Akbar Aliverdi; Samira Karami
Abstract
Introduction
Guar forms a weak symbiotic relationship with some strains of bradyrhizobium bacteria, making it important to strengthen this symbiosis. Research on other legumes suggests ...
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Introduction
Guar forms a weak symbiotic relationship with some strains of bradyrhizobium bacteria, making it important to strengthen this symbiosis. Research on other legumes suggests that soil application of silicates can enhance legume-bacterium symbiosis, leading to improved yields due to increased silicon uptake. However, industrial production of silicates is costly, prompting interest in silicate-dissolving bacteria, which can solubilize native or applied silicates in the soil. These bacteria have been shown to improve silicon and nutrient uptake, resulting in better plant growth and yield. This study aims to investigate the impact of soil-applied silicates (Na2SiO3, K2SiO3, Ca2SiO3, and Mg2SiO3) and silicate-dissolving bacteria on the guar-bacterium symbiosis, plant growth, and yield.
Materials and Methods
A pot experiment was performed at Bu-Ali Sina University in 2022 using a two-factor factorial (2×5) design in a completely randomized setup with 10 replications. The first factor included five silicate treatments: control, Na2SiO3, K2SiO3, Ca2SiO3, and Mg2SiO3 (applied at 100 mg/kg of soil). The second factor involved soil inoculation with a commercial silicate-dissolving bacterium at two levels: 0 and 10 ml/kg of soil. Sixty days after planting, half of the plants were harvested to measure shoot and root dry weight, nodule number and dry weight, shoot and root nitrogen content, and shoot silicon content. At pod maturity 80% brown pods), the remaining plants were harvested to measure 100-seed weight, seed yield per plant, and seed gum content.
Results and Discussion
All traits, except seed gum content, were significantly affected by the main and interaction effects of silicate application and bacterial inoculation. Without silicate application, silicate-dissolving bacteria increased: nodule number (34%), nodule dry weight (75%), shoot dry weight (42%), silicon content (16%), shoot nitrogen content (15%), root nitrogen content (41%), and seed yield per plant (25%). However, root dry weight and 100-seed weight were unaffected by bacterial inoculation. Without bacterial inoculation, application of any silicate significantly increased shoot silicon content. Moreover, the synergistic effect of silicates and silicate-dissolving bacteria further increased shoot silicon content. The highest silicon content (550.1 mg/kg of dry weight) was recorded with the combined application of K2SiO3 + silicate-dissolving bacteria. Although the seed gum content remained unaffected, the observed increase in seed yield per plant indicates greater gum production potential at the whole-plant level.
Conclusion
The synergistic interaction between silicates and silicate-dissolving bacteria enhances the efficiency of silicate use in guar cultivation. This approach holds promise for improving guar yields without affecting seed gum content. The increase in seed yield directly translates to higher gum production per plant, making this strategy beneficial for guar farming systems.
