EARLY PLANT-GROWTH AND YIELD OF SWEET-POTATO GROWN FROM SEED, VEGETATIVE CUTTINGS, AND SOMATIC EMBRYOS

Early plant growth, root quality, and yield from sweetpotato plants ob tained from zygotic seed, somatic embryos, or cloned from stock plants (through micropropagation, rooted node explants, or nonrooted termina l vine cuttings) were compared in field plantings established in 1986, 1987, and 1988 in Gainesville and/or Homestead, Fla. At planting, tra nsplants derived from somatic embryos had more nodes than the other pr opagules, while vine length per plant was greatest with nonrooted vine cuttings obtained from stock plants. The number of nodes (up to 253%) and vine growth (up to 517%) were greater when plants were derived fr om stock plants and zygotic embryos than from somatic embryos 4 weeks (1987) and 6 weeks (1988) after planting. Vegetative growth, larger-si zed storage roots (>6 cm in diameter), and total yields (all root grad es combined) were consistently. reduced when plants were derived from somatic embryos compared with propagules of stock plant origin. Plants obtained from somatic embryos required more time for roots to bulk or size than the other propagule types. Root yield from plantlets derive d from somatic embryos showed a 14-fold increase when harvest was dela yed at least 53 more days. Root weight, regardless of harvest date, wa s greater when plants were derived from stock plants rather than from somatic embryos, while in most cases plants derived from somatic embry os yielded a greater number of roots than from stock plants. Plants ob tained through somatic embryony and harvested at a later date typicall y had yields exceed 1.8 kg per plant. Morphology of plants obtained fr om somatic embryos was uniform and identical to plants derived from st ock plants.