Abstract
Any visible injury can not be observed when the whole rice seedlings (Akitakomachi) are exposed to chilling conditions around 10°C, except the leaf-rolling, likely a result of water deficit caused by root inactivation. We, however, observed the severe injury that often led to leaf death after such treatments, only when the roots were not exposed to low temperature. We compared chlorophyll fluorescence parameters, in order to help define the mechanism of this chilling injury. The rice seedlings of the 3rd leaf stage were treated in low air and high root temperature (10°C/25°C) with the 12h-light (650 µmol·m-2·s-1) and 12h-dark period. A big change occurred between the first and second light period. This led to a big and rapid decrease in the photosynthetic capacity. The mechanism of this chilling injury is discussed in terms of the function of photosynthesis, water supply from roots and visible injury.
