Storage Organ Development in Radish (Raphanus sativus L.). 1. A Comparision of Development in Seedlings and Rooted Cuttings of Two Contrasting Varieties

Development was compared in two contrasting varieties of radishgrown in nutrient solution. Differences in shape of the long,tapering radish of Long White Icicle and the smaller, roundCherry Belle were associated with differences in the growthof the upper part of the tap root. Thickening was the resultof , cambial activity and transverse scctions through the upperroot showed differences in both cell number and a l l size.Long White Icicle contained more cells in the secondary xylemand phloem/secondary cortex than Cherry Belle, and the non-lignifiedxylem parenchyma cells were also larger in Icicle. The upperpart of the tap root also elongated in Icicle but not in CherryBelle, and this was entirely due to an increase in cell numberin the longitudinal plane. Removing the distal part of the root system had little effecton storage organ size unless most of the root system was removed.Adventitious roots on seedling and shoot-tip cuttings of bothvarieties were capable of thickening and the single root developingon shoot-tip cuttings of Cherry Belle achieved a diameter greaterthan that of the radicle of the intact plant. Rooted cotyledonsof Cherry Belle cxrasionally produced small storage organs. Raphanus sativus, radish storage organ, root thickening, cambial activity