Sprouting induction in yam tubers (Dioscorea rotundata Poir) with the application of growth regulators

Abstract

Natural dormancy of yam tubers can last several months, which makes storage mandatory in this crop before starting a new planting. This situation implies additional risks and costs for the farmers, which sometimes a forced to sow using tubers that have not yet completed their natural dormancy period. Consequently, irregular sprouting and uneven crops occur in the field. Therefore, the objective of this research was to evaluate the effect of applying plant growth regulators (PGR), such as thiourea, mepiquat chloride and ethephon on the induction of early sprouting of yam tubers in two varieties (cv. 0307‑49SB and 0307-50CB), harvested at 149, 179, 269 and 326 days after sowing (DAS). The results showed that growth regulators influence sprouting in tubers harvested at 179, 269, and 326 DAS, ethephon (1 g L‑1), being more effective in tubers of 179 DAS, thiourea (10-20 g L-1), those of 269 DAS, and mepiquat chloride (1-2 g L-1), in tubers of 326 DAS with similar effects on the two yam varieties. No effects of growth regulators were observed on sprouting in tubers of 149 DAS, which was attributed to immaturity of developing tissues. The study concludes that the application of growth regulators may induce early sprouting of yam tubers.