Some Effects of Ultra‐violet Radiation on Leaves of French Bean (Phaseolus Vulgaris L.)

Exposing the primary leaves of French bean to ultra‐violet light produces a variety of effects, their magnitude depending on the extent of the exposure and the subsequent treatment of the leaves. Effects include some that are externally obvious, such as glazing and bronzing; others are detectable by changes in susceptibility to virus infection, by increased sensitivity to damage by ultra‐violet, and by an increased tendency for cells to collapse when the leaves are kept in darkness. Some of the effects can be counteracted by exposing leaves to visible light. Effects of radiation are not confined to epidermal cells, and measurements with detached epidermis indicate that from a quarter to a half of incident radiation of wave‐length 2536 A. may be transmitted by the epidermis.