Analysis of the Effect of Cool-treatment on Mature Leaves

Abstract

Most plants change their leaf characteristics, depending on growth temperatures. Recent studies showed acclimation of leaves is affected not only by their local environment but also by the environment of lower mature leaves. Araya et al. (2007) suggested that the photosynthesis of the young leaves is affected by the redox state of the mature leaves. Thus, it is possible that temperature acclimation of young leaves is also affected by the temperature of mature leaves. In this study, we examined effects of temperature of a mature leaf on development of young leaves in Helianthus annuus. When only the mature leaf was treated with air at 16 ºC, the palisade layer of the young leaves became thicker, and photosynthetic rates of the young leaves were higher than those of the control plants. These results suggested that the temperature of the mature leaves affects both morphologic and photosynthetic properties of the young leaves.