Metabolism As a Function of Water Potential in Air-Dry Seeds of Charlock (Sinapis arvensis L.)

A new method is described for studying the metabolism of air-dry seeds. An initial pulse of (14)CO(2) was supplied to seeds maintained in air at controlled low water potentials for 6 months. Seeds were also infiltrated with 2-(14)C-acetate and with (14)C-l-leucine at 0 C, redried rapidly at 0 C, and maintained at controlled low water potentials for 4 to 6 weeks. The metabolism of the air-dry seeds was a function of the water content of the tissues, which was in equilibrium with the water potential at the seed surface. The fixation of (14)CO(2) and the utilization of 2-(14)C-acetate increased exponentially with water content. The incorporation of (14)C-l-leucine into protein increased linearly with water content. Metabolism was not reduced to a low rate except in air-dry seeds at the lowest water potentials (-1716 to -762 bars) with 4 to 6% water.