The Effect of Radium on the Growth of Plants

Abstract

A MONG the many remarkable properties of radium it was perhaps natural to expect that it might have some definite effect on plants, and even, under suitable conditions, cause sufficient increase in the amount of growth to justify its use in horticulture and agriculture. The early observations of Dixon and Wigham1 at Dublin, however, did not seem very promising: 100 seeds of cress (Lepidium sativum) were uniformly distributed over an even surface of moist quartz sand, and after germination had taken place a sealed tube containing 5 mgms. of radium bromide was set 1 cm. above the central seed. The seedlings grew up, but without any curvature indicating positive or negative “radiotropism,” and the only noticeable effect was a slight depression of growth in those within i cm. radius of the tube. As stronger preparations of radium became available more definite retardations and inhibitions were observed: thus Gager, in an elaborate report,2 noted a more or less complete inhibition in cell activities in younger and especially embryonic tissues, with few exceptions. The action of radium through the soil, however, was different; germination and growth were both accelerated, and the plants furthest away were stimulated most. Acqua3 found that different plants, and even different organs of the same plant, were differently affected, the root system in general responding more markedly than the aerial parts, and in his experiments being arrested in their development.