Abstract
The tuberization responses of four sweet potato cultivars to shade during the first eight weeks of growth were compared. Tuber fresh weight was not affected in 25% shade, but in 55% shade values were noticeably lower, and in 73% shade tuberization was almost completely suppressed in all cultivars. The responses resulted from slower tuber growth in 55% shade and from delayed tuber initiation and slower tuber growth in 73% shade. The major cultivar differences observed were that two cultivars had fewer thick roots, lower potential and percentage tuberization indices and fewer and smaller tubers in 55 and 73% shade than the other two; the latter demonstrated greater capacity for tuber initiation and tuber growth even in 73% shade and thus appeared to be more shade-tolerant than the former in early growth.
