Effects of cadmium on growth of Helianthus annuus seedlings: physiological aspects |
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Authors: | R. DI CAGNO,L. GUIDI,A. STEFANI,& G. F. SOLDATINI |
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Affiliation: | Scuola Superiore di Studi Universitari e di Perfezionamento 'S. Anna', Via Carducci 40, 56100 Pisa, Italy; Dipartimento di Chimica e Biotecnologie Agrarie, Universitàdegli Studi di Pisa, Via del Borghetto 80, 56124 Pisa, Italy; Author for correspondence (fax +39 050 598614;e-mail;). |
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Abstract: | Sunflower seedlings ( Helianthus annuus hybrid Select) were grown in a complete nutrient solution in the absence or presence of Cd2+ (10 and 20 μM). Analyses were performed to establish whether there was a differential effect of Cd2+ on mature and young leaves. After 7 d the growth parameters as well as the leaf area had decreased in both mature and young leaves. Accumulation of Cd2+ in the roots exceeded that in the shoots. Seedlings treated with Cd2+ exhibited reduced contents of chlorophyll and CO2 assimilation rate, with a greater decrease in young leaves. The photochemical efficiency of photosystem II (PSII) was not altered by Cd2+ treatment in either mature or young leaves, although during steady-state photosynthesis in young leaves there was a significant alteration in the following parameters: quantum yield of electron transport by PSII (ΦPSII), photochemical quenching ( q P), non-photochemical quenching ( q NP), and excitation capture efficiency of PSII (Φexc). |
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Keywords: | chlorophyll fluorescence gas exchange relative water content Cd2+ toxicity stomatal conductance sunflower |
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