Abstract
Typically, asparagus dormancy is induced under 16°C. However, seedlings grown in unheated greenhouses are often subjected to night temperatures lower than 16°C. We investigated whether young asparagus has a developmental phase that prevents it from acquiring the ability to become dormant using three cultivars, Welcome, PA100, and Super Welcome. Sixteen different kinds of aged plant were used in each cultivar. The plants were incubated at 16 or 22°C for 12 days. Spear emergences were observed in plants of all ages of ‘Welcome’ and ‘PA100’ incubated at 22°C, suggesting that these plants were not in the dormant stage. Among the plants incubated at 16°C, spear emergences were observed only in those aged 85 days or less of the cultivars, ‘Welcome’ and ‘Super Welcome’, and in those aged 105 days or less of the cultivar ‘PA100’. These results suggest that young asparagus plants have a developmental phase that prevented them from acquiring the dormancy characteristic. Although most of the 185- and 195-day-old plants were not induced to undergo dormancy at 22°C in ‘Welcome’ and ‘PA100’, approx. 40% of the plants were induced in ‘Super Welcome’. Additionally, almost all of the 185- and 195-day-old plants were induced to undergo dormancy at 16°C in ‘Welcome’ and ‘Super Welcome’, whereas 20–30% of the plants were not induced in ‘PA100’. Thus, we suggest that the temperature for inducing dormancy varies among cultivars.
