The Photosynthetic Activity of the Wheat Ear

Abstract

The contribution made by ear photosynthesis to grain yield was found to vary from 10 per cent to 44 per cent depending on the technique used, and on environmental conditions. A modified ear-shading technique is described which overcomes some of the undesirable features of previous ear-shading methods. It was also found that ear photosynthesis comprises two processes, (a) the assimilation of atmospheric CO2 and (b) the photosynthetic refixation of the ear's respiratory CO2. Dry-weight data and measurements of CO2 exchange both indicated that this latter component can make a significant contribution to grain yield.