Effect of High-Temperature Treatments on the Breaking of Dormancy in One-Year-Old Asparagus (Asparagus officinalis L.)

In the forced cultivation of asparagus (Asparagus officinalis L.), it is necessary to completely break the dormancy state. We investigated the effect of high temperatures on dormant asparagus (‘Welcome’) to develop an efficient method for the early breaking of dormancy. Dormant plants were treated at 20.0°C, 22.0°C, 24.0°C, 26.0°C, and 28.0°C for 21 d in incubators. After treatment, spear germination was observed in the plants treated at relatively high temperatures (26.0°C and 28.0°C), whereas those treated at 20.0°C, 22.0°C, and 24.0°C remained dormant. Dormant plants treated at 28.0°C for 2, 4, 8, 12, 15, and 20 d were moved to the greenhouse (average temperature 18.2°C) to evaluate the effects of the treatment period on dormancy breaking. Spear germination was observed in plants treated for 4, 8, 12, 15, and 20 d, while untreated plants and those treated for 2 d still appeared dormant. These results suggested that the dormancy of asparagus (‘Welcome’) could be broken by treatment for 4 d at 28°C.