Studies on Breeding Sweet Potato Varieyies Adapted to True Se ed Planting. : I.Flowering Habit, Seed-Seting and Adaptability of Natural Flowering Population to True Seed Planting

Abstract

To eliminate the usual plant bed costs and to mechanize planting, sweet potato varie-ties adapted to true seed planting (direct sowing of true seeds) is expected to produce. Thus the recurrent selection procedure was applied using natural flowering population, and. the appropriate breeding procedure for developing synthetic varieties was discussed in this paper. In experiment I, flowering habits of natural flowering population were observed under stick-training culture in which two vines per plant were trained along the supporting sticks picking the leaf axils, and also yielding treLits such as number of roots, root weight, root size and dry matter percentage were recorded under the ordinary trans planting culture. In experiment II, yielding traits of the strains selected for number of seeds in the open-pollination of experiment I were evaluated under the true seed planting culture and the strains with high root weight and high dry matter percentage were selected to make a first cycle synthetic variety. Moreover the individuals were selected from the polycross progeny of the selected strains to make the second cycle open-pollinated population.