Morphological and Anatomical Effects of Benefin Vapors on Tobacco (Nicotiana tabacum)

Abstract

In tobacco (Nicotiana tabacumL. 'Speight G-28′) exposed to benefin (N-butyl-N-ethyl-α,α,α-trifluoro-2,6-dinitro-p-toluidine) vapors from treated soil, the leaves formed after treatment were shortened, narrowed, distorted in shape, and had an abnormal vein pattern. The leaves that had developed before treatment did not have these symptoms. More leaves developed on treated than on untreated plants. The height of treated plants was reduced and many axillary buds became active prematurely. The injured leaves, in general, had fewer epidermal cells, stomata, and trichomes per unit surface area; a smaller volume of intercellular space; and were thicker than those of untreated plants. Many of the meristematic cells in the leaf primordia and shoot apex of treated plants contained large and distorted nuclei and were oriented in improper planes. The plate meristems established by activity of the marginal meristems gave rise to a mass of undifferentiating parenchyma cells in the mesophyll of the young leaves. There was little formation of the palisade or spongy mesophyll layers, but enlargement of the undifferentiating cells caused a radial expansion of the lamina.