The effects of different levels (24, 48, 72hr.) of preheating (30℃) and soil moisture (80∼90%) on the sprouting of the whole and cut pieces of sweet potato (Ipomoea batatas) roots were investigated. The results obtained were as follows;
1. In the old roots, heating and soil moisture treatments for 48hr. gave the greatest increase in the number of sprouts and could break the proximal dominance, while in the number of leaves and the length of sprouts, the treatments for 72hr. were highest.
2. In the new roots, the sprout stimulating effects of heating and soil moisture was greatest in the treatments for 72hr., but it was less than that of the effect of breaking proximal dominance.
3. In pieces of the roots, the treated ones produced more and earlier sprouts than the nontreated. Each part pieces treated for 72hr. showed a significant increase in sprout growth.
4. In electrophoretic band patterns of general soluble protein and esterase, differences between the treated and the nontreated roots were observed mostly in the upper part of root (the proximal end), whereas there was no difference in the lower part of root (the distal end).
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