Effect of Previous Chilling, Day Length and Cold Storage on Runnering Habit in Everbearing Strawberry Cultivars ‘Natsuakari’ and ‘Dekoruju’

Abstract

We assessed runner production in everbearing strawberry cultivars (Fragaria × ananassa Duch.) 'Natsuakari' and 'Dekoruju', which exhibit poor ability to produce runners, thus limiting their propagation and use. Both cultivars required 1,000 h of chilling (< 5°C) to induce runner production when grown under a long day length (LD); however, they required longer chilling under a short day length (SD). Plants chilled for 2,000 h tended to produce more runners under SD than under LD. During spring and summer, the overwintered 'Natsuakari' plants produced the fewest runners under SD. In contrast, the overwintered 'Dekoruju' plants produced the fewest runners under LD. Thus, a longer day length did not always enhance runner production in these cultivars. In autumn, 90-day cold storage at -2°C was substituted for natural chilling for plants that were rooted in summer. For both cultivars, the production of runners by plants that were rooted in July was similar to or greater than that by plants that were rooted in May. The rooting of mother plants in July, which are more available than plants rooted in May, did not have a detrimental effect on runner production during the next early summer period. Considering total runner production till July, we concluded that it is appropriate to initiate cold storage in December for the 'Natsuakari' cultivar and in November or December for the 'Dekoruju' cultivar.

Confirmation of Everbearing Mutants in the Everbearing Strawberry Cultivar ‘Natsuakari’ and the Effect of an Overwintering Condition on Inflorescence and Runner Development

“…3). Consequently, the plants overwintered in the heated glasshouse did not satisfy the level of chilling required to break dormancy, > 1000 h (Hamano et al, 2011). It is well known that June-bearing cultivars have a continuous flowering pattern if chilling is avoided (Guttridge and Anderson, 1976;Voth and Bringhurst, 1958;Yanagi and Oda, 1992).…”

Recent Progress of Strawberry Year-round Production Technology in Japan

“…In addition, everbearers sometimes develop excessive branch crowns, inflorescences, and flowers, meaning more management and labor is required for debudding, pruning, and thinning. Some recent noteworthy work includes studies on the photoperiodic response of flowering under high temperature regimes 15,16,18 , flower induction by long-day treatment 9 , the high temperature effects on flowering and fertilization 3,4 , the involvement of chilling and runner production 7,8 , seasonal changes in fruit sugar content 5 , the analysis of root structure 30 , and the application to forcing culture 10 . Despite the shortage of information on flowering physiology, there are many active breeding programs involving new everbearing varieties in public and private institutions.…”