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20151
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Subject: Crop Physiology × Author: Das, Sangita × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Interactive effect of elevated carbondioxide and temperature on physiological characterisation of bhoot jolokia (Capsicum chinense Jacq.)
    (AAU, Jorhat, 2015) Das, Sangita; Das, Ranjan
    A study was conducted during 2012-2014 in Carbondioxide Temperature Gradient Tunnels (CTGTs) and in ambient condition to assess the interaction effect of elevated carbondioxide and temperature in two cultivars of Capsicum chinense Jacq. The treatments consisted of field (ambient CO2 and ambient temperature), CTGT I (380 ppm CO2 and ambient temperature), CTGT II (550 ppm CO2 with ambient temp. + 20 C elevation) and CTGT III (750 ppm CO2 with ambient temp. + 40C elevation). The elevation of temperature as compared to ambient was maintained from flower bud initiation to maturity stage. The results revealed that CTGT II had a greater impact on the various morpho physiological parameters viz. plant height, leaf number, branch number, plant spread, leaf area index, leaf area duration, specific leaf weight, root: shoot ratio, relative leaf water content, water potential, osmotic potential, C: N ratio, photosynthesis and chlorophyll stability index. However, at a higher CO2 and temperature in CTGT III, most of the above parameters showed a declining trend indicating the deleterious effect of high temperature. But, some parameters viz. senescence index, stomatal conductance and transpiration rate were significantly reduced at CTGT II. The phyllochron index was significantly reduced in both the elevated CO2 and temperature treatments. Similarly in biochemical parameters viz. accumulation of sugars, starch, total non structural carbohydrate, proline, antioxidant enzymes, capsaicin content showed a significantly higher value in both CTGTs as compared to ambient condition. A decline in pigments content of leaves such as chlorophyll and carotenoid were observed under both the CTGTs. A better status of membrane was recorded at CTGT II as compared to CTGT III and ambient condition in terms of lower activity of lipoxygenase, MDA (Lipid peroxidation) and H2O2 content and relative stress injury; hence a higher value of membrane stability index was recorded in CTGT-II. An enhancement in flowering was observed in both the elevated CO2 and temperature than ambient condition. Anatomical studies revealed better pollen characters; stem xylem and phloem status in CTGT II when compared to CTGT III. RT PCR data showed up-regulation of some genes viz. photosynthetic genes, antioxidant genes and capsaicin synthase gene under both the CTGTs. Better yield attributing parameters were recorded in CTGT II as compared to CTGT III and other treatments, which could be correlated to a higher percent of fruit dropping in CTGT III. Reduction due to high temperature in terms of above parameters was ameliorated under CTGT II. From the above experiment, it is evident that some degree of tolerance exhibited against high temperature stress which could be attributed to higher accumulation of carbohydrate, proline, adjustment of anatomical features, modification of antioxidant pool, better water status, lower fruit drop percent, in cv. Manipur as compared to cv. Assam under elevated carbondioxide and temperature condition. This indicates the differential responses of genotypes under future climate change conditions.