Aluminium and ammonium ion effects on the depletion of potassium from hydroponic solutions byTrifolium repensL. cv. ‘grasslands hoia’

Abstract

The uptake of potassium from hydroponic solutions by Trifolium repens is reduced in the presence of NH 4 + . However, it appears that a concurrent effect of NH 4 + is to induce, via the plant, marked changes in pH which counters the effect of NH 4 + on K uptake. When the variation in measured mean K concentration changes (KCC) associated with the variation in pH change is removed by analysis of the data using pH as a covariate, an apparent increase in K removal from solution is observed in the presence of NH 4 + . Plant-induced changes in pH also apparently affect the Al-NH 4 + interaction. This treatment combination induces a plant effect on the pH which in turn keeps the KCC at a fairly constant level resulting in no apparent interaction. However covariate analysis reveals the marked effect Al has on K uptake at the zero NH 4 + level. Al in the nutrient media at 148 uM causes an apparent K efflux which can not be 1635