Effects and Interaction of Pre-chilling History and Daylength on Successive Floral Formation in Everbearing and Non-everbearing Strawberry Cultivars

Abstract

1. Three experiments were conducted to determine the effects and interaction of pre-chilling history and daylength on successive floral formation in everbearing and non-everbearing strawberry cultivars. 2. The previously non-chilled plant material of five strawberry cultivars ; everbearer oRabunda', and non-everbearers oFukuba'Hokowase'Aiko' anKletter Erdbeere Hummi', were grown in the growth chamber at a constant 20°C under 16 hour (16-LD) or 8 hour (8-SD) daylength for 30 days. The floral formation oRabunda' Aiko' anKletter' was induced under 16-LD and 8-SD, whereas that oFukuba' anHokowase' was inhibited by 16-LD , and prmoted by 8-SD. 3. Plants oRabunda'Kletter' anHokowase' were stored at 1°C for 4.5 months till 5 April 1987, then transferred to growth chamber and grown at 20°C under 16-LD from 5 April to 18 June. Among these cultivars, only thèRabunda' of everbearer continually formed flower buds during this experiment. 4Rabunda' plants that had been stored at 1°C for 2 months till 29 January 1988 were grow at 20°C under 16-LD or 8-SD from 29 January to 29 March. At the end of photoperiodic treatment, the floral initiation of 16-LD plant had occured at an average of 2.2-node intervals in the terminal bud; 8-SD induced flower bud at an average of 3.6-node intervals in the terminal bud. 5. The above mentioned results indicated that the non-chilled plant oAiko' anKletter' showed the similar photoperiodic respon se to the non-chilled plant oRabunda'.