Impact of different Rhizobium isolates on yield attributes, yield and post-harvest soil available nitrogen in chickpea (Cicer arietinum L.)

Introduction

Chickpea (Cicer arietinum L.), commonly known as Bengal gram or Chana, is a nutrient-rich Rabi pulse crop belonging to the Fabaceae family, with India leading global production. Excessive dependence on synthetic nitrogen fertilizers in chickpea cultivation poses economic and environmental challenges, highlighting the importance of biological nitrogen fixation (BNF) as a sustainable alternative. In legumes, symbiotic association with Rhizobium, Bradyrhizobium, or Mesorhizobium converts atmospheric nitrogen into plantavailable forms, improving soil fertility, reducing fertilizer use, and benefiting subsequent crops. In chickpea, Mesorhizobium species form root nodules that enhance nitrogen availability and contribute to soil health through deep rooting and canopy shading. However, the efficiency of BNF is influenced by soil moisture, temperature, pH, salinity, nutrient availability, and pesticide use, which affect rhizobial survival and infectivity. Therefore, selecting efficient, stress-tolerant rhizobial strains is crucial for maximising nitrogen fixation, improving yield, and promoting sustainable agricultural practices.

Materials and Methods

A field experiment entitled "Evaluation of different Rhizobium isolates of chickpea (Cicer arietinum L.) under field condition responsible to biological nitrogen fixation" was conducted during Rabi 2024-25 at the Instructional Farm, BTC College of Agriculture and Research Station, Bilaspur, Chhattisgarh. The site falls under the Chhattisgarh plains, with a sub-humid climate, annual rainfall of 1200-1400 mm, and clay loam soil (pH 6.9, EC 0.31 dS m⁻¹, organic carbon 0.48%, available N 242.97 kg ha⁻¹, P₂O₅ 12.42 kg ha⁻¹, K₂O 286.36 kg ha⁻¹).The experiment was laid out in a Randomized Block Design with 12 treatments (Table 1) and three replications, using chickpea variety Indira Chana-1. Treatments included recommended dose of fertiliser (20:50:30 N:P₂O₅:K₂O kg ha⁻¹) alone and in combination with different Rhizobium isolates, along with control. Each plot measured 10.08 m² net area with 30 × 10 cm spacing. Standard agronomic practices were followed, including seed treatment with thiram and Rhizobium culture, two irrigations, nipping at 30-40 DAS, prepre-emergence weed control, and pest management.

Observations recorded included plant growth parameters, nodulation traits, yield attributes, grain and straw yield and soil available nitrogen.

Results and Discussion

Yield attributes

The data pertaining to yield attributes and yield of chickpea are presented in Table 2.

Number of pods plant -1

The number of pods per plant varied significantly among treatments, ranging from 41. [5] reported that combining RDF with effective Rhizobium isolates significantly enhances nodulation and assimilate allocation, thereby increasing pod number. Choudhary and Sharma (2021) [6] also found similar trends in chickpea and lentil with native Rhizobium strains. [7] showed that Rhizobium inoculation improves pollen viability and ovule fertilization in legumes, leading to higher seed numbers. Yadav et al.

Number of seeds pod

(2020) [8] also emphasized that co-application of RDF and suitable Rhizobium strains significantly boosts yield components in pulses.

The test weight ranged from 181.51 g (T₁-Control) to 186.25 g (T₉-RDF + Rhizobium Local Isolate 21). The highest value was recorded in T₉ (186.25 g), followed closely by T₃ (186.08 g) and T₈ (185.77 g). However, the differences were statistically non-significant, indicating that the treatments did not cause a notable variation in seed weight. The lowest test weight was observed in T₁ (181.51 g), suggesting a marginal improvement due to treatment, though not statistically proven. Test weight is a relatively stable trait, often less responsive to microbial treatments than yield attributes. According to Kumar et al. (2020) [9] , test weight may show minor changes under biofertilizer application, but these are often non-significant. Rana et al. (2018) [10] also noted that test weight in legumes is influenced more by genotypic factors than by microbial inoculants.

Grain yield (q ha -1 ) Grain yield varied significantly among treatments, ranging from 9.71 q ha⁻¹ (T₁-Control) to 17.09 q ha⁻¹ (T₉-RDF + Rhizobium Local Isolate 21). The highest grain yield in T₉ was significantly superior to the treatments T 1 , T 2 and T 11 and statistically at par with rest all treatments. The lowest grain yield was observed in Control (T₁) 9.71 q ha⁻¹, indicating that nutrient application and bio-inoculants significantly improve yield performance.Grain yield in legumes is known to increase with effective Rhizobium inoculation due to enhanced nodulation and nitrogen fixation. Singh et al. (2021) [3] reported that combining RDF with effective Rhizobium isolates significantly increased chickpea productivity. Similarly, Yadav and Meena (2020) [8] found that local isolates often outperform state checks due to better adaptation and symbiotic efficiency, resulting in increased grain yield.

Straw yield also showed a significant response to the treatments, ranging from 15.09 q ha⁻¹ (T₁-Control) to 24.75 q ha⁻¹ (T₉). The highest straw yield in T₉ (24.75 q ha⁻¹) was significantly superior to the T 1 , T 2 and T 11 and statistically at par with rest all treatments. RDF alone (T₂) recorded 21.24 q ha⁻¹, indicating moderate improvement compared to the control but lower than bio-inoculated treatments. The lowest straw yield in T₁ (15.09 q ha⁻¹) reflects the baseline yield without nutrient or microbial input. Straw yield benefits from improved vegetative growth and biomass accumulation, both of which are supported by nitrogen fixation from effective Rhizobium strains. Chaudhary et al.

(2019) [11] noted that inoculation of legumes with compatible Rhizobium strains increased shoot biomass and hence straw yield. Sharma and Rana (2018) [10] also reported similar increases in haulm yield due to improved nutrient uptake and photosynthetic activity.

As shown in [1] and Sharma et al.

(2020) [2] , who reported that RDF integrated with efficient or locally adapted Rhizobium strains significantly improves soil nitrogen status in chickpea.

References

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