effect of salinity on growth of Phaseolus vulgaris L.. I. Anatomical changes in the first trifoliate leaf

When plants of Phaseolus vulgaris were grown in culture solution containing 48 m mol 1⁻¹ sodium chloride, the first trifoliate leaves were always smaller in area than those of control plants. The leaves of the salttreated plants however could become thicker. This increase in thickness was brought about by the increase in the thickness of the spongy parenchyma layer. The palisade parenchyma layer was always thinner than that in the control leaves. While these latter leaves expanded predominantly by cell division, this only held for the early stages of expansion of the leaves of salt-treated plants. In this case cell division ceased when the leaves were about half their maximal size and further increase in area was brought about by an increase in volume of the spongy parenchyma cells.