Browsing by Author "Daniel, E.V."
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Item Changes in Chlorophyll fluorescence during cocoa leaf development(2007-02-08) Balasimha, D.; Daniel, E.V.Item Chlorophyll fluorescence and gas exchange characteristics of cocoa(2007-02-08) Balasimha, D.; Daniel, E.V.The chlorophyll fluorescence, net photosynthesis (Pn) and related stomatal characters were studied in cocoa trees. There were significant seasonal variations in chlorophyll fluorescence indices and gas exchange characteristics in cocoa. The F0 value was significantly higher in drought susceptible accession type showing that. PS II was affected to a greater extent. However, Fm and Fv were lower in drought tolerant trees as compared to susceptible ones. This was in parallel with lower Pn in tolerant type. Drought tolerant accession had higher stomatal diffusive resistance resulting in decreased transpiration rate. The rs was negatively correlated with transpiration. These fluorescence signatures reflect on the intactness of the photosystems even at closed stomata in tolerant types during stress periods. The relationships between Pn and fluorescence quenching parameters have also been studied.Item Comparative drought tolerance of cacao accessions(2007-02-08) Balasimha, D.; Rajagopal, V.; Daniel, E.V.; Nair, R.V.; Bhagavan, S.Item Epicuticular waxes, lipids and membrane stability of cocoa trees in relation to drought tolerance(2007-02-08) Prakash G. Bhat; Daniel, E.V.; Balasimha, D.Higher leaf turgor was maintained in tolerant accession types of cocoa during dry periods which was accompanied by higher wax deposition. There were however no qualitative changes in wax composition between accession types. The lipid content decreased due to stress. Degree of unsaturation was lower, and total sterol/phospholipid ratio was higher with lower electrolytic leaching in tolerant accessions as compared to susceptible ones, especially under stress. All these changes in wax and lipid fractions help cocoa in better adaptation to drought by improving membrane stability.Item Influence of environmental factors on photosynthesis in cocoa trees(Elsevier Science Publishers B.V., Amsterdam, 1991) Balasimha, D.; Daniel, E.V.; Prakash G. BhatThe photosynthesis of cocoa (Theobroma cacao Linn.) as influenced by light temperature and vapour pressure deficit (VPD)was studied in the field. Net photosynthetic rate (PN), transpiration rate and stomatal conductance showed significant seasonal variations. PN was highest during periods of low evaporative demand (low VPD). Diurnal patterns of these parameters indicated transient midday water deficits which reduced PN. Optimum temperature for PN was 31-33C and light saturation occurred at 400 μmol m-2 s-1. The CO2, compensation concentration was 100 ppm. Drought tolerant accessions maintained higher leaf water potential than drought-susceptible types in dry months. There was no significant difference in PN between tolerant and susceptible accession types.Item A Screening Method For Drought Tolerance In Cocoa(1988) Balasimha, D.; Daniel, E.V.Item Water relations and net photosynthesis of arecanut palms affected with yellow leaf disease(1993) Chowdappa, P.; Balasimha, D.; Daniel, E.V.