Quantification of the photosynthetic performance of phosphorus-deficient Sorghum by means of chlorophyll-a fluorescence kinetics

Ripley, B.S. and Redfern, S.P. and Dames, J.F. (2004) Quantification of the photosynthetic performance of phosphorus-deficient Sorghum by means of chlorophyll-a fluorescence kinetics. South African Journal of Science, 100 (11 & 12). pp. 615-618. ISSN 0038-2353




Chlorophyll fluorescence induction curves have been used as a sensitive tool for screening the photosynthetic performance of plants. Experimental treatments involving nitrate supply and chilling stress have been shown to affect fluorescence induction curves and other measures of photosynthesis. We have investigated the photosynthetic performance of Sorghum bicolor supplied with Long Ashton growth solution containing standard (20 μmol mol^(–1)) or low (5 μmol mol^(–1)) phosphorus. The JIP-test based on the chlorophyll fluorescence induction curve was used as a non-destructive method to measure the relative proportions of energy dissipated by different processes (termed energy fluxes) in the light reactions. The various energy fluxes or derived parameters were compared to find the measures that were most sensitive to the experimental conditions. Plant response to treatments was first evident in selected chlorophyll fluorescence parameters, particularly performance index (PI_ABS_); plants with increased PI_ABS_ manifested higher electron transport activity and dissipated less energy as heat, possibly as a result of their better phosphorus status, leading to more functional reaction centres. Observed changes in fluorescence were correlated to changes in gas exchange and biomass. Standard phosphorus treatments significantly increased biomass, leaf area, photosynthetic and respiratory rates, carboxylation efficiencies and levels of ribulose biphosphate regeneration rates, relative to plants with low supplies of nutrients.

Item Type:Article
Additional Information:Rhodes Centenary issue
Uncontrolled Keywords:chlorophyll fluorescence, Sorghum bicolor, phosphorus treatments
Subjects:Y Unknown > Subjects to be assigned
Divisions:Faculty > Faculty of Science > Biochemistry, Microbiology & Biotechnology
Faculty > Faculty of Science > Botany
ID Code:121
Deposited By: Rhodes Library Archive Administrator
Deposited On:05 Oct 2006
Last Modified:06 Jan 2012 16:17
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