Abstract
Introduction:
Groundnut productivity under low-input production systems is often constrained by poor nutrient availability and unfavorable soil physical conditions. This study evaluated the interactive effects of polythene mulching and novel native microbial inoculants on crop growth, nodulation, rhizosphere microbial abundance, and productivity under zero-fertilizer conditions.
Methods:
A two-year split-plot field study was conducted on new alluvial sandy loam soil to evaluate the interactive effects of polythene mulching and novel native microbial inoculants NRA1 (PP355674) and JCA-5 (PP809390) on rhizosphere microbial abundance and groundnut (Arachis hypogaea L. cv. TG51) productivity under zero-fertilizer conditions. Growth, nodulation, rhizosphere microbial populations, yield attributes, and productivity were evaluated.
Results:
Polythene mulching significantly enhanced vegetative growth, root biomass, nodulation, and pod yield, likely due to improved soil moisture conservation and microclimatic moderation. The Rhizobium–PSB consortium increased early nodulation (32.9 nodules plant-¹) and rhizobial abundance (47.8 × 104 CFU g-¹ soil), indicating improved symbiotic establishment. However, microbial inoculation did not significantly influence final yield despite enhancing nodulation and rhizosphere microbial abundance. At crop maturity, reduced total bacterial counts under mulching suggest possible effects of altered soil temperature, aeration, or substrate availability.
Discussion:
The findings demonstrate that polythene mulching is the primary driver of crop productivity under zero-fertilizer conditions, whereas native microbial inoculants provide complementary benefits by enhancing nodulation and rhizosphere microbial functioning. Integrating polythene mulching with provenance-adapted microbial inoculants may improve resource-use efficiency and contribute to sustainable groundnut production in low-input alluvial agroecosystems.
1 Introduction
Groundnut (Arachis hypogaea L.) productivity in the Indo-Gangetic alluvial plains is increasingly constrained by soil physical stress in addition to nutrient limitations. Rabi–summer cultivation in eastern India is characterized by elevated soil temperatures, high evaporative demand, and limited soil moisture availability, conditions that can disrupt rhizosphere processes and reduce the efficiency of biological nitrogen fixation (, ). Under such environments, crop performance depends not only on nutrient supply but also on the stability of soil–plant–microbe interactions operating under thermal and hydrological stress (, ).
Conventional intensification strategies have relied on mineral fertilizers; however, field evidence from alluvial soils indicates reduced efficiency of nutrient inputs under high-temperature conditions (, ). Fertilizer response is often limited when soil physical constraints restrict root development and microbial activity. These limitations highlight the importance of soil physical regulation as a prerequisite for efficient nutrient utilization, particularly in low-input systems (–).
Polythene mulching is a soil management practice known to influence soil temperature and moisture regimes, potentially improving root-zone conditions during early crop growth (, ). While mulching has been associated with improved crop performance, its role in regulating rhizosphere microbial abundance and symbiotic nitrogen fixation under zero-fertilizer conditions remains insufficiently understood. Soil physical modification may influence microbial establishment and activity, thereby affecting the functional expression of introduced inoculants (, ).
The performance of biological inoculants is highly strain-dependent and often inconsistent under field conditions due to ecological incompatibility and competition with native microbial populations (, ). Recent screening of native Rhizobium isolates from eastern Indian agro-ecosystems has identified strains with improved nodulation efficiency and adaptability under controlled conditions (–). However, field-scale validation of such provenance-adapted strains, particularly in combination with phosphate-solubilizing bacteria (PSB), under zero-fertilizer and stress-prone environments remains limited (–).
Phosphorus limitation in alluvial soils may constrain nodulation efficiency and symbiotic nitrogen fixation. A consortium approach combining a functionally efficient Rhizobium strain with compatible PSB may enhance early symbiotic establishment and nutrient mobilization in the rhizosphere (). However, the extent to which such biological inputs can improve crop performance under soil physical constraints remains unclear.
Therefore, the present study was conducted to evaluate the interactive effects of polythene mulching and novel native Rhizobium–PSB inoculants on groundnut productivity and rhizosphere microbial abundance under zero-fertilizer conditions. The study further aimed to assess the relative contribution of soil physical modification and microbial inoculation to crop performance under stress-prone alluvial conditions.
2 Materials and methods
2.1 Experimental site and soil characteristics
Two-year field experiment was conducted during the Rabi–summer seasons of 2014 and 2015 at the District Seed Farm (AB Block), Bidhan Chandra Krishi Viswavidyalaya, Kalyani, Nadia, West Bengal, India (23.5° N, 89.0° E; ~9.75 m amsl). The site represents the new alluvial zone of the lower Indo-Gangetic plains and experiences a subtropical humid climate.
Rabi–summer groundnut cultivation at the site is characterized by progressively increasing air and soil temperatures, frequently exceeding 40 °C during mid-to-late growth stages, along with high evaporative demand and rapid soil moisture depletion. These conditions impose constraints on root growth, nodulation, and rhizosphere microbial activity, making the site representative of stress-prone summer groundnut systems.
The soil was a sandy loam Inceptisol with near-neutral pH (6.8–7.1), moderate organic carbon (0.54–0.58%), low available nitrogen (197–214 kg ha-¹) and potassium (103–107 kg ha-¹), and medium available phosphorus (14.7–15.4 kg ha-¹). No inorganic fertilizers or organic amendments were applied in order to evaluate treatment effects under zero-fertilizer conditions.
2.2 Isolation, screening, and selection of microbial inoculants
2.2.1 Native rhizobium isolation and selection
Native Rhizobium isolates were obtained from effective nodules of healthy groundnut plants collected from the new alluvial zone during the preceding summer season. Surface-sterilized nodules were aseptically crushed and plated on Yeast Extract Mannitol Agar (YEMA) supplemented with Congo red. Fast-growing colonies were purified and subjected to morphological, biochemical, physiological, and molecular characterization.
From the initial pool, functionally superior isolates were shortlisted based on growth characteristics, stress tolerance, and nodulation efficiency in preliminary evaluations. Among these, isolate NRA1 consistently exhibited enhanced nodulation performance () and was selected for field experimentation. ().
2.2.2 Isolation of phosphate-solubilizing bacteria
Phosphate-solubilizing bacteria (PSB) were isolated from rhizosphere soils using Pikovskaya’s agar medium. Colonies producing clear halo zones were purified and evaluated for phosphate solubilization efficiency. The most efficient isolate, designated JCA-5, was identified as Priestia megaterium based on biochemical characterization and 16S rRNA gene sequencing (). ().
2.2.3 Inoculum preparation
Selected Rhizobium NRA1 and PSB JCA-5 strains were multiplied separately in liquid media and adjusted to approximately 108 CFU mL-¹. For the consortium treatment, equal volumes of both cultures were mixed immediately prior to seed inoculation.
2.3 Experimental design and treatments
The experiment was laid out in a split-plot design with four replications, with mulching treatments assigned to main plots and microbial inoculation treatments to subplots.
Main-plot treatments:
M0: No mulching.
M1: Polythene mulching (transparent UV-stabilized film, 7 µ thickness).
Sub-plot treatments:
S1: Rhizobium NRA1.
S2: PSB (Priestia megaterium JCA-5).
S3: Rhizobium NRA1 + PSB JCA-5 consortium.
Each subplot measured 3 × 4 m (12 m²). Groundnut cultivar TG51 (short-duration, Spanish bunch type) was used. Seeds were surface-sterilized, inoculated with respective cultures for 30 minutes, shade-dried, and sown at a spacing of 30 × 10 cm. No fertilizers were applied in any treatment.
2.4 Crop management
The field was prepared using conventional tillage to obtain a uniform seedbed. Polythene mulch was applied prior to sowing in designated plots. Irrigation, weed management, and plant protection measures were applied uniformly across treatments to minimize confounding effects. The crop was harvested at physiological maturity (approximately 90–95 days after emergence).
2.5 Growth, nodulation, and yield measurements
Observations were recorded at 45, 60, and 75 days after emergence (DAE) and at harvest. Five representative plants per plot were sampled.
Growth parameters included shoot length, root length, shoot dry matter, and root dry matter. Nodulation parameters included total nodules, effective nodules, and nodule dry weight.
Yield attributes included pods per plant, hundred-kernel weight, shelling percentage, and sound mature kernel percentage. Final productivity was assessed in terms of pod yield, kernel yield, haulm yield, and harvest index.
2.6 Rhizosphere microbial enumeration
Rhizosphere soil samples (0–15 cm) were collected at 45 days after emergence and at harvest. Soil adhering to the root surface was gently collected after uprooting plants. Serial dilution and standard plate count techniques were used to enumerate total bacteria, Rhizobium, and phosphate-solubilizing bacteria (PSB) using selective media.
Microbial counts were expressed as colony-forming units (CFU) per gram of soil. The method is culture-dependent and therefore represents only the cultivable fraction of the rhizosphere microbial population.
2.7 Statistical analysis
Data from the two years (2014 and 2015) were pooled after testing for homogeneity of variance. Analysis of variance (ANOVA) appropriate for a split-plot design was performed, with mulching (M) as the main-plot factor and microbial inoculation (S) as the sub-plot factor, with four replications.
The statistical model included the effects of blocks, mulching (M), microbial inoculation (S), and their interaction (M × S). Separate error terms were used for testing main-plot and sub-plot effects: mulching was tested against the block × mulching interaction, while microbial inoculation and the interaction (M × S) were tested against the residual error.
The null hypotheses tested were: (i) no effect of mulching (H0: M0 = M1), (ii) no effect of microbial inoculation (H0: S1 = S2 = S3), and (iii) no interaction between mulching and microbial inoculation (H0: M × S = 0).
Treatment means were compared using Fisher’s least significant difference (LSD) test at P ≤ 0.05.
3 Results
3.1 Crop growth and biomass responses
The effects of mulching and microbial inoculation on vegetative growth parameters of groundnut are presented in Table 1, Figure 1.
Table 1
| Treatment | Shoot length (cm) | Root length (cm) | ||||
|---|---|---|---|---|---|---|
| 60 DAE | 75 DAE | Harvest | 60 DAE | 75 DAE | Harvest | |
| M0S1 | 27.5 | 39.2 | 40.8 | 12.8 | 13.1 | 13.4 |
| M0S2 | 29.0 | 40.1 | 42.3 | 14.6 | 14.9 | 15.1 |
| M0S3 | 30.7 | 41.3 | 44.2 | 15.0 | 15.9 | 16.2 |
| M1S1 | 36.7 | 44.1 | 46.1 | 16.0 | 16.6 | 16.9 |
| M1S2 | 38.0 | 43.7 | 47.4 | 15.8 | 16.9 | 17.2 |
| M1S3 | 38.7 | 44.7 | 48.9 | 16.1 | 17.1 | 17.4 |
| Main effects | ||||||
| Factor | Shoot length (cm) | Root length (cm) | ||||
| 60 DAE | 75 DAE | Harvest | 60 DAE | 75 DAE | Harvest | |
| Mulching (M) | ||||||
| M0 (without) | 29.1 | 40.2 | 42.4 | 14.2 | 14.7 | 14.9 |
| M1 (with) | 37.8 | 44.2 | 47.5 | 16.0 | 16.9 | 17.2 |
| CD (P = 0.05) | 0.49 | 2.35 | 1.78 | NS | NS | NS |
| Inoculant (S) | ||||||
| S1 (Rhizobium) | 32.2 | 41.6 | 43.5 | 14.4 | 14.9 | 15.0 |
| S2 (PSB) | 33.5 | 41.9 | 44.9 | 15.2 | 15.9 | 16.2 |
| S3 (Consortium) | 34.7 | 43.0 | 46.6 | 15.5 | 16.5 | 16.9 |
| CD (P = 0.05) | 1.18 | 2.27 | NS | 0.39 | NS | 0.80 |
| Interaction (M × S) | NS | NS | NS | NS | NS | NS |
Effect of mulching and microbial inoculation on vegetative growth of groundnut.
M0, without mulching; M1, polythene mulching.
S1, Rhizobium; S2, phosphate-solubilizing bacteria (PSB); S3, Rhizobium + PSB consortium.
Values are pooled means over two years (2014–2015) with four replications.
DAE, days after emergence.
CD, critical difference at P = 0.05; NS, not significant.
Figure 1
Shoot and root growth increased progressively with crop age under all treatments. Polythene mulching significantly enhanced shoot length at all growth stages. Pooled shoot length under mulching was 37.8 cm at 60 DAE, 44.2 cm at 75 DAE, and 47.5 cm at harvest, compared to 29.1, 40.2, and 42.4 cm, respectively, under non-mulched conditions. Root length was also higher under mulched conditions, although the differences were not statistically significant at later stages.
Root dry matter increased up to 75 DAE and declined slightly at harvest across treatments. Polythene mulching significantly increased root biomass at later stages. Shoot dry matter increased continuously up to harvest and was consistently higher under mulched conditions.
Microbial inoculation had moderate effects on growth parameters. The consortium treatment (Rhizobium + PSB) recorded relatively higher shoot length and biomass compared to individual inoculants, although differences were not always statistically significant. No significant interaction between mulching and microbial inoculation was observed for growth parameters.
3.2 Root biomass and nodulation
The effects of mulching and microbial inoculation on root biomass and nodulation are presented in Table 2, Figure 2.
Table 2
| Treatment | Total nodules (plant-¹) | Effective nodules (plant-¹) | ||
|---|---|---|---|---|
| 60 DAE | 75 DAE | 60 DAE | 75 DAE | |
| M0S1 | 63.0 | 53.0 | 24.0 | 41.0 |
| M0S2 | 56.3 | 54.8 | 17.0 | 13.8 |
| M0S3 | 59.1 | 54.8 | 35.5 | 18.8 |
| M1S1 | 66.1 | 71.2 | 27.8 | 32.5 |
| M1S2 | 63.9 | 65.2 | 23.8 | 11.3 |
| M1S3 | 68.1 | 67.4 | 30.3 | 15.5 |
| Main effects | ||||
| Factor | Total nodules (plant-¹) | Effective nodules (plant-¹) | ||
| 60 DAE | 75 DAE | 60 DAE | 75 DAE | |
| Mulching (M) | ||||
| M0 (without) | 59.5 | 54.2 | 25.5 | 17.4 |
| M1 (with) | 66.1 | 68.0 | 27.3 | 19.2 |
| CD (P = 0.05) | 2.89 | 3.16 | NS | NS |
| Inoculant (S) | ||||
| S1 (Rhizobium) | 64.6 | 62.1 | 25.9 | 36.7 |
| S2 (PSB) | 60.1 | 60.0 | 20.4 | 12.5 |
| S3 (Consortium) | 63.6 | 61.1 | 32.9 | 17.2 |
| CD (P = 0.05) | NS | NS | 2.05 | 2.03 |
| Interaction (M × S) | NS | NS | 5.39 | 5.97 |
Effect of polythene mulching and microbial inoculation on total and effective nodulation of groundnut at different growth stages.
M0, without mulching; M1, with polythene mulching.
S1, Rhizobium; S2, phosphate-solubilizing bacteria (PSB); S3, Rhizobium + PSB consortium.
Values represent pooled means over two years (2014–2015).
DAE, days after emergence.
CD, critical difference at P = 0.05; NS, not significant.
Nodulation parameters were recorded up to 75 DAE only.
Figure 2
Root dry matter increased up to 75 DAE and declined slightly at harvest. Polythene mulching significantly enhanced root biomass at 75 DAE and harvest compared to non-mulched conditions.
Total nodules per plant increased from 45 DAE to 60 DAE and showed variable trends at 75 DAE. Polythene mulching significantly increased total nodulation across growth stages. However, its effect on effective nodules was not statistically significant.
Microbial inoculation did not significantly influence total nodule number but significantly affected effective nodules. The consortium treatment recorded higher effective nodules at 60 DAE, while Rhizobium alone showed relatively higher values at early stages.
Nodule dry weight increased with crop age and was higher under mulched conditions. Significant interaction between mulching and microbial inoculation was observed for effective nodules and nodule dry weight at certain growth stages.
Nodulation parameters were recorded up to 75 DAE only.
3.3 Yield attributes and productivity
The effects of mulching and microbial inoculation on yield attributes and productivity of groundnut are presented in Table 3, Figure 3.
Table 3
| Treatment | Pods plant-¹ | Pod dry weight (g plant-¹) | Shelling (%) | Sound mature kernel (%) | 100-kernel weight (g) | Haulm yield (kg ha-¹) | Harvest index (%) |
|---|---|---|---|---|---|---|---|
| M0S1 | 10.7 | 7.9 | 66.3 | 79.8 | 42.5 | 1725 | 41.6 |
| M0S2 | 10.3 | 7.6 | 66.0 | 80.1 | 43.0 | 1628 | 41.2 |
| M0S3 | 12.7 | 9.4 | 66.9 | 78.9 | 43.2 | 1730 | 41.5 |
| M1S1 | 12.9 | 10.1 | 68.1 | 79.2 | 44.1 | 1982 | 42.0 |
| M1S2 | 14.1 | 12.1 | 67.4 | 80.9 | 45.0 | 2074 | 42.6 |
| M1S3 | 16.0 | 11.9 | 67.1 | 81.3 | 45.6 | 2276 | 43.8 |
| Main effects | |||||||
| Factor | Pods plant-¹ | Pod dry weight (g plant-¹) | Shelling (%) | Sound mature kernel (%) | 100-kernel weight (g) | Haulm yield (kg ha-¹) | Harvest index (%) |
| Mulching (M) | |||||||
| M0 (without) | 11.2 | 8.3 | 66.4 | 79.6 | 42.9 | 1695 | 41.4 |
| M1 (with) | 14.4 | 11.4 | 67.5 | 80.5 | 44.9 | 2111 | 42.8 |
| CD (P = 0.05) | 1.97 | NS | NS | NS | 1.24 | 229.29 | 1.03 |
| Inoculant (S) | |||||||
| S1 (Rhizobium) | 11.8 | 9.1 | 67.3 | 79.5 | 43.4 | 1854 | 41.8 |
| S2 (PSB) | 12.2 | 9.9 | 66.8 | 80.5 | 44.0 | 1852 | 41.9 |
| S3 (Rhizobium + PSB) | 14.3 | 10.7 | 67.0 | 80.2 | 44.5 | 2004 | 42.6 |
| CD (P = 0.05) | NS | NS | NS | NS | NS | NS | NS |
| Interaction (M × S) | NS | NS | NS | NS | NS | NS | NS |
Effect of polythene mulching and microbial inoculation on yield attributes, haulm yield and harvest index of groundnut under zero-fertilizer conditions.
M0, without mulching; M1, with polythene mulching.
S1, Rhizobium; S2, phosphate-solubilizing bacteria (PSB); S3, Rhizobium + PSB consortium.
Values represent pooled means over two years (2014–2015).
CD, critical difference at P = 0.05; NS, not significant.
Experiments were conducted under rainfed zero-fertilizer conditions.
Figure 3
Polythene mulching significantly improved yield attributes and productivity. Pods per plant, hundred-kernel weight, pod yield, and kernel yield were significantly higher under mulched conditions. Pod yield increased from 1207 kg ha-¹ in non-mulched plots to 1599 kg ha-¹ under mulching. Kernel yield showed a similar trend.
Haulm yield was also higher under mulched conditions. Harvest index increased modestly but significantly under mulching.
Microbial inoculation did not significantly influence yield attributes or productivity, although the consortium treatment showed numerically higher values. No significant interaction between mulching and microbial inoculation was observed for yield parameters.
3.4 Rhizosphere microbial populations
The effects of mulching and microbial inoculation on rhizosphere microbial populations are presented in Table 4, Figure 4.
Table 4
| Treatment | Total bacteria (×105 CFU g-¹ fresh soil) | Rhizobium population (×104 CFU g-¹ fresh soil) | PSB population (×10³ CFU g-¹ fresh soil) |
|---|---|---|---|
| M0S1 | 41.2 | 10.2 | 10.7 |
| M0S2 | 38.6 | 11.8 | 11.3 |
| M0S3 | 43.7 | 13.4 | 12.1 |
| M1S1 | 32.8 | 10.4 | 10.6 |
| M1S2 | 29.0 | 11.2 | 12.8 |
| M1S3 | 39.0 | 12.8 | 12.1 |
| Main effects | |||
| Factor | Total bacteria (×105 CFU g-¹ fresh soil) | Rhizobium population (×104 CFU g-¹ fresh soil) | PSB population (×10³ CFU g-¹ fresh soil) |
| Mulching (M) | |||
| M0 (without mulching) | 41.2 | 11.8 | 11.3 |
| M1 (with mulching) | 33.6 | 11.5 | 11.8 |
| CD (P = 0.05) | 5.66 | NS | NS |
| Inoculant (S) | |||
| S1 (Rhizobium) | 37.0 | 10.3 | 10.6 |
| S2 (PSB) | 33.8 | 11.5 | 12.1 |
| S3 (Rhizobium + PSB consortium) | 41.4 | 13.1 | 12.1 |
| CD (P = 0.05) | NS | NS | 8.13 |
| Interaction (M × S) | NS | NS | NS |
Effect of polythene mulching and microbial inoculation on rhizosphere microbial populations of groundnut at harvest.
M0, without polythene mulching; M1, with polythene mulching.
S1, Rhizobium (NRA1; GenBank accession PP355674); S2, phosphate-solubilizing bacteria (PSB; JCA-5; GenBank accession PP809390); S3, Rhizobium + PSB consortium.
Values represent pooled means over two years (2014–2015).
CFU, colony-forming units.
Microbial populations were estimated from rhizosphere soil samples collected at harvest and expressed as colony-forming units (CFU) per gram of fresh soil.
CD, critical difference at P = 0.05; NS, not significant.
Figure 4
Total bacterial populations increased from initial stage to 45 DAE and varied at harvest. At harvest, mulched plots recorded significantly lower total bacterial counts compared to non-mulched plots.
Microbial inoculation significantly influenced rhizosphere populations. The consortium treatment recorded higher Rhizobium and PSB populations compared to individual inoculants. PSB populations were significantly higher under PSB and consortium treatments.
No significant interaction between mulching and microbial inoculation was observed for microbial populations. Microbial counts are expressed as CFU g-¹ soil basis.
3.5 Conceptual framework
The integrated effects of mulching and microbial inoculation on plant growth, nutrient uptake, and productivity under zero-fertilizer conditions are illustrated in Figure 5.
Figure 5
Polythene mulching influenced soil moisture and temperature conditions, resulting in improved plant growth and biomass accumulation. Microbial inoculation contributed to enhanced nodulation and nutrient availability. These combined effects were associated with improved productivity under zero-fertilizer conditions.
4 Discussion
4.1 Mulching governs biophysical yield formation
Polythene mulching significantly increased pod yield, pods per plant, kernel weight, and harvest index under zero-fertilizer conditions. These yield attributes likely reflect improved reproductive partitioning from soil moisture conservation and temperature moderation during pegging/pod stages (, ). Enhanced vegetative growth under mulch further indicates sustained assimilate production and translocation in heat-stressed Rabi–summer systems ().
Root elongation and biomass accumulated earlier under mulch than shoots, suggesting initial belowground resource capture before aboveground translation (). Microbial inoculation effects were less pronounced, with Rhizobium–PSB consortium showing numerically higher shoot/root growth (often non-significant), indicating physical factors dominated while co-inoculation supported rhizosphere functioning (). Root dry matter peaked at 75 DAE before declining due to reproductive partitioning and senescence ().
4.2 Consortium symbiosis: quality over quantity
Consortium inoculation enhanced effective nodulation and nodule biomass early/mid-season, particularly under mulched conditions (, ). PSB likely aided rhizobial infection via phosphorus solubilization when moisture was adequate, though interactions were non-significant for most traits (, ).
Higher effective nodules (vs. total count) in consortium treatments highlight symbiotic efficiency over quantity (). Rhizobial abundance rose in PSB plots from improved exudation/nutrient niches (). Numerical yield gains were insufficient for significance, reinforcing biophysical constraints under zero-fertilizer conditions ().
4.3 Mulching influences selective rhizosphere restructuring
Mulching reduced total bacterial abundance at harvest, likely from altered aeration/temperature/moisture under the film (, ). Consortium maintained higher rhizobial/PSB populations, suggesting selective favoring of adapted beneficials (, ).
This indicates mulching restructures rhizosphere communities functionally rather than uniformly suppressing them (). Native strains showed greater fitness in alluvial stress environments ().
4.4 Biophysical–microbial hierarchy under zero-fertilizer systems
Mulching establishes soil physical stability for growth, nodulation, and microbial optimization. Inoculation enhanced nutrient efficiency but was subordinate to physical regulation ().
Biological inputs alone cannot overcome moisture/heat limits; integrating adapted inoculants with mulch leverages native biology for low-input productivity. These findings collectively indicate that combining physical soil management with provenance-adapted microbial inoculants may represent a viable strategy for sustaining groundnut productivity under low-input alluvial agroecosystems.
5 Conclusion
The present study demonstrated that polythene mulching played the dominant role in improving groundnut performance under rainfed zero-fertilizer conditions by enhancing vegetative growth, nodulation, biomass accumulation, yield attributes, and final productivity. Improved soil moisture conservation and rhizosphere microenvironment under mulching likely supported better assimilate partitioning and reproductive efficiency during critical crop growth stages.
Microbial inoculation with native Rhizobium and phosphate-solubilizing bacteria (PSB), particularly under consortium application, improved effective nodulation and rhizosphere microbial persistence and produced numerically higher growth and yield responses. However, most inoculation and mulching × inoculation effects on yield parameters remained statistically non-significant, indicating that soil physical regulation exerted stronger influence on crop productivity than microbial inoculation alone under the prevailing environmental conditions.
The study further suggests that mulching selectively modulated rhizosphere microbial communities while supporting persistence of beneficial microbial populations under low-input conditions. Integration of provenance-adapted native bioinoculants with appropriate soil physical management therefore represents a promising strategy for sustaining groundnut productivity and rhizosphere functionality in fertilizer-limited alluvial agroecosystems.
Statements
Data availability statement
The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found in the article/supplementary material.
Author contributions
AS: Conceptualization, Data curation, Formal analysis, Investigation, Writing – original draft. SG: Conceptualization, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – review & editing.
Funding
The author(s) declared that financial support was not received for this work and/or its publication.
Conflict of interest
The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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The author(s) declared that generative AI was not used in the creation of this manuscript.
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Supplementary material
The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fsoil.2026.1819036/full#supplementary-material
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Summary
Keywords
groundnut (Arachis hypogaea L.), native strain, phosphate solubilizing bacteria (PSB), polythene mulching, rhizobium
Citation
Sengupta A and Gunri SK (2026) Interactive effects of polythene mulching and native bioinoculants on groundnut (Arachis hypogaea L.) productivity and rhizosphere microbial abundance under zero-fertilizer conditions. Front. Soil Sci. 6:1819036. doi: 10.3389/fsoil.2026.1819036
Received
27 February 2026
Revised
30 May 2026
Accepted
03 June 2026
Published
07 July 2026
Volume
6 - 2026
Edited by
Doongar R. Chaudhary, Central Salt & Marine Chemicals Research Institute (CSIR), India
Reviewed by
Jajati Mandal, University of Salford, United Kingdom
Kamal Krishna Pal, Directorate of Groundnut Research (ICAR-DGR), India
Updates
Copyright
© 2026 Sengupta and Gunri.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Amrita Sengupta, amritasenbckv@gmail.com
Disclaimer
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