Effects of High Temperature Treatment on the Sprouting and Elongation Rate of Asparagus Spears

In this study, we investigated the effect of high temperature on spear sprouting and elongation in asparagus to explore new approaches to control the harvest period in asparagus production. Four-year-old rootstocks of ‘UC157’ were grown in chambers in the dark at 30°C (30°C treatment), 34°C (34°C treatment), 38°C (38°C treatment), and 42°C (42°C treatment) for 14 days, and then at 25°C for 18 days. In the 42°C treatment, no spear sprouting was detected, and all rootstocks died. During the high temperature period, the number of sprouted spears was significantly lower in the 38°C treatment than in the 30°C treatment, whereas after the high temperature periods, the number was significantly higher in the 38°C treatment than in the 30°C and 34°C treatments. The total number of sprouted spears during and after the high temperature periods was not significantly different between the 30°C, 34°C, and 38°C treatments. The elongation rate of the spears during the high temperature period was significantly lower in the 38°C treatment than in the 30°C and 34°C treatments, whereas there were no significant differences in the mean spear elongation rate after the three high temperature treatments. These results suggest that a temperature of 38°C can be used to control spear sprouting reversibly by its application and cancellation.