Abstract
The growth of the pod and the number of seed on in vitro cultured pea (Pisum sativum L. var. Kinusaya) were examined. When the pod or immature seed born in vitro was cultured, the effect of the developmental stage of the explants on the period for alternation of generation was investigated. Combining the data, a way of accelerating generation turn-over in vitro and the use in practical breeding were considered. The results obtained are ; 1. Pea cultivars produced 2.0-2.4 seeds per plant in vitro. 2. The enlargement and ripening of seed in vitro were advanced at 25°C than were those at 20°C. 3. When 25-day old pods or 30-day old seeds after anthesis were picked and re-cultured in vitro, the alternation of generation of the pea was completed in 82 days. 4. The plants set many pods in vitro, when the previous pod was removed at an early developmental stage. 5. The seed ripened in vitro could be sowed in the field without acclimation. These results indicate that by accelerating the generation turn-over by in vitro pod culture, the breeding period of the pea can be shortened.
