Influence of exogenous gibberellins inhibitors on tuber sprouting in yam

Abstract

To induce sprouting two gibberellin inhibitors, uniconazole-P (UP) and prohexadione-calcium (PC), were applied to foliage of white Guinea yam (Dioscorea rotundata) and water yam (D. alata) 30 days before harvest or to tubers at harvest. The tuber sprouting period was shortened by about 35 days in D. alata TDa 95/00328 in response to UP and PC, and TDa 92-2 in response to PC, but not in others through foliage treatment. Sprouting of tubers was promoted in D. rotundata TDr 99-12 and D. alata TDa 99/00049 and TDa 291 when they were soaked in UP or PC, but the others had a limited response at harvest. Sprouting of TDa 99/00049 tubers started 70 days earlier and the periods of sprouting were 35 to 42 days shorter in response to the UP and PC. Foliar application was more effective in promoting tuber sprouting than tuber soaking at harvest in TDa 92-2 and TDr 93-31, and the reverse was true for TDr 99-12 and TDa 291. The responses of yam varieties to UP and PC seem to vary depending on the stage of dormancy in their tubers.