Carbon isotope discrimination in irrigated and droughted potato (Solanum tuberosum L.) |
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Authors: | R A JEFFERIES D K L MACKERRON |
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Institution: | Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK |
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Abstract: | Carbon isotope discrimination (Δ) was measured in irrigated and droughted potato. Under irrigation, Δ in leaflets at given nodes increased (P < 0.001) between 21 and 63 d after emergence (DAE), which was attributed to increasing stomatal conductance (gs) during leaf expansion. The effect of leaf position on Δ was non-significant in mature leaves. Under drought, Δ decreased (P < 0.001) in successive leaves up the stem, reflecting changes in gs and water stress. At each node Δ remained constant or decreased, suggesting that effects of water stress were greater than changes with leaf expansion. There were significant differences in Δ between cultivars in both treatments, and in the progressive decrease in Δ up the stem under drought. Differences in Δ between cultivars were consistent with differences in stomatal control of leaf water status following water stress. Values for Δ in tubers were consistently lower than in stem and leaf, and decreased more rapidly. Differences in Δ between cultivars did not reflect dry matter production in either treatment, and differences in water use were non-significant between cultivars under drought. So, plants can achieve similar dry matter production through different growth strategies when irrigated or droughted, and Δ does not provide a simple, indirect method of selecting for dry matter production under water stress. |
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Keywords: | Solanum tuberosum potato cultivar differences δ13C stable isotope water use efficiency water stress |
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