SUSCEPTIBILITY OF SEVENTY SPECIES OF FLOWERING PLANTS TO X-RADIATION

Abstract

A 10-yrs.[image] study of the morphological effects of x-rays on the above-ground parts of 70 species of flowering plants resulted in the following grouping according to ray-susceptibility 15 species apparently unaffected by the rays; 15 slightly affected, particularly during their early growth stages; the remaining 40 species noticeably affected. Seedlings were irradiated with medium doses when the cotyledons were expanded and the growing tips were visible. Members of Chenopodiaceae, Umbelliferae, and Brassicaceae often gave indications of injury soon after treatment but by the time maturity was reached, manifested little effect. Plants noticeably injured by radiation were marked by decrease in total height; increased branching as in the Caryophyllaceae and Onagraceae; frequent occurrence of dichotomous branching, particularly in the Carduaceae; irregularities in shape, margins, and chlorophyll development of the leaves; delayed and reduced blossoming. Members of the Solanaceae, Scrophularia-ceae, and Carduaceae proved to be noticeably ray-susceptible, as were also the following genera in other families: Abronia, Ricinus, Lavatera, Ipomoea, Cobaea, Linaria, Thunbergia, Campanula, and Centranthus.