Varatharajan Krishnakumar

• PhD
• Head of Faculty at Periyar University

Perennial plantation crops, such as coconut trees require the systematic addition of nutrients for sustained growth and productivity. This study aimed to understand plant and soil nutrient dynamics, root health and soil biological properties upon addition of specific nutrients in tropical land use systems. Field experiments in randomised block desi...

The book on " Palms" provides a comprehensive coverage of palms giving details such as origin and distribution, diversity, morphology, medicinal properties and value added products of commercially important palms ( coconut, areca-nut, palmyrah, date palm and oil palm ) as well as various ornamental palms for landscape management and much more. The...

It is crucial to achieve economic and ecological sustainability in the production of plantation crops in view of their importance to support the livelihood of millions of farmers and agro-industrial entrepreneurs by supplying food, fiber, and industrial raw materials. Plantations are developed by clearing forests, and these perennial crops are conf...

Tea, an important cash crop of many developing countries, has considerable socio-economic importance for rural development and poverty alleviation. More than three billion people in 160 countries and regions drink tea. Major tea producing countries of the world are China, India, Kenya, and Sri Lanka and they cultivate tea under different geo-physic...

Plantation crops are perennials, cultivated in a contiguous area in agroecosystems mostly confined to tropical belt, and comprise estate crops which include tea, coffee, and rubber and small holders’ plantation crops, viz., coconut, oil palm, arecanut, cashew, cocoa, and spices. The cultivation of these crops in ecologically vulnerable regions incl...

2597 Background: Programmed Cell Death 1 (PD-1) protein plays a key role in inhibiting immune responses and enhancing self-tolerance via modulation of T-cell activity, inducing T-cell apoptosis and inhibiting apoptosis of regulatory T cells. PD-L1 also plays an important role in various malignancies where it can attenuate the host immune response t...

Soil acidity is one of the critical constraints for crop productivity in tropical soils. In this research, the effectiveness of management practices on the components of acidity in coconut growing sandy and laterite soils was studied. Different management practices for ameliorating soil acidity were evaluated through experiments in randomized block...

One hundred and ten rhizobacterial isolates associated with healthy coconut palms of root (wilt) diseased tract of Kerala were isolated and screened in-vitro for IAA production and solubilization of fixed forms of mineral nutrients. Seven isolates showing multiple phytobeneficial properties were characterized and the selected isolate was tested for...

Aim: Isolation, screening and characterization of beneficial rhizosphere bacteria associated with healthy (field-resistant) coconut palms in root (wilt) disease endemic hotspot areas of Kerala. Methodology: One hundred and ten rhizobacterial isolates associated with healthy coconut palms of root (wilt) diseased tract of Kerala were isolated and scr...

Lethal wilt disease of coconut, reported as a disease of unknown etiology as early as 2007, was for the first time found consistently in association with a phytoplasma in diseased coconut trees in Thanjavur, Thiruvarur and Pudukkottai districts in Tamil Nadu on the southeastern coast of India. Nested PCR with phytoplasma-specific universal primers...

Introduction: Lysine specific demethylase 1 (LSD1) and histone deacetylases (HDACs) are known to modulate the expression of several disease specific genes as part of repressor complexes, including CoREST. In addition, they also have complex mutually exclusive roles in cancer cells. Accordingly, several studies have shown that combined inhibition of...

Introduction: Lysine Specific Demethylase 1 (LSD1) is over-expressed in many cancers and down-regulation of LSD1 has been shown to effectively treat cancers by inducing re-expression of aberrantly silenced genes. Studies have shown that LSD1 may contribute to acute myelogenous leukaemia pathogenesis by inhibiting the normal pro-differentiative func...

The unique characteristics of metal–organic frameworks such as structural tunability, high surface area, low density, and tailored porosity have made this material suitable for different applications, compared to mineralized carbons. To improve the photocatalytic activity of α-Fe2O3, a shell of carbon with different concentrations on the core of α-...

Coconut (Cocos nucifera L.) is a small holder's plantation crop cultivated predominantly in the humid tropics and tropical belts of India. Water is one of the critical inputs required in coconut production that plays important roles in growth, development and productivity. Though the coconut-growing regions in the coastal belt are endowed with high...

The effective mass of the materials relies on exciton dynamics which is greatly dominated by energy gap of the materials. We examined the effective mass for Al2O3/NiO nanoheterostructure material through polarization in dielectric study. The mean optical effective mass was calculated to be in the UV-Visible region (1x106 Hz to 5.4×106 Hz). From the...

Coconut-growing soils of Kerala: 2. Assessment of fertility and soil related constraints to coconut productionK.M. Nair*, Abdul Haris1, Jeena Mathew1, V. Srinivasan2, R. Dinesh2, H. Hamza2, P. Subramanian1, C. Thamban1, K.P. Chandran1, V. Krishnakumar1, Ravi Bhat1, R. Hegde and S.K. Singh Abstract Growth, productivity and health of coconut plantati...

The synthesized pure MgWO4 phosphor has wolframite structure with pure monoclinic phase and the cerium doped MgWO4 phosphor has a secondary phase [WO6]⁶⁻ with the formation of Ce2WO4 on sintered at 1000 °C for 4 h. FESEM shows that the grain sizes are in the range of 1–4 μm and also deformation of rod like morphology as on doping with cerium. Photo...

Different amount (3, 5, 7 and 9 mol%) of the Tantalum (Ta) doped CdS nanoparticles have been synthesized by hydrothermal approach for the photocatalytic degradation of the organic pollutant removals. The physicochemical properties of the synthesized products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTI...

First incidence of the neotropical invasive Bondar’s Nesting Whitefly (BNW), Paraleyrodes bondari Peracchi (Hemiptera: Aleyrodidae) in India is reported on coconut palms from Kerala. P. bondari constructs unique woolly wax nests on abaxial surface of palm leaflets and possesses “X”-shaped oblique greyish bands on wings. Presence of flower-petal lik...

The CdS/PbWO4 nano hetero structure photocatalyst has been successfully prepared by a hydrothermal method. The as-prepared catalyst was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), U...

Impaired insulin secretion, a characteristic of type 2 diabetes (T2D) is partly attributed to decreased β-cell mass due to apoptotic cell death under diabetogenic conditions. Current therapies for diabetes do not address apoptotic cell death mediated β-cell deterioration. Mammalian STE20-like protein kinase 1 (MST1) is reported as one of the critic...

Natural forests and managed plantations constitute the largest land-use systems in humid tropics of south-western parts of Peninsular India comprising the Western Ghats and coastal plain. Soils therein are naturally acid and the acidity is enhanced in managed land-use systems through inputs of chemical fertilizers. Plant nutrient deficiencies and m...

Natural forests and managed plantations constitute the largest land-use systems in the humid tropics of southwestern parts of Peninsular India comprising the Western Ghats and coastal plain. Soils therein are naturally acidic and the acidity is enhanced in managed land-use systems through inputs of chemical fertilizers. Plant nutrient deficiencies...

Tungsten and fluorine codoped TiO2 (W, F-TiO2) nanoparticles were synthesis by sol-gel method. The XRD analysis shows that all the samples existed as anatase phase of TiO2. Also, the crystalline size of codoped TiO2 is decreasing than the pure and monodoped TiO2. TEM images indicate that grain size of pure and codoped TiO2 nanoparticles are in the...

Marigold (Tagetus erecta) and globe amaranth (Gomphrena globosa) are two potential commercial loose flower crops with high market demand during festive seasons. Climate of coastal humid tropics is suitable for growing marigold and globe amaranth during October to April and May to September, respectively, where the flowering season coincides with th...

Root (wilt) is a very serious disease of coconut in Kerala caused by phytoplasma. Lack of preventive measures for this phytoplasmal disease demands management strategies involving multidisciplinary approaches. Managing the disease using rhizobacteria is one such strategy. Rhizosphere soil bacteria exert their beneficial role on host plants by mecha...

In the present work, silver and sulphur codoped TiO2 (Ag–S/TiO2) photocatalysts were effectively prepared by sol–gel technique. The prepared samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive x-ray analysis (EDX), Fourier transform...

In the present work, the Ni/Ce‐codoped CdS Nanoparticles (NPs) were synthesized through a hydrothermal method. The phase structure, chemical state, chemical composition, morphology and optical properties of prepared samples were characterized using X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), Energy Dispersive X‐Ray Analysis (ED...

The PD-1/PD-L1 molecular pathway is one of the primary mechanisms of immune evasion deployed by cancer cells. Induction of PD-L1 expression on cancer cells is associated with inhibition of immune responses against cancer, thus permitting cancer progression and metastasis. Activation of PD-1/PD-L1 pathway induces apoptosis of activated T-cells, inhi...

An experiment was conducted to standardize the critical boron level in soil and leaf samples of coconut palms grown in a typical Entisol of the Onattukara region of Kerala, India. Graded levels of boron as borax were applied at 0, 6, 12, 18 and 24 g per palm per year in four split doses. The critical boron level in soil and leaves was standardized...

Synthesized 4-nitro-N-(2,4-dinitrophenyl) benzenamine (NDPBA) molecule was confirmed applying the tool of NMR. Theoretical prediction addressed the NMR chemical shifts and correlated well with the experimental data. The molecule subjected to theoretical DFT at 6–311++G** level unraveled the spectroscopic and structural properties of the NDPBA molec...

The protonated organic single crystal of 4-chloroanilinium-L-tartrate monohydrate (4CALTM) was successfully grown by slow evaporation solution technique at room temperature. Powder X-ray diffraction confirmed the crystal system of the grown crystal and its lattice parameters were calculated. Microanalysis confirms the elemental compositions and the...

The enhanced photocatalytic performance of nanocomposite is synthesized via the hydrothermal method and characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR), UV–visible diffuse reflectance spectroscopy (UV–Vis DRS) an...

Scavenging action of Leiochrinus nilgirianus Kaszab (Coleoptera: Tenebrionidae) on sooty mould deposition on coconut palms due to heavy honeydew production by the invasive rugose spiralling whitefly, Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae), is reported for the first time from Kerala, India. Adult beetles, averaging 2.07 ± 0.9 /...

The natural habitat of coconut is the coastal belt of the tropics where sandy and red sandy loam soils predominate. This chapter describes the major coconut growing soils around the world, their characteristics and management. An understanding of the role of major, secondary and micronutrients and their interactions is discussed in relation to the...

Improved agro-techniques have been standardized, through research conducted over several decades, to achieve sustainable productivity and profitability in coconut farming. Adoption of refined nursery techniques enables production of quality planting material. Poly bag nursery technique with bio-priming of biofertilizer formulations helps in product...

Polymer composite films based on PVA–PVP with AlCl3 as the dopant at different concentrations were prepared using solution casting technique. XRD patterns reveal the increase in amorphousity of the films with AlCl3 doping. Optical absorption studies exhibit that the values of optical absorption coefficient, direct and indirect optical band gaps are...

Protonated organic single crystals of Benzimidazolium salicylate (BSL) were successfully grown by the slow evaporation solution technique at room temperature. The crystal structure and lattice parameters of the as-grown single crystal have been identified and calculated by the Powder X-ray Diffraction (PXRD) method. Microanalysis has confirmed the...

In this work, Mg-doped CdS prepared at different concentrations of Mg were composited with polyvinyl alcohol (PVA) for functionalization in photocatalytic process. These nanocomposites films were characterized using different physicochemical techniques. The cubic structure identification of all the nanocomposites films was carried out by the X-ray...

An extensive theoretical study on the molecular structure and vibrational analysis of 3-amino-4-methoxy benzamide (3A4MBA) was undertaken using density functional theoretical (DFT) method. The possibility of formation of intramolecular hydrogen bonding was identified from structural parameter analysis and confirmed with the natural bond orbital (NB...

Protonated 2-amino-4-methylpyridinium 4-nitrobenzoate compound was synthesised and optical quality NLO single crystals of dimension 5 × 5 × 1 mm3 was grown by isothermal solvent evaporation method. The single crystal X-ray diffraction analysis confirmed the monoclinic system with non-centrosymmetric space group Pc of the grown crystal in which the...

A 3-methoxy-4-hydroxybenzaldehyde-2,4,6-trinitrophenol (mhba-tnp) cocrystal was grown by the slow evaporation solution growth technique using ethanol as a solvent. As-grown crystals were characterized by single crystal X-ray diffraction (XRD) study and crystallized with a centrosymmetric space group. Optical properties of the grown crystal have bee...

The title compound, imidazolium 2-chloro-4-nitrobenzoate (I2C4NB), has been synthesized and optical quality single crystals were grown with a dimension of 4 x 2 x 1 mm3 using an ethanol and acetone (1:1) mixed solvent by slow evaporation solution growth technique. The powder XRD analysis confirmed the crystal structure and found that it is crystall...

In the present study, this report discusses the preparation and photocatalytic properties of pure, Ag and Zn doped and Ag–Zn codoped TiO2 nanoparticles by sol–gel method. The powder X-ray diffraction study showed that crystallite size of doped and codoped TiO2 nanoparticles was decreased compared with pure TiO2. The decreased particles size was con...

The conformational study of the 2,3,4,5 tetrafluorobenzoic acid molecule (TFBA) was performed by density functional theory (DFT) using B3LYP functional with 6–311++G(d,p) basis set. Vibrational frequencies were calculated at the same level of theory for the optimized stable structure. The existence of hydrogen bonding was predicted through experime...

Performance of vanilla, as influenced by organic source of nutrition when grown as intercrop in coconut garden, was studied in sandy loam soil at ICAR-CPCRI, Kasaragod, Kerala for seven years. Field experiments were carried out with different sources of organic manures, recommended NPK fertilizer and no fertilizer treatments. Application of cow dun...

In this work, we have studied the influence of sodium in CuZnSnS (CZTS) solar cells. The CZTS films were prepared on soda lime glass substrates with and without sodium barrier layers (the glass substrate served as a sodium source). Alternatively, a 40 nm NaF layer was deposited on the metallic precursor using glass substrates with a sodium barrier...

This work studies the effect of Cu doping on structural, morphological, optical, dielectric and photocatalytic activity of TiO2 nanoparticles. Pure and Cu doped TiO2 nanoparticles were synthesized using sol-gel technique. The powder XRD pattern confirmed that all the samples were polycrystalline of anatase phase and increasing doping concentration...

Intercropping Heliconia with coconut is remunerative Heliconia is emerging as an important cut flower in India which can be grown as intercrop in coconut gardens. At present, marketing is concentrated in domestic markets of metros which itself is fetching high profit. The scope of exporting needs to be explored. The maior constraint of exporting is...

In this work, we reported TEM observations of several CdS thin films prepared by close space submission, sputtering, chemical bath deposition and electronic deposition technologies. The CdS layers prepared by close space submission and sputtering methods had larger grains (50-80 nm), while the CdS layers deposited by chemical bath had very small gr...

Undoped, 0, 2, and 5 mol% Ce-doped ZnS–PVA nanocomposite films have been prepared using in situ chemical method. X-ray diffraction patterns confirm that the prepared nanocomposite films are in cubic structure of ZnS. UV–Vis optical absorption spectra of Ce3+-doped ZnS–PVA films exhibit the red-shifted phenomenon with the increasing Ce dopant concen...

We report few-cycle THz pulses emission from a novel organic crystal 2,6-diaminopyridinium-4-nitrophenolate-4-nitrophenol (DAP⁺NP⁻NP). The observed amplitude of the THz electric field from a DAP⁺NP⁻NP crystal is comparable with that from a ZnTe single crystal under the same optical pumping conditions. Both the waveform and spectra of the THz radiat...

The title compound Imidazolium 2-Chloro-4-nitrobenzoate (I2C4NB) has been synthesized and single crystals were grown by using mixed solvent of ethanol and acetone (1:1) by slow evaporation solution growth technique. The I2C4NB crystallizes in monoclinic crystal system with non-centrosymmetric space group of P21. The crystalline phases of I2C4NB wer...

Hydroxyethylammonium p-nitrophenolate single crystal has been grown by slow evaporation solution growth method for the first time to the best of our knowledge. The crystal structure was determined by single crystal X-ray diffraction study. Optical property was characterized using ultraviolet-visible spectroscopy technique.13C and 1H Nuclear magneti...

The FT-IR and FT-Raman spectra of 5-fluoro-2-methylbenzaldehyde (5F2MB) have been recorded in the regions 4000–400 cm⁻¹ and 4000–100 cm⁻¹, respectively. Using the observed FT-IR and FT-Raman data, a complete vibrational assignment and analysis of the fundamental modes of vibrations of the compound were carried out. The optimum molecular geometry, v...

Research was conducted during 2010-2013 at the Central Plantation Crops Research Institute, Kayamkulam, Kerala state, India, to analyse the effect of coconut shade on light use efficiency and quality of flowers of Heliconia stricta, when grown as intercrop under various nutrient management practices in sandy loam soils. Leaf characteristics, includ...

A combined experimental (infrared, Raman and NMR) and theoretical quantum chemical study is performed on the charge-transfer complex hydroxyethylammonium picrate (HEAP). The infrared (IR) spectra for HEAP were recorded at various temperatures, ranging from 16 K to 299 K, and the Raman spectrum was recorded at room temperature. A comparison of the e...

Introduction: LSD1 is a flavin adenine dinucleotide (FAD)-dependent amine oxidase that removes methyl groups from mono- or dimethylated histone H3 lysine 4. LSD1 has been reported to be overexpressed in many malignant tumors, including breast, colon, prostate, lung, gastric cancers and others. Studies have shown that LSD1 may contribute to acute my...

CdTe solar cell back contact preparation usually includes a chemical etching process which helps to obtain a Te-rich p-doped CdTe surface. In this work we compared the influence of two different etching solutions [nitric–phosphoric (NP) and nitric–acetic acid (NA)] on the CdTe surface. Transmission electron microscopy indicated that a Te-rich l...

Third-order nonlinear optical properties of Mg doped CdS-PVP films have been studied by Z-scan technique with 5 ns pulses, mod-locked Nd-YAG laser with a frequency doubled at 532 nm. The nonlinear refractive indices and nonlinear absorption coefficients were in the order of 10−10 cm2/W and 10−3 cm/W and they are characterized with self-defocusing a...

A novel 8-hydroxyquinolinium dibenzoyl-(l)-tartrate methanol monohydrate crystal has been grown by slow evaporation technique. The single crystal X-ray diffraction analysis has been done for the title compound and is found to crystallize in orthorhombic space group P212121. The optical absorption cut-off wavelength is found to be 440 nm. The vibrat...

The Vibrational and electronic properties of phenyl substituted compounds 1-(2-methoxyphenyl)piperazine and 1-(2-chlorophenyl)piperazine have been investigated by FT-IR, FT-Raman, NMR and UV-Vis spectral measurements. Density functional theory (DFT) method, using B3LYP functional, with 6-311++G (d,p) basis set, has been performed for assigning vibr...

A novel hydroxyethylammonium maleate sin-gle crystal was grown by slow evaporation solution method for the first time. The structure of the title compound is determined by single crystal X-ray diffraction. The linear optical properties were studied using ultraviolet–visible and photoluminescence spectroscopy. The third-order nonlinear optical prope...

Introduction: EGFR targeted therapies like Tarceva are very effective initially for non-small cell lung cancer (NSCLC) harboring EGFR activating mutations; but patients eventually develop resistance to these first line inhibitors and in about 50% of the cases, resistance is due to a secondary mutation T790M,leading to decreased affinity of these dr...

In this work, the vibrational characteristics of 2-Benzylpyridine have been investigated. The structure of the molecule has been optimized and the structural characteristics of the molecule have been determined by density functional theory B3LYP method with 6-31G(d,p) basis set. The infrared and Raman spectra have been simulated from calculated int...

We report on a comprehensive study of the magnetization, resistivity and heat capacity on the single crystals of Ce2RhGa12 synthesized using Ga flux. Single crystal X-ray diffraction data confirm the tetragonal Pb/nbm structure of Ce2RhGa12, which is isostructural to Ce2PdGa12. Ce2RhGa12 orders antiferromagnetically at T-N = 3.5 K and exhibits anis...

Luminescent materials have many interesting applications, however it remains difficult to control luminescence in organic materials and in particular to retain the same luminescence in solution and in the solid state, a property of interest for various imaging applications. The fluorescent properties of the 2,6 diaminopyridinium salt with dihydroge...

The 8-hydroxyquinolinium 3,5-dinitrobenzoate crystals were grown using slow evaporation solution technique. The structure was confirmed by single crystal X-ray diffraction and nuclear magnetic resonance analyses. The Fourier transform infrared and Raman spectral analyses were carried out to identify the various functional groups present in the titl...

A systematic kinetic Study of crystallization among two smectogens of higher homologues of the benzylidene aniline series nO.m, viz. 4O.12 and 8O.12, has been carried Out by thermal microscopy, differential scanning calorimetry (DSC). and dielectric studies. The crystallization kinetics was Studied by two techniques, viz. the traditional thermal an...

The presence of superstructure and impact of solvent on the formation of different forms in the simple trimorphic system of 6-chloro-2,4-dinitroaniline (CDA) are investigated in this report. The experiment was carried out as part of sorting three forms of CDA. Forms I and III were obtained by an anti-solvent precipitation method. The filtrate, i.e....

Root (wilt) disease is a major constraint to coconut production in Kerala State. Conserving ecotypes with resistance or tolerance to the disease on a community basis is essential to sustain coconut production in the root (wilt) disease prevalent areas. Three communities’viz., Pathiyoor and Devikulangara (Alappuzha District) and Thodiyoor (Kollam Di...

The FTIR and FT-Raman spectra of 1-(m-(trifluoromethyl)phenyl)piperazine [TFMPP] have been recorded in the region 4000-400cm(-1) and 3500-100cm(-1), respectively. The optimized geometry, frequency and intensity of the vibrational bands of the compound was obtained by the density functional theory using 6-311++G(d,p) basis set. The harmonic vibratio...

Maltol (3-hydroxy-2-methyl-4pyrone) is widely known as metal ions chelator with many practical applications in catalysis, medicine and food chemistry. The FTIR and FT-Raman spectra of maltol have been recorded in the region 4000-400 and 4000-50cm(-1), respectively. The conformational analysis, optimized geometry, frequency and intensity of the vibr...

Organic 2,5-dichloroanilinium picrate crystal was grown by using slow evaporation solution technique. The lattice parameter was estimated by powder X-ray diffraction. The absence of absorption at around Nd:YAG fundamental wavelength was confirmed by ultraviolet-visible absorption study. The vibrational analyses confirm the various functional groups...

Maltol (3-hydroxy-2-methyl-4pyrone) is widely known as metal ions chelator with many practical applications in catalysis, medicine and food chemistry. The FTIR and FT-Raman spectra of maltol have been recorded in the region 4000-400 and 4000-50 cm −1 , respectively. The conformational analysis, optimized geometry, frequency and intensity of the vib...

Root (wilt) disease is a major constraint to coconut production in Kerala State. Conserving ecotypes with resistance or tolerance to the disease on a community basis is essential to sustain coconut production in the root (wilt) disease prevalent areas. Three communities’viz., Pathiyoor and Devikulangara (Alappuzha District) and Thodiyoor (Kollam Di...

The FTIR and FT-Raman spectra of 2-hydroxyquinoline and its derivatives have been recorded in the region 4000-400cm(-1) and 3500-100cm(-1), respectively. The optimized geometry, frequency and intensity of the vibrational bands of these compounds were obtained by the density functional theory using 6-311++G(d,p) basis sets. The harmonic vibrational...

The FTIR and FT-Raman spectra of 2-fluoro benzamide (2FBA) have been recorded in the region 4000-400 and 4000-100cm(-1), respectively. The structuralanalysis, hydrogen bonding, optimized geometry, frequency and intensity of the vibrational bands of 2FBA were obtained by the density functional theory (DFT) with complete relaxation in the potential e...