39%. These findings collectively highlight the synergistic role of microbial inoculants and micronutrient application in maintaining plant metabolic efficiency and reducing oxidative damage during water scarcity.
Conclusions: Overall, the findings suggest that integrated bio–mineral nutrition management, especially the combination of Nitroxine and iron, improves the nutritional and physiological status of quinoa, mitigates oxidative stress, and preserves drought-adaptive compounds, thereby significantly enhances yield and stability under water-limited condition. This strategy can be recommended as a sustainable and environmentally compatible approach to improve water-use efficiency and maintain quinoa productivity in arid and semi-arid regions. Moreover, such integrative management practices contribute to long-term soil health improvement, reduced dependence on chemical fertilizers, and enhanced resilience of cropping systems to climate variability.

Keywords

• BioPhosphor
• Irrigation Regimes
• Micronutrients
• Nitroxine
• Proline‎