Oxygen Consumption of Lettuce Seed in Relation to Photocontrol of Germination

Abstract

1. Seeds of lettuce variety Grand Rapids vary with duration of imbibition in their sensitivity to promotion of germination by red radiation and inhibition of germination by infrared radiation, the changes being opposite for the two effects after about 12 and 20 hours of imbibition at 20^⚬ C. 2. Respiration changes in nongerminating seed of lettuce varieties Big Boston and Slobolt that are correlated with these changes in sensitivity to radiation also occur. 3. Respiration of the nongerminating seed is constant during the periods between the changes in sensitivity to radiation. 4. The relation of these phenomena to the photoreaction controlling seed germination is discussed in terms of limiting factors.