EFFECTS OF HARVEST DATE ON CERTAIN CHEMICAL AND PHYSICAL CHARACTERISTICS OF SWEET-POTATO GROWN IN SOUTHWESTERN ONTARIO

Effects of harvest date on yield, concentration of selected minerals a nd carbohydrates of two sweet potato cultivars (Ipomoea batatas Lam.) grown in Southwestern Ontario, Canada were measured over 3 yr. Harvest date for maximum yield of table grade roots was found to be mid to la te September. Mineral concentrations were not consistently affected by dates of harvest. The concentration of Na in the roots was found to b e lower than values reported for other production regions for both cul tivars. In 2 of 3 yr, sucrose and total sugars increased and starch, p ercent dry weight and root growth rate decreased as harvest date was d elayed from 27 September to 11 October. These effects of delayed harve st date were attributed to low temperatures late in the normal harvest time period for this production area.