Photoinhibition of Photosynthesis in a Winter Wheat Crop

Abstract

It is well established that exposure of many plants to low temperatures and high light can cause photoinhibition of photosynthesis (1), and recently this phenomenon has been demonstrated for maize leaves in the field (2). Maize is a chilling sensitive species and would be expected to experience photoinhibition at low temperatures in high light. However, it has not been ascertained whether chill-induced photoinhibition occurs in cold tolerant crops in the field. Photoinhibition of photosynthesis has been shown to result in a decrease in quantum yield of oxygen evolution (3) and a quenching of chlorophyll fluorescence (4), consequently these parameters can be used as useful probes of photoinhibition in leaf tissue. In this study measurements of the quantum yield of oxygen evolution and chlorophyll fluorescence were made on leaves of a wheat crop during the winter to evaluate whether photoinhibitory damage to photosynthesis occurred under field climatic conditions.