Linking light capture with CO_2 fixation: new methods enable integration from the chloroplast to the leaf

摘要

There is a large amount of literature published on the photosynthetic properties of intact leaves obtained from gas exchange measurements. Often data are interpreted by applying the C_3 biochemical model of Farquhar, Von Caemmerer & Berry (1980). This model scales from the biochemistry of a chloroplast to that of a leaf by assuming that the photosynthetic capacity of any chloroplast in a leaf is directly proportional to the light absorbed by that chloroplast. It is well known that the properties ofchloroplasts differ through a leaf (Terashima & Inoue, 1984, 1985a, b). It has also been shown that light is attenuated through a leaf either by direct measurement of reflected and transmitted light from paradermally sectioned leaves (Terashima & Saeki,1983), or calculated from light measured by optical fibres inserted through leaves (Cui, Vogelmann & Smith, 1991, Vogelmann & Bjorn, 1984, Vogelmann, Bornman & Josserand, 1989, Vogelmann et al., 1988). However, until recently, it has not been possible to rigorously examine the assumption that photosynthetic capacity per unitabsorbed light is a constant.