Differences in ion uptake among roots of various types

Ion uptake by tap and by lateral roots of peas (Pisum sativum L.) was investigated. The roots were either of intact seedlings or of seedlings whose young shoots or cotyledons had been removed. Tap roots seem to before responsive to temperature, and more susceptible to ion competition, than lateral roots. This indicates that the contribution of the metabolic uptake system, in tap roots, is dominant over that of the non-metabolic one. The uptake capability of both types of roots was lowered by removal of the shoots. Apparently, under such treatments, the contribution of the metabolic component, to the total uptake, was reduced. Studies of plant mineral nutrition should take into account such differences in the physiological and morphological characteristics that exist among the various root types.