Cadmium Influence on Respiratory Gas Exchange of Pinus resinosa Pollen

Release of CO₂ and uptake of O₂ by Pinus resinosa Ait. pollen treated with 0, 0.004, 0.045, or 0.450 mM Cd²⁺ were determined manometrically. Respiration after 1.5 h was stimulated in the 0.450 mM treatment, but declined sharply after 3.5 h. CO₂ evolution was inhibited more than O₂ uptake. Pretreatment with Cd²⁺ inhibited aflization of exogenous sucrose, and conversely, exogenous sucrose did not overcome Cd²⁺ effects on gas exchange. Cd²⁺ did not act as a classical uncoupler of oxidative phosphorylation. There was no correlation of pollen germination and germ tube elongation with Cd²⁺ effects on gas exchange.