Effect of abscisic acid on the cytological components of the root growth

9 p.-3 fig.-3 tab.This paper reports the effect of abscisic acid (ABA) on the root growth in Allium cepa and the effects on the growth components, namely, cell flow and final cell size, and number of functional cells in each meristematic rib. With a continuous treatment by ABA steady state kinetics of growth is attained for each concentration, characterized by a constant growth rate. This growth is inhibited only by ABA 10-5M, 10-6M and 10-7M. The 10-7M concentration seems to act only on the cell size. At ABA 10-6M a slight decrease in the cell flow is also observed and at 10-5M the results suggest a decrease in the number of functional meristematic cells, in addition to the other two previously recorded effects. All these results are compared with those obtained by the same ABA concentrations in the short term experiment.This work was partially supported by a grant from "Fondo de Ayuda a la Investigación"(Spain 1968)Peer reviewe