The Tocklai Experimental Station is a research facility for the development of tea..
Climate change is accelerated by increasing levels of greenhouse gases (GHGs) as a result of human activity, particularly the release of carbon dioxide (CO2). Soil carbon (C) sequestration, or the transfer of atmospheric CO2 to soil organic matter (SOM) with long-term stabilization within the soil, is an important process of C removal from the atmosphere. For the accounting of soil C and offset markets in most countries including Australia, the standard soil sampling depth is 0–30 cm, although deeper sampling is recommended for more accurate C stock assessments and to capture long-term sequestration potential. While 30 cm soil depth accounts for most short-term management impacts on C storage, a significant portion of soil C is stored below this depth (i.e., deep soil C), and sampling at greater depths can provide a more complete account of total C stocks and potential sequestration benefits. This paper aims to provide a comprehensive review, including a bibliometric analysis and a critical discussion of the link between deep soil C storage and sequestration potential in relation to climate change mitigation and soil health. Deep soil layers contain over 850 Pg C worldwide, which is approximately 50
Incessant mica mining and improper disposal of mine waste have resulted in widespread arsenic (As) contamination in agricultural soils. Microbially augmented vermicomposting recently emerged as a promising approach to transform toxic mine waste into a nutrient-rich organic amendment, however, its field-scale adoption and validation for arsenic immobilization remain limited. This study evaluated the performance of vermicomposts prepared using mica mine tailings (MMT). Soil physicochemical, microbial, macronutrient, and arsenic content were measured, alongside crop yield and biochemical parameters. Treatment T5 [bacteria-supplemented MMT (1:1) vermicompost (50
Black tea quality is fundamentally determined by its biochemical composition, providing essential baseline data for producers, traders, and consumers. This study comprehensively evaluates key biochemical quality components of 32 black tea samples from Upper Assam and North Bank regions of Assam, India, produced by both orthodox and CTC methods, using standardized International Organization for Standardization (ISO) analytical protocols for total polyphenols (TP), theaflavins, catechins, water extract (WE), caffeine, thearubigins (TR), theanine, crude fibre (CF), and ash characteristics. The results reveal substantial variation in TP (83.54-184.52 mg g-1, avg. 134.07 mg g-1), theaflavins (4.88-15.54 mg g-1, avg. 8.61 mg g-1), caffeine (15.51-39.24 mg g-1, avg. 30.09 mg g-1), and theanine (2.47-8.16 mg g-1, avg. 5.53 mg g-1), demonstrating substantial biochemical variation reflecting differences in cultivation practices, leaf maturity, processing conditions and agroclimatic conditions. The orthodox and CTC methods yielded comparable WE (avg. 404.34 vs. avg. 407.91 mg g-1) and theanine levels (avg. 5.65 vs. avg. 5.35 mg g-1) indicating that both processing types successfully retain key quality components. All analyzed biochemical attributes with established minimum or maximum limits set by the ISO and Food Safety and Standards Authority of India (FSSAI) demonstrated compliance with national and international quality standards. These findings establish contemporary benchmarks for key quality indicators in Assam black teas and confirm the consistency of quality across diverse processing methodologies and cultivation practices.
Zinc oxide nanoparticles (ZnO-NPs) are emerging as effective micronutrient carriers with additional antifungal properties. However, their application in perennial plantation crops such as tea (Camellia sinensis) remains unexplored. Fusarium solani, a destructive soil-borne pathogen, poses a significant challenge in tea nurseries and plantations. Greenhouse pot trials were conducted using ZnO-NPs at 3, 6, and 9 mg kg−1, with ZnSO4·7H2O serving as the conventional zinc control. Disease severity, rhizosphere colony-forming units (CFU) populations, soil zinc availability, foliar uptake, microbial biomass, and chlorophyll traits were assessed over 30 days. ZnO-NPs reduced disease severity by 18–55 % and suppressed rhizosphere F. solani CFU counts by up to 69 %, significantly outperforming ZnSO4·7H2O. They increased DTPA-extractable soil Zn (to 0.84 mg kg−1) and improved foliar Zn uptake. In comparison, the 6 mg kg−1 dose enhanced chlorophyll a and total chlorophyll, while maintaining near-baseline microbial biomass. Although the 9 mg kg−1 dose yielded higher pathogen suppression, it reduced microbial biomass carbon by 19 %. Microscopy confirmed collapsed hyphae and deformed conidia, consistent with oxidative stress and cell wall disruption. This study provides the first greenhouse-based evidence that ZnO-NPs can function as dual-action soil amendments in tea, improving both nutrient status and resistance to F. solani. The intermediate rate (6 mg kg−1) delivered the best balance between plant benefits and microbial stability, highlighting the agronomic promise of nano-enabled inputs. Further multi-season field studies are needed to verify their effectiveness and environmental safety.
Tea dieback disease caused by Fusarium solani (Mart.) Sacc. is an emerging constraint to tea (Camellia sinensis L.) production in several tea-growing regions, including Assam, India. In this region, the disease poses a growing threat to pluckable tea yield, with reported losses of up to 20% in harvestable shoots under severe infection, underscoring the need for more effective and judicious disease management strategies. In the present study, zinc oxide nanoparticles (ZnO-NPs) synthesized via a sol–gel route were evaluated for antifungal efficacy against F. solani under laboratory and field conditions, supported by comprehensive physicochemical characterization. X-ray diffraction confirmed the formation of phase-pure hexagonal wurtzite ZnO with an average crystallite size of 12.04 ± 2.45 nm. F. solani was isolated from infected tea plants in Assam, India, and identified by ITS region sequencing (GenBank accession PV171106.1) and TEF1-α sequencing (GenBank accession PX903872). In vitro assays demonstrated concentration-dependent inhibition of mycelial growth and spore germination, with ZnO-NPs showing stronger antifungal activity than zinc sulfate (ZnSO4), which was used as a soluble ionic zinc control. The EC50 for mycelial growth inhibition was 465.6 μg mL−1 for ZnO-NPs, compared with 992.4 μg mL−1 for ZnSO4, while spore germination was inhibited by up to 85.50 ± 2.22% at 1200 μg mL−1. Scanning electron microscopy further revealed severe hyphal deformation and surface disruption following ZnO-NP exposure.Field evaluation demonstrated that short-term foliar application of ZnO-NPs significantly reduced disease severity, achieving up to 47.34% suppression by Day 30. Treated plants also exhibited lower disease intensity together with increased leaf chlorophyll content and enhanced foliar zinc accumulation. These findings confirm that ZnO-NPs possess measurable antifungal activity against F. solani under field conditions and may contribute to short-term suppression of tea dieback while simultaneously improving plant physiological status. However, because the field assessment was limited to a 30-day observation period, the results should be interpreted as evidence of short-term suppression rather than sustained long-term efficacy.
