The effect of paclobutrazol on the growth and uptake of Ca and K by apple seedlings 1

Abstract

Addition of paclobutrazol (PP333) at 0.2 ppm to a nutrient solution in which 11‐month‐old apple seedlings were growing reduced terminal growth, fresh weight increase (FWI), transpiration and Ca and K uptake per seedling. Total root surface area was not affected by PP333 treatment. Reduced Ca uptake preceded the reduction in transpiration and FWI. In the case of K these changes were parallel. This may indicate that different mechanisms were responsible for reduced Ca and K uptake in PP333‐treated plants. At the conclusion of the experiment control and treated plants were absorbing similar amounts of Ca per unit of FWI. At the same time the amount of K uptake per unit of FWI was significantly lower in treated than control plants.