[Studies on compensation in medicinal plants. Compensative effects in leaves of Papaver somniferum L. on photosynthetic and transpiration rates].

Abstract

To investigate compensative effects in leaves of Papaver somniferum L., the relation between photosynthetic rate and light density and leaf temperature, and the influences on photosynthetic and transpiration rates of removal of the three upper leaves were examined under field conditions. The light saturation point in leaves of P. somniferum was about 900 micro molm-2sec-1 and the photosynthetic rate at the light saturation point was about 13.5 micro molm-2sec-1 between 23 and 28 degrees C in leaf temperature. The light compensation point in leaves was nearly 50 micro molm-2sec-1. The influence of leaf temperature on photosynthetic rate was significant, so that the latter showed a remarkable decrease when the leaf temperature was above 30 degrees C. When the three upper leaves were removed, the photosynthetic and transpiration rates in the 4th leaf tended to increase as compared with control level, although the increases were not significant.