Establishment of cultivation method for short stem standard chrysanthemum four times a year by the combination of autumn flowering cultivar 'Zinba' and summer-autumn flowering cultivar 'Iwanohakusen'

This study was carried out to establish 4 times a year cultivation of short stem standard chrysanthemum by the combination of autumn flowering cultivar 'Zinba' and summer-autumn flowering cultivar 'Iwanohakusen' The results obtained were as follows: l. When the cultivar 'Zinba' was planted in October and subjected to the short-day treatment 3 weeks after planting, the flowers with 60 cm long stems could be harvested from 80 days after planting. When the same cultivar was planted in December with the short-day treatment 3 weeks after planting, the flowers of the same plant form were harvested from 90 days after planting. When this cultivar was planted in April with short-day treatment 2 weeks after planting, the flowers of the same quality were harvested from 65 days after planting. When the cultivar 'Iwanohakusen' was planted in June with the short-day treatment 4 weeks after planting, flowers with 60 cm long stems could be harvested from 70 days after planting. Thus, we could successfully grow standard chrysanthemum with short stem (60 cm) 4 times a year in the same field. 2. The flowers of high market quality were produced when three plants were grown in a hole on both sides of the flower net with three holes 15, 22 and 15 cm crosswise and 15 cm lengthwise. When four plants were grown in a hole, however, the flower quality significantly declined because of the high plant density. 3. In the cultivar 'Zinba', which was planted in December and harvested in March, the flowering time delayed two weeks when cuttings were taken from mother plants grown in plastic house without heating in winter. The delay was not observed with mother plants grown at 15 deg C, or higher.