Silicon (Si) deficiency limits plant growth, physiological efficiency, and yield in high-value crops such as Coriandrum sativum L. A field experiment was conducted on Si-deficient soil at TNAU Coconut Farm, Coimbatore, India, using coriander variety CO (CR) 4. Seven treatments in a randomized block design with three replications evaluated calcium silicate (CaSiO3), and rice husk ash (RHA) at 225, and 275 kg Si ha− 1, alone, and combined with Bacillus altitudinis SSB4, across growth, physiological, biochemical, antioxidant, and yield parameters. Si + SSB4 integration significantly improved plant height (up to 60.9

Phosphorus (P) is an essential macronutrient involved in energy metabolism, regulation of physiological processes, and biomass production in plants. P deficiency is a major constraint to plant growth, and its direct effects are often obscured in soil-based studies due to phosphorus fixation and microbial interactions. The Present study evaluated the varying inorganic phosphate (Pi) concentrations (0.001, 0.025, and 0.25 mM Pi) on morphology, dry matter allocation, gas exchange, PS II efficiency, and photosynthetic pigment composition on 21-day-old muskmelon (Cucumis melo L.) seedlings grown under hydroponic conditions. Adequate Pi (0.25 mM Pi) supply significantly enhanced the shoot growth, total dry weight, photosynthetic rate, stomatal conductance, and transpiration. These responses were closely associated with higher PS II efficiency, indicated by increased Fv/Fm and Fv/Fo ratios and photosynthetic pigments chlorophyll a, chlorophyll b, and carotenoid. Reduced Pi (0.001 mM Pi) limited the growth, gas exchange, PS II efficiency, and photosynthetic pigments, and while promoting root growth and increasing root-to-shoot ratio. The coordinated modulation of growth, physiological, and photochemical responses of muskmelon seedlings under controlled Pi supply demonstrates that phosphorus availability directly regulates photosynthetic functionality and biomass allocation.

Exopolysaccharides (EPS) are biological polymers secreted by microorganisms and are gaining attention due to their widespread use; however, their yield relies on the culture conditions. This study reports the EPS-producing bacterium Bacillus rugosus L1C7T for EPS production and describes the EPS, as well as its potential applications. Response surface methodology (RSM) was employed to optimize the growth medium and enhance EPS production to achieve this goal. The highest concentration of EPS (1.35 g l− 1) was obtained in a culture medium that contained 11.25 g of NaCl, 6.25 g of K2HPO4, and a C/N ratio of 0.5. The EPS of B. rugosus L1C7T was analyzed using FT-IR, and the results revealed the presence of the following functional groups: O-H, C = O, C-C, C = C = C, N = C = S, C-O-C, N = C = O, and N = O. The 1H NMR spectroscopy of the EPS revealed the presence of pyranose, 6-deoxy and acetyl sugars spectra. Additionally, this EPS demonstrated suitable radical scavenging capabilities, outstanding water solubility, water absorption, and oil absorption capacities of 125

Alterations in land patterns in Kolli Hills(KH) of the Eastern Ghats, Tamil Nadu, transitioning from native ecosystems to various land uses, have notably diminished soil carbon concentrations. To measure this reduction, the Carbon Management Index (CMI) was evaluated across key land-use categories, including Agricultural System (AS), Horticultural System (HS), Plantation System (PS), Thorn Forest (TF), Deciduous Forest (DF), and Evergreen Forest (EF). The analysis focused on Total Organic Carbon (TOC), Total Carbon (TC), Total Inorganic Carbon (TIC), and carbon pools with varying degrees of lability, including less labile carbon (LLC), labile carbon (LC), very labile carbon (VLC), and non-labile carbon (NLC). The findings indicated that EF's carbon pools were markedly higher (p < 0.05) than AS and HS. The contribution of LC, VLC, LLC, and NLC to TOC was highest in EF and DF, while it was lowest in AS and HS. The TOC at 15 cm depth was highest in the surface soils of EF (106.17 g kg-1), with a gradual decline in concentration with increasing depth. This highlights carbon pool degradation from land-use change, quantified by the CMI. When EF was used as the reference ecosystem, the CMI was higher in DF (51.93) and TF (45.69) at a 30 cm depth, while AS (10.75) and HS (12.46) showed a much lower CMI. These findings highlight the need to implement effective carbon management strategies in KH to restore soil vitality and safeguard biodiversity.

Soil quality indices (SQIs) assess an ecosystem’s susceptibility to land-use change (LUC), highlighting the impacts on soil parameters. This study developed an SQI for six ecosystems in the Kolli Hills (KH), Eastern Ghats (EG), India: evergreen forest (EF), deciduous forest (DF), thorn forest (TF), agricultural system (AS), horticulture system (HS), and plantation system (PS). Soil samples were collected at two depths, surface (15 cm) and subsurface (30 cm), from 240 sites (40 samples per depth per ecosystem) and analyzed. LUC altered the soil physical and chemical properties. AS and HS had higher sand content (54.63

The notable increase in chicken waste resulting from the rapid expansion of the chicken industry represents a major concern and danger to public health and the environment. Therefore, this varied waste stream in the chicken industry, including bedding materials, dung, feathers, and mortalities, requires efficient management techniques. Improper chicken waste disposal can lead to nutrient leakage and water and soil contamination, which can cause eutrophication and aid in spreading harmful bacteria such as Escherichia coli and Salmonella. Moreover, untreated waste exacerbates climate change by increasing greenhouse gas emissions. Thus, in response to these challenges, this review analyses many treatment techniques that might convert this complicated waste stream into a useful resource to support environmental sustainability in the chicken industry and enhance soil health. Furthermore, this study evaluates gasification, pyrolysis, anaerobic digestion, and composting as viable methods to reduce pollution from chicken waste while producing useful byproducts. Anaerobic digestion uses bacteria to produce biogas, a sustainable energy source; pyrolysis produces biochar and bio-oil; composting converts waste into fertilizer; gasification produces syngas for fertilizer production. However, choosing the most efficient treatment approach necessitates thoroughly assessing waste properties, intended end products, and economic factors. This review aims to expand the understanding of these treatment procedures and their related advantages to assist in developing sustainable and effective strategies for dealing with chicken waste. These strategies, which prioritize value development, environmental preservation, and public health, have the potential to pave the way for a more responsible and sustainable future for the chicken industry.

Silicon is an essential mineral that plays a crucial role in increasing plant growth, improving crop yields, and imparting resilience against environmental stresses. This study explored the silicate solubilization potential of Achromobacter sp. L1C9T2, Bacillus altitudinis L3C3T2, Bacillus safensis L5C13T, Bacillus altitudinis SSB4, and Priestia aryabhattai KSBN2K7 using three silicate minerals, magnesium trisilicate (MGT), quartz (QT), and bentonite (BT). Both qualitative and quantitative assessments revealed that the maximum silicate solubilization was exhibited by Bacillus altitudinis SSB4 (87.71

Muskmelon (Cucumis melo L.), a hydrating fruit rich in antioxidants, vitamins, and minerals, is widely grown in tropical and subtropical regions where phosphorus (P) deficiency is common. P availability influences sugar and acid contents in melons because of its role in sugar acid phosphatase enzymes. Increasing phosphorus use efficiency through the use of biostimulants, particularly phosphorus-solubilizing bacteria, represents a promising approach for sustainable muskmelon production. These biostimulants solubilize inorganic P by releasing phosphatase enzymes and organic acids. This study examined the effects of three P levels (100%, 50%, and 0% P₂O₅) and biostimulants (control, GEA 1499- a formulation containing plant base biostimulant and the microbial species Bacillus pumilus and Bacillus megaterium at 2.5 kg ha-1, and GEA 1499 at 5 kg ha-1) on muskmelon morphology, physiology, biochemistry, and yield. The combination of 100% P₂O₅ with GEA 1499 at 2.5 kg ha-1 significantly improved the leaf count, vine length, photosynthesis, stomatal conductance, transpiration, chlorophyll index, marketable yield, and total soluble solids while reducing the undesirable traits rind thickness and seed cavity dimensions, indicating improvement in fruit quality. Phosphorus enhances gas exchange via ATP and the Calvin cycle, whereas biostimulants containing microbes and plant extracts improve nutrient availability, promoting better muskmelon growth, yield, and fruit quality. A combination of plant extracts provides phytohormones that complement the microbial action and improve the overall efficiency of the biostimulant.

Thermo-sensitive genic male sterile (TGMS) lines in rice are crucial for hybrid breeding, enhancing genetic diversity by eliminating the need for manual emasculation and restorer genes. These lines induce sterility at high temperatures and restore fertility at low temperatures, in contrast to cytoplasmic male sterility (CMS) systems that require specific restorative genes. This temperature-sensitive mechanism allows for greater flexibility in pairing parent lines, increasing genetic diversity and enabling recombination of beneficial traits in hybrids. A randomized block design (RBD) with three replications was employed for the evaluation of these TGMS rice lines. This study investigates the molecular diversity and genetic variability among TGMS rice lines. Traits such as single plant yield, grains per panicle, glume angle, and pollen fertility showed significant phenotypic and genotypic variation, indicated by high coefficients of variation (PCV and GCV), heritability estimates, and genetic advance as a percentage of mean (GAM). These results highlight substantial genetic variation and selection potential. Euclidean distance matrix analysis of morphological data revealed notable genetic differences. TNAU 137S 1 and TNAU 137S 2 were the most genetically similar, while TNAU 112S and TNAU 114S showed the greatest divergence. Principal component analysis (PCA) revealed distinct genetic profiles among lines such as TNAU 136S, TNAU 113S, TNAU 142S, and TNAU 126S, important for hybrid development. Molecular diversity analysis using simple sequence repeat (SSR) markers identified 90 alleles and eight genetic clusters. Bayesian analysis further confirmed two major subpopulations with significant genetic divergence. These findings support the selective use of parent lines for hybrid rice breeding.

Magnesium (Mg) an essential plant nutrient is widespread deficient in the acidic soils of Nilgiris of Tamil nadu, India. The vegetable yield and quality is especially affected due to deficiency of nutrients like Mg. This study investigates soil characteristics and bacterial diversity in the Nilgiris district of Tamil Nadu, India, with respect to Mg deficiency. The soil samples were collected from different vegetable growing regions of the Nilgiris to assess soil physiocochemical parameters, soil enzymes and soil Mg status. 16S rRNA gene-based metagenomic analysis used to investigate the functional potential and structural diversity of the bacterial communities in high Mg and low Mg deficiency soil. Results indicated mildly acidic soils with a sandy loam texture and high organic carbon content. While nitrogen (N), phosphorus (P), and potassium (K) levels were adequate, Mg deficiency was consistent. Soil enzymes such as dehydrogenase, acid phosphatase, urease and aryl sulfatase, varied across the soil samples. Additionally, 16S rRNA gene-based metagenomics analysis revealed the bacterial diversity and functional pathways in soils with high and low Mg deficiency. Low Mg levels were associated with increased bacterial richness, dominated by Proteobacteria, Gemmatimonadetes, Actinobacteria, Bacteroidetes, and Acidobacteria. Functional pathways related to carbon metabolism, amino acid biosynthesis, and various metabolic processes were more abundant in low Mg deficient soils. This research highlights the significant influence of Mg levels on bacterial diversity and functional potentials in acidic soils, providing insights into soil management strategies in Mg-deficient regions.

Salinity stress poses a critical threat to global crop productivity, driven by factors such as saline irrigation, low precipitation, native rock weathering, high surface evaporation, and excessive fertilizer application. This abiotic stress induces oxidative damage, osmotic imbalance, and ionic toxicity, severely affecting plant growth and leading to crop failure. Silicon (Si) has emerged as a versatile element capable of mitigating various biotic and abiotic stresses, including salinity. This review offers a comprehensive analysis of Si's multifaceted role in alleviating salinity stress, elucidating its molecular, physiological, and biochemical mechanisms in plants. It explores Si uptake, transport, and accumulation in plant tissues, emphasizing its contributions to maintaining ionic balance, enhancing water uptake, and reinforcing cell structural integrity under saline conditions. Additionally, this review addresses Si transformations in saline soils and the factors influencing its bioavailability. A significant focus is placed on silicon-solubilizing microorganisms (SSMs), which enhance Si bioavailability through mechanisms such as organic acid production, ligand exchange, mineral dissolution, and biofilm formation. By improving nutrient cycling and mitigating salinity-induced stress, SSMs offer a sustainable alternative to synthetic silicon fertilizers, promoting resilient crop production in salt-affected soils.

Accurate and quantitative assessment of Land Use and Land Cover (LULC) changes is crucial for understanding the spatial dynamics and environmental impacts within specific regions. In hilly terrains like the Nilgiris district in Tamil Nadu, India, these assessments are particularly challenging due to the complex topography and when classified using sparse ground truth labels. With numerous data mining algorithms being validated for several earth observation applications, demands are also increasing in selecting the best classifier algorithm for LULC mapping. Popularly implemented pixel-based data mining classifiers such as Random Forest (RF), Support Vector Machine (SVM), C5.0 Decision trees (C50), Naive Bayes (NB), Multinomial Logistic Regression (MLR), AdaBoost, Bagged CART, Nearest Shrunken Centroids (NSC), Genetic Algorithm based CART (Evetree), Neural Networks with PCA (NNPCA), k-Nearest Neighbours (k-NN), Multi-Layer Perceptron (MLP), and 1 Dimensional – Convoluted Neural Networks (1DCNN) were studied by integrating different auxiliary variables with sparse ground truth labels (391 Nos.). The accuracy of the predictions was then validated using Overall Accuracy (OA), Kappa, and disagreement measures based on the validation datasets. The most influential auxiliary variables contributing to the classification determined through PFI (Permutation Feature Importance) analysis, resulted with Digital Elevation Model (DEM) being the most influential auxiliary variable, among others. From the validation measures and the visual assessment facilitated for each algorithm, the effective performance in classification was depicted by Support Vector Machine - Linear Kernel (SVM - L) and followed by Random Forest (RF) algorithms with OA of 88

High soil pH and excess CaCO3 are major contributors to calcareous soil limitations on crops’ access to essential nutrients, especially phosphorus (P) and micronutrients, which in turn impact pulses yields and growth. The purpose of this study was to determine the effect of bio sulfur granules (BSG) on the growth of black gram and the availability of nutrients in calcareous vertisols deficient in sulfur. BSG was developed by using sulfur-oxidizing bacteria (SOB) and elemental sulfur (ES) through an incubation study. Developed BSG was tested in a pot and field conditions to evaluate their effectiveness on black gram growth and yield. In the incubation study, soil treated with Methylobacterium thiocyanatum VRI7-A4 and ES (40 kg S/ha) significantly decreased pH and increased available S (SO42−) in calcareous soils. After 40 days of incubation, the solubility of P, Fe, and Zn was greatly increased by the addition of ES @ 40 kg S/ ha in combination with M. thiocyanatum VRI7-A4 or Pandoraea thiooxydans ATSB16. Black gram in S-deficient calcareous soil was improved by the application of BSG (ES @ 40 kg S/ ha with M. thiocyanatum VRI7-A7) in terms of root and shoot lengths, nodule number, plant biomass, pod yield, and biological yield as compared to control. The same treatment greatly increased plant nutrient intake as well as the concentrations of P, Fe, and Zn in the soil. The results showed that the addition of BSG granules (ES @ 40 kg S/ha + M. thiocyanatum VRI7-A4) to calcareous vertisol deficient in S enhanced the nutrient solubility through S oxidation. The developed bio sulfur granules may be added to the fertilizer schedule of the pulses growers to get improved crop growth and yield of black gram in calcareous soil.

Background: Cotton, maize and pulses are widely grown crops in the western zone of Tamil Nadu, resulting in a significant accumulation of crop residues throughout the year. The persistence of these crop residues after harvest can cause problems for farmers and the soil system. Therefore, the goal of the current study is to investigate the carbon mineralization process in these residues to enrich the soil’s nutrient content, turning waste into a valuable resource. Methods: The incubation experiment comprised 13 treatments, each with three replicates. These included a control, surface residue addition, buried residue addition and various combinations of soil, residue, microbial consortia, urea and jaggery, both on the soil surface (S) and incorporated into the soil (I). Result: The incorporation of crop residues into the soil, along with the addition of 1% microbial consortia, 2.0% jaggery and 1% urea, significantly enhanced carbon mineralization. Among the three crop residues, cowpea exhibited the highest performance, followed by cotton and maize, with values of 692, 564 and 522 µg C g-1 soil, respectively. This trend was further supported by the Michaelis-Menten model (V = 951.72 * x/22.13 + x), with a high goodness-of-fit represented by an R2 value of 0.95 for cowpea. The maximum Vmax (951.72 µmol/min) further substantiates the efficient carbon mineralization achieved by utilizing allocated resources in cowpea-incorporated crop residues (CWFI).

Calcareous soils are soils containing amounts of calcium carbonate that distinctly affect the soil properties related to plant growth, whether physical, such as soil–water relations and soil crusting, or chemical, such as the availability of plant nutrients. The primary crop productivity constraints in calcareous soils include phosphorus and trace element (e.g., iron, zinc, and copper) deficiency, surface crust formation, and an impermeable subsurface compact layer. Soil productivity constraints in calcareous soils can be overcome by adequately choosing and placing fertilizers and adding organic matter. Applying acid-forming fertilizers such as ammonium sulfate and urea fertilizers, sulfur compounds, organic manures, and green manures is considered an effective measure to reduce the pH of the soil to a neutral pH value. Elemental sulfur is one amendment that can be used to lower the pH of a calcareous soil. Even sulfur will take some time to be effective. Sulfur-oxidizing bacteria (SOBs) can be essential in reclamation soils with alkaline, sodic, and calcareous properties. Through biochemical sulfur oxidation, SOBs can convert reduced inorganic sulfur compounds into sulfuric acid, reducing soil pH and dissolving calcium carbonate in calcareous soils. This chapter extensively discusses the characteristics of calcareous soils, nutrient limitations, and the use of colorless SOBs to enhance nutrient availability and plant growth in calcareous soils.

The study aimed to investigate the impact of zinc (Zn) nutrition on enzymatic activity in soil and plant systems of zinc-deficient soils. Additionally, it aimed to understand the impact of solubilizer (such as Zinc Solubilizing Bacteria) and mobilizer (like AM Fungi) on enzyme activity and zinc nutrition in plants across calcareous and non-calcareous soil environments. A pot experiment was carried out with two different soils with three Zn sources (ZnSO4, ZnO and Zn-EDTA), organic manure (FYM) and microbial inoculants - Zinc Solubilizing Bacteria (ZSB) and Arbuscular Mycorrhizal Fungi (AM F). The DTPA-Zn and plant Zn content increased with applied sources of Zn. The microbial inoculants and FYM enhanced the use efficiency of all sources of Zn compared to unapplied treatments. Regarding soil enzyme activity, FYM and AM fungi played a major role which in turn altered the dehydrogenase (SDHA) and alkaline phosphatase (AlP) activities in both soils. The Zn sources and ZSB addition enhanced the plant enzyme activity. Calcareous soil recorded higher CA, SOD and alkaline phosphatase activities compared to non-calcareous soil the latter registered higher dehydrogenase activity and fruit Zn content.

Changes in land use have an impact on ecosystem services by affecting soil quality. Thus, soil quality assessment using the soil quality index (SQI) can help better understand the LUC (land use change) impact on soil health. This study was established to explore the soil quality of the Nilgiri Hill Region (NHR) in the Western Ghats global biodiversity hotspot (India’s first biosphere reserve) under six major ecosystems cropland (CL), deciduous forest (DF), evergreen forest (EF), forest plantation (FP), scrubland (SL) and tea plantation (TP). The minimum data sets (MDS) were selected using PCA (Principal component analysis) and EO (Experts’ opinion). LUC from the natural ecosystem has significantly decreased soil quality. The selected indicators under PCA (water-soluble carbohydrates, microbial biomass carbon, dehydrogenase, available K, available N and carbon stock), and EO ( aggregate stability, pH, CEC, available N, available Zn, passive pools, CO2, dehydrogenase, and aggregate size organic carbon (2 mm)) spotlights the wide variation between the natural and the altered ecosystems. Furthermore, the selected indicators were positively correlated with total organic carbon (TOC). This research cautions that the LUC will have a substantial effect on soil quality, a crucial factor for achieving a future that is environmentally sustainable. Our research indicates the need for an immediate implementation of management strategies to improve the soil quality in degraded ecosystems (CL and TP) of NHR.

Background: Recycling of crop residues has gained attention over the past few decades due to its influence in sustaining the soil fertility and crop production. In this context, it is of crucial to study the effect of crop residue type, placement and tillage on decomposition and nutrient release in tropical agriculture. Methods: We conducted a litter bag decomposition experiment to evaluate the rate of mass loss, carbon (C), nitrogen (N) and phosphorus (P) mineralization from crops residues. We used residues of cotton, maize and cowpea. Result: Result indicated that cowpea and cotton residues decomposed more rapidly than maize residues, with mass loss of 50-65% occurring within 40 days of placement. Plough depth placement resulted in faster decomposition than deep placement, with 78% of initial mass and nutrient contents lost at the end of 120 days. Over 50% of nutrient mineralization occurred in the first 30 days of decomposition from cowpea residues. At the end of the 120th day, 0.28%, 0.19% and 0.30% of total nitrogen content remained out of 2.15%, 0.86% and 1.22% of the initial total nitrogen in cowpea, maize and cotton residues, respectively. More than 48% of residue breakdown and nutrient mineralization occurred in the first 40 days of decomposition, suggesting that farmers can boost crop growth by choosing crop residues with a low and medium C:N ratio and placing residues at a plough depth (0-15 cm) using reduced tillage practices.

Bioavailability of zinc was impacted by soil properties, externally applied sources, time, and various fractions of zinc. An experiment was conducted to investigate the bioavailable and other zinc fractions in calcareous soil and the efficiency of organic and inorganic sources on bioavailability with the presence and absence of zinc solubilizing bacteria (ZSB). The sequential extraction procedure followed at every interval of the incubation period for all forms of zinc was studied. Externally added inorganic sources significantly affected all fractions of zinc compared to untreated soils. Among them, ZnSO4 influences all forms of zinc, mainly Ws+Ex (water soluble+exchangeable) and carbonate-bound zinc, whereas Zn-EDTA maintains a high status of bioavailable zinc throughout the experimental period. On the 60th day of incubation, Zn-EDTA and ZnSO4 applied to soil maintained bioavailable zinc content of 3.71 and 2.94 times higher than that of control. Irrespective of sources, the available zinc of Zn fertilizers applied to soils was reduced with an increase in incubation days. Organic and microbial addition effects solely or combined increase the soil zinc content significantly in both fertilized and unfertilized soils. Among two different organic sources, the zinc solubility performance of farmyard manure was higher than that of vermicompost. In untreated soil, residual and carbonate-bound fractions contribute a major portion towards total zinc based on quantity. The bioavailable fraction mainly the Ws+Ex and organically bound fractions were markedly influenced in all treatments.

Land use change (LUC), alters the multifarious biodiversity hotspots directly and indirectly through the loss of soil quality. A comparative study on soil carbon status and soil microbiome in undisturbed natural forest eco-systems with that of other land uses which gradually altered over time can serve as a suitable indicator for understanding LUC impact on carbon cycles. With this aim, the current investigation was initiated to infer the cyclic effects of LUC on the soil carbon status under six major ecosystems viz., cropland (CL), deciduous forest (DF), evergreen forest (EF), forest plantation (FP), scrubland (SL) and tea plantation (TP) of the Nilgiri Hill Region (NHR) (India's first biosphere reserve). The total organic carbon (TOC) and carbon stocks were highest in evergreen forest (10.25 %, 322.06 t ha-1) and they decreased with increasing depth of the soil profile across the pools of varying carbon lability. The proportion of active carbon pools (AP) in total carbon was higher in crop land and tea plantation (57.47 %, 58.38 %), however, in the case of evergreen forest, deciduous forest, forest plantation and scrub land the passive carbon pools (PP) (54.99 %, 61.28 %, 59.43 % and 60.70 %) was higher. We discovered LUC has altered the proportion of soil carbon pools, and the efficiency of soil microbiome and has resulted in higher carbon dioxide (CO2) emissions in tea plantation (71.87 t ha-1) and crop land (82.39 t ha-1). However, the native ecosystems (evergreen forest and deciduous forest) with higher recalcitrant carbon pools (46.96 g kg-1 and 34.89 g kg-1) prevent such carbon degradation and thereby hinder the soil carbon emissions as recorded in evergreen forest (48.43 t ha-1) and deciduous forest (56.47 t ha-1). Conclusively, our study demonstrates that LUC has substantially influenced the carbon cycle by altering the carbon stocks and CO2 emissions in relation to soil microbes. Henceforth, in order to maintain carbon footprints and attain carbon net neutrality under the current climate change scenario, suitable carbon management measures must be implemented in carbon-degraded ecosystems (crop land and tea plantation) of NHR.