Compensation Points and Carbon Dioxide Enrichment for Lettuce Grown Under Glass in Winter

Abstract

Measurements of Γ, the minimum intercellular-space carbon dioxide concentration or carbon dioxide compensation point, made at two temperatures and at light intensities from 15 to 1,500 f.c., were used to study the relation between the compensation points for light and carbon dioxide. This was found to be hyperbolic and consistent with the Warburg–Maskell model for photosynthesis. The apparently beneficial effects of carbon dioxide enrichment of the atmosphere at increased temperature, found in practice with lettuce or other crops grown under glass at light intensities that might be expected to be severely limiting, must be in part due to the reduction of the light compensation point at high carbon dioxide concentration.