Evaluation of Plant Growth Promotion by Rhizobium-Inoculated Biofertilizer in Leguminous and Non-Leguminous Crops

Abstract

Rhizobium species are widely recognized for their role in symbiotic nitrogen fixation in leguminous crops. However, their potential to enhance growth in non-leguminous crops remains underexplored. This study evaluates the plant growth-promoting efficiency of Rhizobium-inoculated biofertilizer on Vigna radiata (Green gram) and Zea mays (Maize) under controlled conditions. Biofertilizer formulations containing Rhizobium sp. were applied at sowing, and their effects on germination, shoot and root length, fresh and dry biomass, and chlorophyll content were assessed after 30 days. Results revealed a significant improvement (p < 0.05) in all growth parameters of Vigna radiata, while non-leguminous maize showed moderate growth enhancement. ANOVA indicated significant differences between treatments, with Rhizobium-inoculated biofertilizer outperforming control and chemical fertilizers. These findings highlight the scope of Rhizobium biofertilizers as sustainable growth promoters for leguminous crops and as potential growth enhancers for non-legumes.

Introduction

1. Background

• Nitrogen (N) is vital for plant growth, but overuse of chemical N fertilizers leads to serious environmental issues (e.g., soil acidification, water pollution, greenhouse gas emissions).

• Biofertilizers like Rhizobium offer sustainable alternatives by naturally fixing nitrogen and promoting plant growth.

• Traditionally used in leguminous crops, Rhizobium is now found to have growth-promoting effects even in non-leguminous crops via mechanisms like:

  • Phytohormone production

  • Phosphate solubilization

  • Siderophore secretion

  • Disease suppression

2. Objectives of the Study

The study aimed to evaluate the effect of Rhizobium biofertilizer on:

1. Germination, growth (shoot, root, biomass), and chlorophyll content in:

   • Vigna radiata (Green gram - legume)

   • Zea mays (Maize - non-legume)

2. Comparative response between leguminous and non-leguminous crops.

3. Statistical analysis using ANOVA and Tukey’s HSD test.

3. Methodology

• Location: MIET, Meerut (Controlled conditions)

• Design: Completely Randomized Design (CRD) with 3 treatments and 5 replications per crop.

• Treatments:

  • T?: Control (no fertilizer)

  • T?: NPK chemical fertilizer

  • T?: Rhizobium inoculated biofertilizer

• Parameters Measured (30 days after sowing):

  • Germination rate

  • Shoot/root length

  • Fresh/dry weight

  • Chlorophyll content (Arnon’s method)

4. Key Results

A. Germination

• No significant difference in germination across treatments (all >90%).

• Rhizobium did not negatively affect germination.

B. Growth Parameters

• Rhizobium outperformed NPK in green gram, especially in chlorophyll content and biomass.

• In maize, Rhizobium was slightly less effective than NPK but still beneficial.

5. Statistical Analysis

• ANOVA showed significant differences (p < 0.05) among treatments for all parameters except germination.

• Tukey’s HSD confirmed Rhizobium's positive effect on both crops, especially legumes.

Conclusion

The present study demonstrated that Rhizobium inoculation significantly enhanced plant growth parameters in the leguminous crop (Vigna radiata) compared to control and was comparable to chemical fertilizer treatment. Improvements were observed in shoot and root length, biomass accumulation, and chlorophyll content, reflecting the beneficial role of symbiotic nitrogen fixation in legumes. In the non-leguminous crop (Zea mays), Rhizobium inoculation resulted in moderate but statistically significant improvements in growth attributes over the control, which can be attributed to plant growth-promoting traits such as phytohormone production, siderophore secretion, and phosphate solubilization. These findings confirm the dual role of Rhizobium as both a symbiotic nitrogen fixer in legumes and a plant growth-promoting rhizobacterium (PGPR) in non-legumes. Overall, Rhizobium-based biofertilizers offer a sustainable alternative to chemical fertilizers, reducing dependency on synthetic inputs and contributing to environmentally friendly crop production systems.

References

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Copyright

Copyright © 2025 Khusboo ., Anjali Rathi, Sonia Sharma, Subir Kumar Bose. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.