Cell and Axis Elongation in Etiolated Soybean Seedlings are Altered by Moisture Stress

Elongation of etiolated soybean hypocotyls was reduced by moisture deficiency. The maximum cortical cell length below the meristem was less in stressed seedlings than in unstressed seedlings. Reticulate xylem elements were closer to the top of stressed seedlings, and the region of hypocotyl elongation was smaller in stressed seedlings than in unstressed seedlings. Therefore, soybean seedlings had a typical response to the slowing of growth by stress, in that the maturation of cells occurred closer to the meristem. Elongation of cells per unit of displacement along the axis, within the region of elongation, was not reduced by stress, but the hypothesis that homeostasis maintains maximum cell length in soybean hypocotyls under stress is contradicted by these observations.