ISHS Acta Horticulturae 886: X International Symposium on Flower Bulbs and Herbaceous Perennials
FORCING OF NEW CULTIVARS OF PAPERWHITE NARCISSUS FOR EARLY FLOWERING |
| Authors: | D. Cohen, D. Sandler Ziv, C. Fintea, A. Ion, A. Cohen, R. Kamenetsky |
| Keywords: | florogenesis, geophyte, ornamental bulb, temperature requirements |
| DOI: | 10.17660/ActaHortic.2011.886.59 |
| Abstract:
Paperwhite narcissus of the Tazetta group leads flower bulb production in Israel, with more than 20 million bulbs exported annually for dry sales and flower production. The recent release by ARO, The Volcani Center of the new cultivars ‘Ariel’, ‘Inbal’ and ‘Nir’, suitable for pot-plant production necessitate the development of methods for flowering manipulations. Under natural conditions in Israel, paperwhites flower in December-January. In order to advance flowering to October-November, three forcing strategies were applied to ‘Ariel’, ‘Inbal’ and the well-known cultivar ‘Ziva’. Following the determination of the stage of flower development on 1 July 2007, bulbs were kept in different storage regimes: (1) open shed, temperatures 18-22/25-30°C (night/day); (2) constant 25°C; (3) 25°C, following by 2 weeks at 13°C; (4) 25°C, following by 2 weeks at 9°C. Storage at 25°C accelerated intrabulb flower differentiation and shortened forcing time by 2 weeks in ‘Ziva’ and ‘Inbal’ and by 4 weeks in ‘Ariel’, in comparison with the open shed control. Storage at 9 and 13°C for 2 weeks prior to planting caused stalk elongation inside of the bulb. Bulbs were planted on 1 September in 15 cm pots, 3 bulbs/pot, and grown in the phytotron at 20/12°C (day/night) and 10 hours of natural sun light. In all cultivars, storage at 25°C followed by a short period at lower temperatures of 9 or 13°C resulted in the anthesis on 7-10 October, after 37-40 days of growth. Thus the time to anthesis was reduced by 16-18 days in comparison to the control. Storage at 25°C advanced anthesis by 9-10 days. In ‘Ariel’ and ‘Inbal’ lower storage temperatures significantly increased the number and diameter of individual flowers, while the opposite result was obtained for ‘Ziva’. Storage at 25°C significantly increased the number of flower stalks per bulb in ‘Inbal’, but in ‘Ziva’ the increased number of flower stalks was observed after storage in the open shed. We conclude that the physiological requirements for ‘Ariel’ and ‘Inbal’ are different from those of ‘Ziva’, and that a precise pre-planting protocol is needed for each cultivar. | |
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