Browsing by Author "George Thomas"

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    Canopy architecture, photosynthesis and yield of irrigated cocoa
    (2007-02-08) George Thomas
    An optimum canopy architecture, density and shape of cocoa should be maintained to be accommodated in the available light and air space of arecanut or coconut based high density multispecies cropping system. In a tree like cocoa with large horizontally inclined leaves, many leaves receive light far below the light compensation point. The removal of these 'parasitic leaves' which require import of photo-assimilates from other leaves to meet their growth and maintenance may increase the partition of photoassimilate to the economic product. The removal of bottom shaded branches can facilitate agronomic practices like weeding, spraying and also harvesting. Besides, though farmers do give pruning to cocoa once in an year; systematic study on pruning effects on physiological and biochemical characters and yield have not been done. With this in view, a study was carried out to evolve an optimum canopy architecture and density of cocoa by giving different levels of pruning. Five different types of pruning (unpruned control T1 , unpruned double storied T2 , pruned cone shaped T3, severely pruned T4 , and pruned flat spreading canopy T5 ) were given during September 1988 and the physiological and biochemical characters, photosynthetic behaviour, light interception efficiency, growth characters and yield were studied. Observations were made thrice in an year viz at the onset of flowering (October/November 1988 -S2) at the time of peak pod load (March/April 1989 S2 ) and just after the completion of harvesting (September 1989 - S3 ) for all characters excepting growth characters and yield. Growth measurements were taken twice; once at the beginning of the experiment just after pruning and the other at the end of the experimental period. Annual yield of pods was recorded. Due to pruning (T3,T4 and Ts ) the canopy area and number of bearing branches were significantly reduced. A significantly low light interception efficiency with a correspondingly high PAR.
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    Whole Genome Sequencing and Analysis of Plant Growth Promoting Bacteria Isolated from the Rhizosphere of Plantation Crops Coconut, Cocoa and Arecanut
    (2014-08) Alka Gupta; Murali Gopal; George V. Thomas; Vinu Manikandan; John Gajewski; George Thomas; Somasekar Seshagiri; Stephan C. Schuster; Preeti Rajesh; Ravi Gupta
    Coconut, cocoa and arecanut are commercial plantation crops that play a vital role in the Indian economy while sustaining the livelihood of more than 10 million Indians. According to 2012 Food and Agricultural organization’s report, India is the third largest producer of coconut and it dominates the production of arecanut worldwide. In this study, three Plant Growth Promoting Rhizobacteria (PGPR) from coconut (CPCRI-1), cocoa (CPCRI-2) and arecanut (CPCRI-3) characterized for the PGP activities have been sequenced. The draft genome sizes were 4.7 Mb (56% GC), 5.9 Mb (63.6% GC) and 5.1 Mb (54.8% GB) for CPCRI-1, CPCRI-2, CPCRI-3, respectively. These genomes encoded 4056 (CPCRI-1), 4637 (CPCRI-2) and 4286 (CPCRI-3) protein-coding genes. Phylogenetic analysis revealed that both CPCRI-1 and CPCRI-3 belonged to Enterobacteriaceae family, while, CPCRI-2 was a Pseudomonadaceae family member. Functional annotation of the genes predicted that all three bacteria encoded genes needed for mineral phosphate solubilization, siderophores, acetoin, butanediol, 1-aminocyclopropane- 1-carboxylate (ACC) deaminase, chitinase, phenazine, 4-hydroxybenzoate, trehalose and quorum sensing molecules supportive of the plant growth promoting traits observed in the course of their isolation and characterization. Additionally, in all the three CPCRI PGPRs, we identified genes involved in synthesis of hydrogen sulfide (H2S), which recently has been proposed to aid plant growth. The PGPRs also carried genes for central carbohydrate metabolism indicating that the bacteria can efficiently utilize the root exudates and other organic materials as energy source. Genes for production of peroxidases, catalases and superoxide dismutases that confer resistance to oxidative stresses in plants were identified. Besides these, genes for heat shock tolerance, cold shock tolerance and glycine-betaine production that enable bacteria to survive abiotic stress were also identified.