Rice improvement in rain-fed agroecosystems requires a reliable assessment of drought tolerance in locally adapted germplasm. The present investigation was designed to evaluate the genetic diversity in drought-tolerant Ahu rice (Oryza sativa L.) cultivars of Assam, India, with SSR (simple sequence repeat) genotyping. Fifty drought-tolerant lines were screened out among 325 germplasm lines collected. A genetic variation study using 40 SSR markers revealed distinct genetic variation among the rice landraces, with two drought-tolerant lines, Nagina22 (N22) and APO, serving as references. The allelic count per locus throughout the twelve chromosomes varied from 2 to 6. The allelic mean per locus was 3.30, with an average PIC (Polymorphic Information Content) of 0.6938. The UPGMA algorithm-based dendrogram segregated the genotypes into six distinct clusters with a high degree of genetic variation. Five rice cultivars (Dumai, Tarabali, Payjihari4, Baismuthi, and Gerem dhan1) with robust drought tolerance tendency were further characterized by means of elevated production of ROS scavenging enzymes, cellular osmolytes. The present study will help the breeders in parental screening for the upcoming breeding programs of drought-tolerance.

This study examines the effects of climatic variability on bacterial and fungal populations, as well as enzymatic activities innutrient-rich, organic soils that support tea plants (Camellia sinensis L). Conducted from 2016 to 2019 across five district tea estates (TEs) in the Jorhat district of Assam, India, this research investigates the intricate relationships among these parameters. The findings indicate that bacterial and fungal communities exhibit optimal growth within a temperature range of 18 to 30 degrees C, establishing a critical threshold for their metabolic activity. A significant positive correlation was observed between the abundance of these microbial populations and the corresponding soil enzymatic activities, underscoring the essential role of these robust microbial communities in sustaining vital soil processes. Hierarchical cluster analysis identified two distinct groups of TEs that displayed consistent patterns of microbial behaviour across varying seasonal conditions. Furthermore, principal component analysis demonstrated that the first three principal components accounted for over 80% of the variability observed in the microbial and enzymatic data sets. This research contributes valuable insights into the dynamic interactions between seasonal fluctuations and soil health, highlighting the crucial contributions of bacterial and fungal populations, along with their enzymatic activities, to the complex ecosystem underlying tea cultivation.

The study investigated the influence of a National Highway (NH) traversing tea estates (TEs) on heavy metal (HM) contamination in the top soils of Upper Assam, India. The dispersion and accumulation of six HMs, viz. cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), and zinc (Zn), within tea-growing soils were assessed using diverse indices: contamination factor (CF), degree of contamination (DC), enrichment factor (EF), geo-accumulation index (Igeo), modified degree of contamination (MDC), Nemerow pollution index (PINemerow), pollution load index (PLI), potential ecological risk factor (Eri), and potential ecological risk index (RI). The order of HM prevalence was Fe > Mn > Zn > Ni > Cu > Cd. Elevated Cd levels near the NH prompted immediate attention, while Cd and Zn showed moderate pollution in CF, EF, and RI. The remaining metals posed minimal individual risk (Eri< 40), resulting in an overall contamination range of "nil to shallow," signifying slight contamination from the studied metals. From MDC values for investigated metals, it was found to be "zero to very low degree of contamination" at all locations except the vicinity of NH. Soil pollution, as determined by PLI, indicated unpolluted soils in both districts, yet PINemerow values indicated slight pollution. The statistical analysis revealed that there is a significant decrease in most of the indices of HM as the distance from NH increases. The application of multivariate statistical techniques namely Principal Component Analysis and Cluster Analysis showed the presence of three distinct homogenous groups of distances based on different indices. This investigation underscores NH-associated anthropogenic effects on TE soil quality due to HM deposition, warranting proactive mitigation measures.

Biochar is a solid carbonaceous pyrolyzed product prepared from various lignocellulosic biomass (agriculture and crop residues), sewage sludge, waste products obtained from different sources, litters, animal manures, etc., under limited oxygen conditions. In recent times, biochar applications in soil remediation, removal of hazardous organic and inorganic contaminants, wastewater treatment, electrode material, catalysis, etc., have drawn worldwide curiosity because of its unique properties. Instead of having unique properties, biochar application range is still limited due to its heterogeneous surface functionality, low porosity, and less adsorption capacity. The physicochemical properties of carbonaceous materials can be improved through various physical and chemical techniques, and biochar may be a better carbonaceous material due to its inexpensive and easy production process. Among physical modification techniques, steam activation is an environmentally and economically sustainable easy modification technique free from the use of any chemicals. With the advancement of nanotechnology, nanoscale engineering of biochar has captured care from scientific societies due to its nano-sized fabrication with excellent physical, chemical, and surface properties. Various mechanochemical techniques such as ball milling, microwave irradiation, and magnetic modification are vastly used for the nanoscale fabrication of biochar materials. Nanoscale engineering further increases the stability and efficiency of raw biochar material over physical modification techniques. This chapter includes steam activation used for physical activation of biochar as well as three selected mechanochemical techniques, viz. ball milling, microwave irradiation, and magnetic modification used for nanoscale modification of biochar along with their application in various fields. Biochar modification and its fabrication into nanoscale form is not only a novel approach but also provides a more advanced and efficient waste management technique.

Growing demand for foods for billions of hungry mouths is imitating high-yielding crop production which needs the application of an enormous amount of chemicals. Several human activities in recent years for societal development are also on the front foot. These agricultural activities coupled with non-systematic societal development create serious environmental pollution. Many technologies have been developed by impregnating biochar with hydrogel composites, as a sorbent to remove pollutants from water and soil. Biochar is a stable carbon-dominant material with porous structure, high surface area, developed pore structure, and low cost, which ensure its applicability as a porous absorbent. Agricultural waste biomass can be successfully converted into biochar by pyrolysis or thermochemical conversion technique. On the other hand, hydrogels are three-dimensional hydrophilic polymer molecules that can accommodate a significant fraction of fluids in their swelling form. Due to its unique bio-degradability, biocompatibility, and water retention properties, hydrogels are used as a carrier of biochar-based compounds to remediate environmental pollution. The formation of the biochar hydrogel composite systems could synergistically improve the inherent property of the sorbent system for the removal of contaminants. The most beneficial use of hydrogel-biochar nanocomposites is to remove the organic contaminant and toxic elements including chromium, arsenic, mercury, and lead in the aquatic environment via simultaneous adsorption and degradation. Most importantly, these composites contribute to waste management, climate change mitigation, and improving soil fertility. Water contaminants like phenol, dyes, and pharmaceutical hazardous compounds are effectively degraded by biochar-supported photocatalysts. In this chapter, an overview of current progress in the preparation of biochar-loaded hydrogel composites system is provided along with the potential application for removing the unwanted environmental threat. Herein, the chapter begins with a fundamental environmental contaminant and their effect on social ecosystem. We provide the basic information regarding practical information of biochar-based nanocomposites in the treatment of environmental contaminants.

A mammoth amount of tea pruning litter (TPL) is generated through the pruning of the tea plant and kept on the soil surface which makes the soil sick due to the accretion of allelochemicals from it. Therefore, appropriate management of TPL is very much crucial. This study was conducted to assess the role of tea pruning litter biochar (TPLBC) as a soil conditioner towards the growth and regulations of two popularly grown tea cultivars (TV23 and S.3A/3) in India. Altogether twenty-nine (29) parameters comprising functional groups, plant biomass, and physiological and biochemical properties have been reported in this study to understand the feasibility of TPLBC for tea cultivation. TPLBC amendment of 400 kg ha−1 was best suited for the used cultivars, leading to an increase in chlorophyll content, photosynthetic rate, stomatal conductance, transpiration rate, and water use efficiency by 25.68%, 49.61%, 84.00%, 126.93%, and 3.87% respectively. The maximum increase in plant total biomass, shoot biomass, and root biomass was attended at 110%, 31%, and 117%, respectively at 400 kg TPLBC ha−1 over control. The results also revealed an increase in the content of sugar, starch, phenol, total polyphenol, and amino acids with an increasing dose of TPLBC up to 400 kg ha−1. However, with 500 kg ha−1 TPLBC, plant biomass, and polyphenol content were decreased but oxidative stress was increased. Considering all the 29 variables it can be concluded that the soil amendment with 400 kg TPLBC ha−1 was most promising for both TV23 and S.3A/3 clones.

The effects of human activities are becoming clearer every year, with multiple reports of struggling and eroded ecosystems resulting in new threats of plant and animal extinctions throughout the world. It has been speculated that roadside tea-growing soils impact on metal dynamics from soil to tea plants and subsequently to tea infusion which may be threatened by increasingly unpredictable and dangerous surroundings. Furthermore, heavy metals released from vehicles on the national highway (NH) could be a source of metal contamination in roadside tea soils and tea plants. This study was articulated to realize the effect of NH on a buildup of selected metals (Cu, Cd, Fe, Mn, Ni, and Zn) in made tea along with repeated tea infusion. In general, metal concentration was found significantly higher in made tea prepared from the young shoots collected from the vicinity of NH. The results also showed that distance from the NH and infusion process significantly influenced to content of the analysed metal in tea infusions. The mean average daily intake (ADI) and hazard quotient (HQ) values of analysed tea samples were found in the orderMn˃Fe˃Zn˃Cu˃Ni˃Cd and Mn˃Cu˃Zn˃Fe˃Ni˃Cd, respectively. The HQ values of all analysed metals were found << 1, indicating that ingestion of tea infusion with analysed heavy metals should not cause a danger to human health. However, this study further demonstrates the consumption of tea infusion prepared from made tea around the vicinity of NH may contribute to a significantly higher quantity of metal intake in the human body. From the hierarchical cluster analysis, it has been observed that there are three homogenous groups of analysed heavy metals.

Phosphorus-loaded Ni–ZnO crosslinked carboxy methyl cellulose-based biodegradable nanocomposite hydrogel beads as multinutrient source of slow release fertilizer.

Harnessing the potential yields of evergreen perennial crops like tea (Camellia sinensis L.) essentially requires the application of optimum doses of nutrients based on the soil test reports. In the present study, the soil pH, organic carbon (OC), available potassium as K2O (AK), and available sulphur (AS) of 7300 soil samples from 115 tea estates spread over the Dooars ranging from 88°52’E to 89°86’E longitude and 26°45’N to 27°00’N latitude of West Bengal, India have been documented. About 54% of soil samples were found within the optimum range of soil pH (4.50-5.50) for tea cultivation. The overall range of OC was found from 0.28% to 6.00% of which, 94% of the analyzed samples were within the range of satisfactory to excellent level of OC i.e. (>0.80% to 6.00%). Around 36.3% of soil samples were found to have high AK (>100 mg kg-1) but 37.1% of soils were found to have high AS content (>40 mg kg-1). The nutrient index status of soil pH was low in Dam Dim, Chulsa, Nagrakata, Binnaguri, and Jainti sub-districts. Soils from five sub-districts had a high nutrient index (2.47 to 2.83) for soil organic carbon. However, it existed in the medium index (1.69 and 2.22) for Dalgaon and Kalchini sub-districts. Only Nagrakata sub-district soil samples were in the high nutrient index (2.65) for AK. All analyzed samples showed a medium nutrient index (1.97 to 2.27) for AS. The result indicated that soil pH was significantly negatively correlated with soil OC (-0.336) and AK (-0.174). However, the soil OC was significantly positive correlated with AK (0.258) and AS (0.100). It could be concluded that a balanced fertilizer application would be needed as a part of the soil improvement program through soil chemical tests for sustainable tea cultivation.

A field study was conducted from 0 to 360 days to investigate the effect of tea pruning litter biochar (TPLBC) on the accumulation of major micronutrients (copper: Cu, manganese: Mn, and zinc: Zn) in soil, their uptake by tea plant (clone: S.3 A/3) and level of contamination in soil due to TPLBC. To evaluate the level of contamination due to TPLBC, a soil pollution assessment was carried out using the geo-accumulation index (Igeo), enrichment factor (EF), contamination factor (CF), potential ecological risk factor (PERF), individual contamination factor (ICF), and risk assessment code (RAC). The total content of Cu, Mn, and Zn gradually increased with increasing doses of TPLBC at 0D, and then decreased with time. The fractionation of the three micronutrients in soil changed after the application of TPLBC. The contamination risk assessment of soil for Cu, Mn, and Zn based on the Igeo, EF, CF, PERF, ICF, and RAC suggested that the application of TPLBC does not have any adverse effect on soil. Except for Mn, the bioconcentration and translocation factors were less than one for Cu and Zn. Results from this study revealed that the application of 400 kg TPLBC ha-1 is significantly better than the other treatments for Cu, Mn, and Zn at a 5% level of significance.

Effect of tea pruning litter biochar (TPLBC) on arsenic (As), cadmium (Cd) and chromium (Cr) content in made tea and successive tea infusions were investigated in a greenhouse experiment with two tea cultivars (TV23 and S.3A/3). Made tea prepared from TV23 and S.3A/3 clone, a decrease in the concentration of As, Cd, and Cr by 36.73%, 16.22%, 13.96%, and 36.63%, 27.78%, 10.54%, respectively over control on the application of the highest dose of TPLBC (500 kg TPLBC ha−1). Irrespective of treatments, studied element concentrations were significantly higher (p ≤ 0.05) in the first infusion and lower in the third. Considering Ten g made tea consumption per person per day, the maximum average daily intakes of As, Cd and Cr in a higher dose of TPLBC were far below the tolerable weekly intake prescribed by the World Health Organization. As hazard quotient values of selected elements were ≪ 1, no significant adverse health consequences are expected for tea consumers.

Centella asiatica is a multipurpose medicinal plant which has been used traditionally in several systems of Asian medicine. The important role of C. asiatica in medicinal applications is attributed to its biologically active components of triterpene saponins. The isolation of good quality RNA is a pre-requisite for understanding the downstream molecular mechanisms leading to the synthesis of these secondary metabolites. The high cost of liquid nitrogen and commercially available kits is a major bottleneck for the developing countries. The present study describes a low cost, simple and reproducible RNA isolation method from leaves of C. asiatica without the use of liquid nitrogen or expensive RNA isolation kits. The protocol produced a yield of 2.7-3.1 mu g/mu l of total RNA and recorded an A(260)/A(280) ratio in the range of 1.8-2.0. The packaged cDNA library constructed from the isolated RNA showed an efficiency of 1.5 x 10(6) pfu/ml and the number of recombinant plaques comprised of 82%.

The changes in the climate due to global warming and ever dwindling arable land due to the population pressure are increasing strain on available resources for sustainable food production. Therefore, it is an urgent need to have proper idea about the effect of drought stress on crop plants for getting stable production through research intervention. Water deficit due to drought stress influences a wide range of plant processes, from whole plant growth and development to the molecular regulation of essential transcriptional pathways, and thus significantly impacts both physiology and metabolism. The studies about the changes in behavior of crop plants under drought condition have progressed at a rapid pace and extensive results of such analysis have been made public through various research articles, which can now be easily accessed through the World Wide Web. This review describes some aspects of drought induced effect of drought stress on different important traits of crop plants.

A good quality RNA is an important prerequisite for any downstream molecular analysis. However, isolation of quality RNA from tea is difficult due to presence of high amount of phenols and polysaccharides. We describe here an efficient protocol for total RNA isolation without liquid nitrogen from apical buds and tender leaves of tea. This protocol yielded RNA 1248+/-23 mu g/g of fresh leaf tissue with high purity. The RNA was also found to be suitable for mRNA purification, cDNA synthesis and cloning through RT-PCR (reverse transcription-polymerase chain reaction) and cDNA library construction.

Tea is the most popular non-alcoholic and healthy beverage across the world. The understanding of the genetic organization and molecular biology of tea plant, which is very poorly understood at present, is required for quantum increase in productivity and efficient use of germplasm for either cultivation or breeding program. Single-pass sequencing of randomly selected cDNA clones is the most widely accepted technique for gene identification and cloning. In the present study, a good quality cDNA library was constructed and preliminary analysis of ESTs was carried out. The titers of unamplified and amplified libraries were 1.4 × 106 pfu/ml and 5.27 × 108 pfu/ml respectively. A total of 210 cDNA clones from the constructed cDNA library were sequenced and analyzed. A total of 84 high quality Expressed Sequence Tags (ESTs) were generated, among which 71 ESTs had significant homology with sequences in NCBI non-redundant protein database by BLAST X analysis. About 80% ESTs had poly (A) tail at 3′ end indicating that the cDNAs were full length. The database-matched ESTs were classified into putative cellular roles, viz. energy-related category (corresponding to 20% of total BLAST X matched ESTs), Transcription (14.2%), protein synthesis (14.2%) cell growth and division (8.6%), cell structure (5.7%), signal transduction (5.7%), transporters (2.9%), disease and defenses (2.9%), secondary metabolism (2.9%) and gene regulation (2.9%). This study provides an overview of the mRNA expression profile and first hand information of gene sequence expressed in tender leaves and apical buds of tea plant.