Study on the effect of cold stress and Gibberellic acid (GA) on dormancy breaking of potato minituber

To study the effect of gibberellic acid and cold shock on dormancy breaking of potato minitubers Var. Agria, a factorial experiment based on completely randomized design with four replications was used. Studied factors included: 1. Gibberellic acid (1000 ppm and Control) and 2. Cold shock at 2°C (C1: no cold, C2: a week of cold, C3: two weeks of cold, C4: three consecutive weeks of cold, C5: three intermitant weeks of cold). Germination percentage, number of sprouts/minituber, length of sprouts,field establishment of minitubers and yield/unit area were studied. Results showed that GA significantly stimulated minitubers germination. In the case of 1000 ppm GA, the number of sprouts/minituber was the highest in all levels of cold shock, while in the absence of GA, cold shock significantly increased number of sprouts/minituber and this trait significantly reduced by prolonged cold period. GA significantly increased field establishment of minitubers. In the case of GA, number of produced tubers/unit area was not significantly different in cold shock levels while in the absence of GA, this trait significantly increased by prolonged cold shock.