The Release of CO2 from Tall Fescue Leaves Following Photosynthesis under Photorespiratory and Non-Photorespiratory Conditions

Abstract

The two main transient phenomena in the course of CO2 evolution can be recorded when leaf of C, plant photosynthesizing in air is suddenly darkened. The first represents the postillumination burst of CO2 (PIB), a phenomenon originally described by Decker (1) from that the existence of photorespiration was first deduced. After that follows a period of increased respiration, a phenomenon termed light-enhanced dark respiration (LEDR) (2). Generally similar sensitivity of PIB and enhanced respiration to oxygen observed in tall fescue leaves (3) suggests the contribution of photorespiratory substrates. However, the solution of bicarbonate introduced into these leaves greatly enhanced both phenomena under photorespiratory conditions. The promotion of LEDR by bicarbonate have also been observed in mesophyll protoplasts of pea (4). Information on the effect of temperature on the transient CO2 exchange phenomena under various O2 concentrations is limited. Only the response of PIB to temperature at 21% O2 has been studied (5). The purpose of the present study was to examine of how a temperature affects PIB and enhanced respiration in tall fescue leaves under photorespiratory (21 and 50% O2) and non-photorespiratory (1% O2) conditions.