Rajan R.,Rubber Research Institute of India |
Varghese S.,Rubber Research Institute of India |
George K.E.,Cochin University of Science and Technology
Rubber Chemistry and Technology | Year: 2013
The drawbacks of peroxide vulcanization can largely be overcome by introducing suitable co-curing agents (coagents) in the formulation. The role of various coagents, such as zinc diacrylate (ZDA), trimethylolpropane trimethacrylate (TMPTMA), and triallyl cyanurate (TAC) in the peroxide vulcanization of natural rubber (NR) was studied by Fourier transform infrared spectroscopy. Cross-link density was measured by the equilibrium-swelling technique. Cross-linking mechanism of peroxide in NR was interpreted by comparing the spectra of cured and uncured vulcanizates. The predominance of hydrogen abstraction over the radical addition was established (at 160 °C). CoagentZDAproduces ionic as well as covalent cross-links in the vulcanizate. Ionic cross-links have the ability to slip along the hydrocarbon chains and thus resemble polysulfidic cross-links. Hence, ZDA can be chosen for applications where good mechanical properties are required. Coagent TMPTMA produces covalent cross-links between polymer chains and is suitable for high-modulus applications. TAC, although it bridges through covalent cross-links, is not a suitable coagent for highly unsaturated rubbers like NR.
Mkhabela M.S.,University of Manitoba |
Bullock P.,University of Manitoba |
Raj S.,Rubber Research Institute of India |
Wang S.,Canada Center For Remote Sensing |
Yang Y.,Canada Center For Remote Sensing
Agricultural and Forest Meteorology | Year: 2011
Although Normalised Difference Vegetation Index (NDVI) data derived from the advanced very high resolution radiometer (AVHRR) sensor have been extensively used to assess crop condition and yield on the Canadian Prairies and elsewhere, NDVI data derived from the new moderate resolution imaging spectroradiometer (MODIS) sensor have so far not been used for crop yield prediction on the Canadian Prairies. Therefore, the objective of this study was to evaluate the possibility of using MODIS-NDVI to forecast crop yield on the Canadian Prairies and also to identify the best time for making a reliable crop yield forecast. Growing season (May-August) MODIS 10-day composite NDVI data for the years 2000-2006 were obtained from the Canada Centre for Remote Sensing (CCRS). Crop yield data (i.e., barley, canola, field peas and spring wheat) for each Census Agricultural Region (CAR) were obtained from Statistics Canada. Correlation and regression analyses were performed using 10-day composite NDVI and running average NDVI for 2, 3 and 4 dekads with the highest correlation coefficients (r) as the independent variables and crop grain yield as the dependent variable. To test the robustness and the ability of the generated regression models to forecast crops grain yield, one year at a time was removed and new regression models were developed, which were then used to predict the grain yield for the missing year. Results showed that MODIS-NDVI data can be used effectively to predict crop yield on the Canadian Prairies. Depending on the agro-climatic zone, the power function models developed for each crop accounted for 48 to 90%, 32 to 82%, 53 to 89% and 47 to 80% of the grain yield variability for barley, canola, field peas and spring wheat, respectively, with the best prediction in the semi-arid zone. Overall (54 out of 84), the % difference of the predicted from the actual grain yield was within ±10%. On the whole, RMSE values ranged from 150 to 654, 108 to 475, 204 to 677 and 104 to 714kgha-1 for barley, canola, field peas and spring wheat, respectively. When expressed as percentages of actual yield, the RMSE values ranged from 8 to 25% for barley, 10 to 58% for canola, 10 to 38% for field peas and 6 to 34% for spring wheat. The MAE values followed a similar trend but were slightly lower than the RMSE values. For all the crops, the best time for making grain yield predictions was found to be from the third dekad of June through the third dekad of July in the sub-humid zone and from the first dekad of July through the first dekad of August in both the semi-arid and arid zones. This means that accurate crop grain yield forecasts using the developed regression models can be made one to two months before harvest. © 2010 Elsevier B.V.
Abraham A.,Rubber Research Institute of India |
Philip S.,Rubber Research Institute of India |
Kuruvilla Jacob C.,Rubber Research Institute of India |
Jayachandran K.,Mahatma Gandhi University
BioControl | Year: 2013
Bacterial endophytes offer control against many diseases of crop plants as potential biocontrol agents. Antagonistic bacterial endophytes acting against Phytophthora meadii have been screened from leaf, petiole and root tissues of Hevea brasiliensis. Six bacterial endophytes could exhibit more than 50 % inhibition of P. meadii, among which EIL-2, from disease-free zones showed a maximum of 62.5 % inhibition. The isolate EIL-2 was characterized as Alcaligenes sp. and the other isolates were identified as Pseudomonas aeruginosa. 16S rDNA sequence analysis showed that there existed genetic variation among the five isolates of P. aeruginosa from different tissues of the plant indicating the tissue type adaptation of the isolates. Dual culture technique with endophyte EIL-2 completely arrested the growth of P. meadii when inoculated prior to pathogen. The bioassay with EIL-2 in H. brasiliensis clones, RRII 105 showed 43 % reduction of lesion size on infected leaves whereas in RRIM 600 it was only 30 %. © 2013 International Organization for Biological Control (IOBC).
Pratheesh P.T.,Mahatma Gandhi University |
Vineetha M.,Rubber Research Institute of India |
Kurup G.M.,Kerala University
Molecular Biotechnology | Year: 2014
Algal-based recombinant protein production has gained immense interest in recent years. The development of algal expression system was earlier hindered due to the lack of efficient and cost-effective transformation techniques capable of heterologous gene integration and expression. The recent development of Agrobacterium-mediated genetic transformation method is expected to be the ideal solution for these problems. We have developed an efficient protocol for the Agrobacterium-mediated genetic transformation of microalga Chlamydomonas reinhardtii. Pre-treatment of Agrobacterium in TAP induction medium (pH 5.2) containing 100 μM acetosyringone and 1 mM glycine betaine and infection of Chlamydomonas with the induced Agrobacterium greatly improved transformation frequency. This protocol was found to double the number of transgenic events on selection media compared to that of previous reports. PCR was used successfully to amplify fragments of the hpt and GUS genes from transformed cells, while Southern blot confirmed the integration of GUS gene into the genome of C. reinhardtii. RT-PCR, Northern blot and GUS histochemical analyses confirm GUS gene expression in the transgenic cell lines of Chlamydomonas. This protocol provides a quick, efficient, economical and high-frequency transformation method for microalgae. © 2013 Springer Science+Business Media.
Purushothaman S.,Sree Chitra Tirunal Institute for Medical Science and Technology |
Sathik M.M.,Rubber Research Institute of India |
Nair R.R.,Sree Chitra Tirunal Institute for Medical Science and Technology
Journal of Cardiovascular Pharmacology | Year: 2011
Prevention of left ventricular hypertrophy remains a challenge in the prevention of hypertension-induced adverse cardiac remodeling. Cardiac hypertrophy is associated with a shift in energy metabolism from predominantly fatty acid to glucose with a corresponding reduction in the expression of fatty acid oxidation enzyme genes. Although initially adaptive, the metabolic switch seems to be detrimental in the long run. This study was taken up with the objective of examining whether the stimulation of fatty acid oxidation by the activation of peroxisome proliferator-activated receptor alpha (PPARα), a key regulator of fatty acid metabolism, can prevent cardiac hypertrophy. Fenofibrate was used as the PPARα agonist. Spontaneously hypertensive rats (SHRs) in the initial stages of hypertrophy (2 months) and those with established hypertrophy (6 months) were treated with fenofibrate (100 mg•kg•d for 60 days). Cluster of differentiation 36 (CD36)-responsible for myocardial fatty acid uptake, carnitine palmitoyl transferase 1β-a mitochondrial transporter protein and medium chain acyl-Co-A dehydrogenase-a key enzyme in beta oxidation of fatty acids were selected as indicators of fatty acid metabolism. Hypertrophy was apparent at 2 months and metabolic shift at 4 months of age in SHRs. The treatment prevented cardiac remodeling in young animals but aggravated hypertrophy in older animals. Hypertrophy showed a positive association with malondialdehyde levels and cardiac NF-κB gene expression, signifying the role of oxidative stress in the mediation of hypertrophy. Expression of carnitine palmitoyl transferase 1β and medium chain acyl-Co-A dehydrogenase was upregulated on treatment. However, CD36 showed an age-dependent variation on treatment, with no change in expression in young rats and downregulation in older animals. It is inferred that the stimulation of PPARα before the initiation of metabolic remodeling may prevent cardiac hypertrophy, but reactivation after the metabolic adaptation aggravates hypertrophy. Whether the downregulation of CD36 is mediated by decreased substrate availability remains to be explored. Age-dependent paradoxical effect on the heart in response to fenofibrate, used as a lipid-lowering drug, can have therapeutic implications. © 2011 Lippincott Williams & Wilkins.
Narayanan C.,Rubber Research Institute of India
Silvae Genetica | Year: 2011
Heritability and interactions of yield and growth traits were assessed in Hevea brasiliensis using full-sib progenies and clonal populations. Using parent-offspring regression, annual mean rubber yield (ARY) and summer yield (SY) showed moderate to high heritability (ARY, h 2 =34-56%; SY, h 2 =36-52%). Among the yield components, girth exhibited low to moderate heritability (h 2 =17-36%) while branching height showed low heritability (h 2 =18%). Using forty clonal genotypes, annual mean rubber yield (H 2=48%), rubber yield during peak period (H 2=47%) and rubber yield during stress (or summer yield) (H 2=44%) showed high estimates of heritability. Among the other yield components, except volume of latex during stress period (H 2=40%), remaining yield components showed moderate estimates for heritability (H 2=29-37%). Dry rubber content (DRC) based on annual mean showed very high heritability (H 2=68%), followed by DRC during stress (H 2=51%) and peak (H 2=50%) periods. Latex flow rate based on annual mean and peak period data showed high heritability (H 2=51%) followed by latex flow rate during stress period (H 2=42%). Plugging indices of annual and stress period showed high heritability (H 2=43%) than that of peak period (H 2=25%). Regarding growth traits, girth showed high heritability (H 2=50%) than girth increment (H 2=32%). While bark thickness showed high heritability (H 2=40%) length of tapping panel showed moderate heritability (H 2=27%). Total chlorophyll content exhibited moderate heritability (H 2=22%); chlorophyll pigment ratio showed low heritability (H 2=5%). Based on parent-offspring analysis, annual mean rubber yield exhibited high genetic correlation with summer yield and girth. Annual mean rubber yield and summer yield were negatively correlated with branching height. Regarding phenotypic correlations among the forty clonal genotypes, annual mean rubber yield exhibited high correlation with latex volume, latex flow rate, DRC, girth and bark thickness. However, annual mean rubber yield was negatively correlated with yield depression under stress and plugging index. Rubber yield, volume and rate of flow of latex over the three periods, yield depression under stress, girth increment, annual mean plugging index and plugging index under stress showed high estimates of genetic advance. The high estimates of heritability for yield and its components coupled with their high genetic gain indicated that considerable improvement can be achieved for these traits through selection. Estimates for indirect selection efficiency were not optimal for indirect selection for yield using girth and summer yield.
Uthup T.K.,Rubber Research Institute of India |
Ravindran M.,Rubber Research Institute of India |
Bini K.,Rubber Research Institute of India |
Thakurdas S.,Rubber Research Institute of India
Molecular Plant | Year: 2011
Cytosine methylation is a fundamental epigenetic mechanism for gene-expression regulation and development in plants. Here, we report for the first time the identification of DNA methylation patterns and their putative relationship with abiotic stress in the tree crop Hevea brasiliensis (source of 99% of natural rubber in the world). Regulatory sequences of four major genes involved in the mevalonate pathway (rubber biosynthesis pathway) and one general defense-related gene of three high-yielding popular rubber clones grown at two different agroclimatic conditions were analyzed for the presence of methylation. We found several significant variations in the methylation pattern at core DNA binding motifs within all the five genes. Several consistent clone-specific and location-specific methylation patterns were identified. The differences in methylation pattern observed at certain pivotal cis-regulatory sites indicate the direct impact of stress on the genome and support the hypothesis of site-specific stress-induced DNA methylation. It is assumed that some of the methylation patterns observed may be involved in the stress-responsive mechanism in plants by which they adapt to extreme conditions. The study also provide clues towards the existence of highly divergent phenotypic characters among Hevea clones despite their very similar genetic make-up. Altogether, the observations from this study prove beyond doubt that there exist epigenetic variations in Hevea and environmental factors play a significant role in the induction of site-specific epigenetic mutations in its genome. © The Author 2011. Published by the Molecular Plant Shanghai Editorial Office in association with Oxford University Press on behalf of CSPB and IPPE, SIBS, CAS.
Chandrasekhar T.R.,Rubber Research Institute of India
Journal of Rubber Research | Year: 2015
Leaf growth dynamics may have a bearing on plant performance as they are the major organs of carbon acquisition. Aim of this work was to model leaflet elongation pattern and to determine relationship of function parameters/derived growth quantities with growth performance in Hevea trees. Data were collected from randomly selected six leaflets of three trees from each of nine clones and Richards function was fitted. Growth quantities, critical points and their coordinates were computed and correlated with girth of clones. Leaflet elongation followed a similar pattern irrespective of clone and its duration was short in stress-free period than stress period. Most of the correlations were negative except that of second derivative, duration of linear and plateau phases. None of the stress period correlations were significant. Variation in leaf elongation rates of individual leaflets appeared to be due to variation in rate of cell division and/or cell elongation. All the sampled leaves of a clone followed a very similar growth pattern suggesting common duration in leaf emergence to full leaf expansion of all the leaves in a given whorl irrespective of leaf size. Significant correlation observed for y-axis intercept of phase change point from lag to linear might be useful in identifying high growth clones.
Chandrasekhar T.R.,Rubber Research Institute of India
Journal of Forestry Research | Year: 2012
No attempt has been made to date to model growth in girth of rubber tree (Hevea brasiliansis). We evaluated the few widely used growth functions to identify the most parsimonious and biologically reasonable model for describing the girth growth of young rubber trees based on an incomplete set of young age measurements. Monthly data for girth of immature trees (age 2 to 12 years) from two locations were subjected to modelling. Re-parameterized, unconstrained and constrained growth functions of Richards (RM), Gompertz (GM) and the monomolecular model (MM) were fitted to data. Duration of growth was the constraint introduced. In the first stage, we attempted a population average (PA) model to capture the trend in growth. The best PA model was fitted as a subject specific (SS) model. We used appropriate error variance-covariance structure to account for correlation due to repeated measurements over time. Unconstrained functions underestimated the asymptotic maximum that did not reflect the carrying capacity of the locations. Underestimations were attributed to the partial set of measurements made during the early growth phase of the trees. MM proved superior to RM and GM. In the random coefficient models, both Gf and G0 appeared to be influenced by tree level effects. Inclusion of diagonal definite positive matrix removed the correlation between random effects. The results were similar at both locations. In the overall assessment MM appeared as the candidate model for studying the girth-age relationships in Hevea trees. Based on the fitted model we conclude that, in Hevea trees, growth rate is maintained at maximum value at t0, then decreases until the final state at dG/dt ≥0, resulting in yield curve with no period of accelerating growth. One physiological explanation is that photosynthetic activity in Hevea trees decreases as girth increases and constructive metabolism is larger than destructive metabolism. © 2012 Northeast Forestry University and Springer-Verlag Berlin Heidelberg.
Rubber Research Institute of India | Date: 2012-07-25
The present invention relates to a process for preparing tri-filler incorporated natural rubber master batch. The fillers used in the present invention are carbon black, silica and nano-clay (modified montmorillonite clay, Cloisite 93 A). The process of preparing fillers incorporated master batch involves preparation of the individual filler dispersions by mixing each filler with surfactants. Further fresh rubber latex is soap sensitized by mixing it with surfactant. The filler dispersions are added to the soap sensitized rubber latex slowly under stirring to form the master mix. Then the master mix is coagulated by the addition of acid to form coagulum. The coagulum is dewatered and dried to obtain filler incorporated natural rubber master batch.