EFFECT OF X-IRRADIATION UPON GROWTH AND REPRODUCTION OF TOMATO

Materials and methods Seven different sets of experiments (series I-VII) were carried on, in most of which the John Baer variety of tomato was used. In the first three series irradiation was carried out when the plants were from 1 to 3 centimeters in height; in the fourth, three medium doses were given at two-week intervals,-at a time when the plants seemed to be recovering from the effects of the previous dose. In the last three groups, the plants were not exposed until small buds had formed. The general procedure was to plant seeds in 5-inch pots in the greenhouse. The plants of the first three series were irradiated before the true foliage leaves had developed. Soon afterwards these seedlings and an equal number of controls were transplanted to larger pots where they grew to maturity. Plants of series V, VI, and VII were transplanted at an early+ age but were not irradiated until small buds had formed. Irradiations of the first five groups were made with a Victor X-ray machine with the following "set-up": 5-inch spark gap, 5 milliamperes current, no filter, distance30 cm., time from 20 to 30 minutes. For the last group, an Acme machine was used with the potential 90 K.V., 5nmilliamperes current, no filter, distance 30 cm., time 20 minutes.