Effect of Potassium Deficiency upon Translocation of 14C in Detached Blades of Sugarcane

Abstract

The translocation of radioactive photosynthate was studied in blades detached from plants which had been grown in nutrient solution with and without potassium. Basipetal translocation decreased in the blades of plants deprived of potassium, even when deficiency symptoms were not visible. In such slightly potassium-deficient leaves, translocation was decreased in the light but not in the dark. More severe potassium deficiency decreased translocation both in darkness and in light. Potassium deficiency decreased translocation at light intensities giving no difference in rate of photosynthesis between plus and minus potassium leaves and even at light intensities at which there was no net fixation of carbon dioxide. At all levels of deficiency, the relative decrease in translocation was greater than the relative decrease in photosynthesis. Translocation was affected at potassium deficiency levels which had no effect upon photosynthesis. Potassium deficiency decreased translocation relatively more than it decreased moisture content. There was a much better correlation between the decrease in potassium and translocation than between the decrease in moisture and translocation. An experiment with radioactive phosphorus indicated an upset in phosphorylation in the stems of potassium-deficient plants.