delta 13C of leaf-respired CO2 reflects intrinsic water-use efficiency in barley

作者：Barbour Margaret M^*; Tcherkez Guillaume; Bickford Christopher P; Mauve Caroline; Lamothe Marlene; Sinton Sarah; Brown Hamish

来源：Plant, Cell and Environment, 2011, 34(5): 792-799.

DOI：10.1111/j.1365-3040.2011.02282.x

• Hordeum vulgare
• Triticum x Secale
• carbon isotopes
• fractionation
• photosynthesis
• transpiration
• water-use efficiency

Leaf intrinsic water-use efficiency (WUE), the ratio of photosynthetic rate to stomatal conductance (A/g(s)), is a key plant trait linking terrestrial carbon and water cycles. A rapid, integrative proxy for A/g(s) is of benefit to crop breeding programmes aiming to improve WUE, but also for ecologists interested in plant carbon-water balance in natural systems. We hypothesize that the carbon isotope composition of leaf-respired CO2 (delta 13C(Rl)), two hours after leaves are transferred to the dark, records photosynthetic carbon isotope discrimination and so provides a proxy for A/g(s). To test this hypothesis, delta 13C(Rl) was measured in four barley cultivars grown in the field at two levels of water availability and compared to leaf-level gas exchange (the ratio of leaf intercellular to ambient CO2 partial pressure, C-i/C-a, and A/g(s)). Leaf-respired CO2 was more 13C-depleted in plants grown at higher water availability, varied between days as environmental conditions changed, and was significantly different between cultivars. A strong relationship between delta 13C(Rl) and delta 13C of sucrose was observed. delta 13C(Rl) was converted into apparent photosynthetic discrimination (Delta 13C(Rl)) revealing strong relationships between Delta 13C(Rl) and C-i/C-a and A/g(s) during the vegetative stage of growth. We therefore conclude that delta 13C(Rl) may provide a rapid, integrative proxy for A/g(s) in barley.

• 出版日期2011-5