Accelerated and increased development of inflorescences in tomato plants from irradiated seeds

Mecheast-22 cultivar tomato seeds were irradiated with 250–1000 rad doses of ⁶⁰Co gamma rays and the germinated seedlings transplanted to individual pots and grown in a greenhouse. The number of flower clusters, buds and open flowers were scored at 25, 45, 70 and 90 days after transplanting. Radiation caused earlier and increased flower cluster formation, possibly by stimulating a still unknown mechanism which initiates the change from vegetative to generative growth. At D45, all doses increased the number of flower clusters, 500 and 750 rads giving significant increases. This increase was maintained throughout the experiment. Most of the extra clusters were located along the side stems. All radiation treatments gave significantly more open flowers at the beginning of the flowering period. The 500 and 750 rad doses significantly increased the number of buds at 45 days, and of open flowers at 70 days after transplanting, the latter amounting to 6–6·5 extra flowers per plant. The mean number of flower buds or flowers per cluster and the percentage of clusters without flowers were not affected by radiation. The radiation treatments did not significantly affect the vegetative development of the plants, although there was a slight trend towards increased “tillering” at 500–1000 rads.