Ethephon Promotes Sprouting and Increases Vigor in Yam Seed‐Tubers

The yam ( Dioscorea alata L.) is of social and economic relevance for small farmers in Northeast Brazil, but its cultivation is hindered by the low quality of propagative material and a long dormancy period exceeding 90 days. This study evaluated the effect of Ethephon doses and different tuber segments of the São Tomé variety on sprouting and seedling vigor. A 4 × 4 factorial design was used with four Ethephon concentrations (0, 30, 60, and 90 mL·10 L −1 ) and four tuber parts (whole, head, middle, and tip). Ethephon at 90 mL·10 L −1 advanced sprouting by 15 days. At 30 mL·10 L −1 , it increased sprout number by 3.12 times, leaf number by 8.2 times, and shoot dry mass by 6.8 times compared to the control. Whole tubers showed the lowest vigor. A negative correlation was observed between sprouting time and most growth parameters. Cluster analysis formed five vigor‐based groups, with highest vigor in treated segments. The application of 30 mL·10 L −1 Ethephon to base, middle, or tip segments is recommended to promote earlier sprouting and enhance seedling vigor.