Effects of Chilling History on Successive Flowering and Runner Development of Everbearing and Non-everbearing Strawberry Cultivars

Abstract

The purpose of this paper is to compare the effect of chilling history on successive flowering, runner development and petiol elongation among everbearing cultivars, Rabunda, Ostara and Kletter-Erdbeere Hummi (Kletter), and June-bearing cultivar, Hokowase, of strawberry. Materials were separated into four groups. The first three groups were left outdoors until November 15, December 15, 1986 and January 15, 1987, respectively. The remaining group was stored at 1°C from November 6 to January 15. After these treatments, plants were transferred to a greenhouse that was controlled at a minimum night temperature of 10°C and a maximum day temperature of 30°C, under a 16h day photoperiod. Number of inflorescences and runners as well as length of petiol were measured from February 19 to June 24, 1987.
1. All the plants of ‘Rabunda’ and ‘Ostara’ successively formed inflorescences as did cultivars of ‘Hokowase’ and ‘Kletter’ that were transferred to the greenhouse by December 15. On the other hand, flowering of ‘Hokowase’ and ‘Kletter’ that were transferred to the greenhouse on January 15 was inhibited.
2. Runner production was noted in neither ‘Rabunda’ nor ‘Ostara’. But chilling promoted runner production in ‘Hokowase’ and ‘Kletter’.
3. ‘Hokowase’ and ‘Kletter’ showed much more sensitivity to chilling in petiol elongation than ‘Rabunda’ or ‘Ostara’.
4. These results indicate that ‘Rabunda’ and ‘Ostara’ are less sensitive to chilling than ‘Hokowase’ and ‘Kletter’. Although ‘Kletter’ has been considered to be an everbearer, it showed an intermediate response between everbearer and June-bearer. Therefore, it may be concluded that the flower bud initiation of everbearers (‘Rabunda’ and ‘Ostara’) is little affected by chilling history and they can initiate the flower bud even under long day photoperiods from spring to summer.