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Articles by A. Karthikeyan
Total Records ( 7 ) for A. Karthikeyan
  A. Karthikeyan , R. Valarmathi , S. Nandini and M.R. Nandhakumar
  Insect pests have become an integral part of agricultural crops worldwide. They significantly reduce yield and affect almost every aspect of the plants. For many years major challenge for scientists has been developing the resistant varieties against pests in plants. Plant breeders have also been successful during the last century in producing a few Insect-resistant cultivars/lines of some potential crops through conventional breeding, but this again has utilized modest resources. However, this approach seems now inefficient due to a number of reasons and alternatively, genetic engineering for improving crop pest and disease resistance is being actively followed these days by the plant scientists, world-over. New tools and genes have been developed for use in the genetic engineering of plants to introduce effective resistance to biotic stresses and to understand the mechanisms of resistance. Recent advances in genetic engineering, Bacillus thuringiensis (Bt) has resulted in successful control of many economically important pests in food crops. This approach should allow increases in both productivity and quality of plants in an environmentally friendly manner, thereby reducing the use of and reliance on chemical control of pests.
  A. Karthikeyan , M. Sudha , M. Pandiyan , N. Senthil , V.G. Shobana and P. Nagarajan
  Yellow mosaic disease is one of the most important viral diseases in mungbean caused by Mungbean Yellow Mosaic Virus (MYMV) which leads to severe yield reduction and it necessitates developing MYMV resistant lines for improved crop yield. The present investigation was carried out with an objective of identification of MYMV resistant progenies through Agroinoculation. This technique was employed to examine the F2 individuals, which were derived from a cross between Vamban (Gg) 2 (susceptible) x KMG 189 (resistant) to screen for the MYMV resistant progenies. In the field condition, MYMV infection can be evaluated by MYMV disease rating scale (1-9). Out of the 203 F2 individuals, 30 individuals were identified as resistant to MYMV and subjected to agroinoculation. The two tandem viral constructs of MYMV, VA 221 (KA30 DNA A + KA22 DNA B) and VA 239 (KA30 DNA A + KA27 DNA B) mobilized in Agrobacterium tumefaciens strains Ach 5 and C 58 were used for Agroinoculation. The results shows that among the thirty individuals, only five individuals namely MYMVR 10, MYMVR 13, MYMVR 15, MYMVR 17 and MYMVR 37 exhibited resistance to VA 221 strain and found to be susceptible to VA 239 strain. Other twenty five individuals are susceptible to both strains, VA 221 and VA 239. The presence of viral DNA in agroinoculated plants were confirmed by Reverse Transcriptase-Polymerase Chain Reaction (PCR) analysis. For additional corroboration, these five resistant individuals are forwarded to F3 generation and confirmed for resistance in field condition.
  A. Karthikeyan and K. Balamurugan
  This study is aimed at to investigate the effect of surface modification through NaOH (Sodium hydroxide) treatment and fiber length on the tensile strength of coir fiber of reinforced epoxy composites. The coir fibers was treated with 2, 4, 6, 8 and 10% concentration of NaOH separately for 10 days.The tensile strength of untreated and alkali treated fiber was measured. For each group of the coir fiber experiments were conducted on different fiber lengths, namely; 10, 20 and 30 mm. The experimental results showed that increasing NaOH concentration leads to a decrease in fiber diameter in a linear fashion. This reduction in diameter naturally ends up with reduced tensile strengths. The treated coir fiber was used as a reinforcement and epoxy as a matrix to fabricate the composites. The tensile strength of different samples of composites was measured. Increased NaOH concentration in fibers treatment was found to increase the tensile strength up to 4% and further increase in NaOH concentration reduces the tensile strength and also increased fiber length was found to increase in tensile strength. Maximum tensile strength of the composite was found to be uniformly accruing for 4% NaOH treated samples. Based on the nonlinear regression analysis the tensile strength equation was proposed for coir fiber reinforced epoxy composites.
  A. Karthikeyan , T. Muthukumar and I. Sureka
  Blister bark caused by Trichosporium vesiculosum Butl. is a lethal fungal disease of Casuarina equisetifolia Forst. In plantations, blister bark is more prevalent in trees that are more than two and a half years old. So in this present study, the influence of climatic and edaphic factors on blister bark disease development in C. equisetifolia under controlled conditions were investigated. The pathogen isolated from the disease plant tissues was maintained on Potato Dextrose Agar medium. Conidial suspension of the pathogen was inoculated onto 3 to 6 months old. C. equisetifolia seedlings raised on different soil types (Alfisol, Vertisol and Ultisol). The pathogenecity study indicated that T. vesiculosum attacked C. equisetifolia seedlings as early as 5 months old. A temperature range of 25 to 30°C and a relative humidity (%) range of 45 to 60 favoured the conidial development and fungal spread in the seedlings. Similarly soil pH of 5.5 to 6 favoured the pathogen and disease development whereas soil pH<7.5 deters disease development. It was also found that regular watering prevented disease development. Soil type seems to play a major role in disease development as disease incidence and severity was more in seedlings raised in Vertisol than in other soil types. From this experiment it was understood that the favourable temperature, soil factors and soil type for this pathogen to be taken care at the time of planting of C. equisetifolia seedlings so as to avoid the blister bark disease.
  A.C. Liju , A. Karthikeyan , N.B. Siva Priya and Sadia Siddiqui
  The biocontrol potential of Trichoderma viride against anthracnose pathogen Colletotrichum alienum was studied in vitro and under greenhouse conditions. In vitro antagonism test carried out between T. viride and C. alienum showed a radial growth inhibition of the pathogen by 75% at 35°C. The greenhouse studies involved inoculation of healthy Swietenia macrophylla seedlings with suspensions of T. viride and fungicide (Carbendiazim) followed by addition of the pathogen, C. alienum inoculum after three days. After inoculation the infected leaf area was measured weekly and Area under the Disease Progress Curve (AUDPC) was calculated and compared among the treatments. The results showed that T. viride (AUDPC = 120) and fungicide (AUDPC = 93) significantly (p<0.05) reduced the disease compared to the untreated control (AUDPC = 1200). T. viride significantly controlled the pathogen on par with fungicide treatment. This study revealed that the application of T. viride has good potential in controlling the anthracnose disease of S. macrophylla.
  Akanksha Mohan Gupte , Suryalok Sarkar and A. Karthikeyan
  The energy efficiency and optimization of network lifetime are the most important design criterion in Wireless Sensor Networks (WSNs). This is because WSNs are equipped with limited non-restorable supply of energy. In this study, a Double Cluster Head Clustering Algorithm is presented whose basis is Particle Swarm Optimization (PSO). In this algorithm, two cluster heads namely the Primary Cluster Head (PCH) and the Secondary Cluster (SCH) are generated. PCH is used to receive and aggregate data from its cluster member nodes and send the aggregated data to SCH. SCH then transmits this aggregated data to base station directly. For larger networks this algorithm certainly improves the basic PSO as there is a division of work load among the cluster heads which results in balanced energy utilization throughout the network. This protocol is then compared with various extended versions of LEACH protocol and the effect of all these protocols is studied collectively to optimize the network lifetime.
  A. Karthikeyan and K.M. Sakthivel
  Eucalyptus camaldulensis Dehn is a commercial tree crop mainly for paper and pulp industries. This tree crop is propagated by vegetative propagation method to obtain genetically superior clones. At the time of vegetative propagation a synthetic rooting hormone Indole Butyric Acid (IBA) is being used in nurseries for successful rooting in E. camaldulensis stem cuttings. To reduce the cost of IBA and improve the rooting and nutrient enrichment as an alternate method a nitrogen fixing bacteria Azotobacter chroococcum was applied in the stem cuttings of E. camaldulensis in present study. The influence of A chroococcum on rooting and subsequent growth of E. camaldulensis cuttings was observed under nursery conditions. An un-inoculated control and IBA treated cuttings were also maintained to compare the growth with A. chroococcum inoculated stem cuttings. Bacterial inoculum (5x107 cfu mL-1 ) at the rate of 5 and 10 mL were applied to the rooting substrate (vermiculite) during cutting installation. Rooting and Biomass was evaluated after 30 days of cutting installation. Additionally, the isolates were screened for their ability to produce Indole Acetic Acid (IAA) under in vitro conditions either in the presence or absence of tryptophan at different concentrations. The results revealed that A. chroococcum produced significant quantities of IAA for root initiation and A. chroococcum inoculated cuttings had higher growth than IBA treated cuttings at p<0.05. From this study, it was concluded that the stem cuttings of E. camaldulensis responded positively to A. chroococcum inoculation through increased root proliferation and growth.
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