Effects of Ethephon Applications and Cold Storage of Cuttings on Growth and Flowering of Summer-to-Autumn-Flowering Chrysanthemums under Open Field Conditions

The effects of multiple sprayings of ethephon and cold storage of cuttings on stem length and flowering of summer-to-autumn-flowering large-flowered chrysanthemum (Dendranthema grandiflorum (Ramat.) Kitamura), were studied to obtain cut flowers with 80 cm stem length in September under open field conditions in both lowland and highland environments. In both cultivars, a combination of ethephon sprays, lighting and cold storage of cuttings had an additive effect on stem length. In ‘Summer-yellow’, flowering was inhibited by four applications of ethephon spray and 30-day cold storage of cuttings on 19th September and the stem length was 90.9 cm in the lowlands. In the highlands, stems of ‘Seiun’ and ‘Summer-yellow’ were longer than in the lowlands when 45-day cold storage of cuttings and ethephon sprays were used. In ‘Summer-yellow’ flowering was inhibited by four applications of ethephon spray and 45-day cold storage of cuttings on 28th September. The stem length was 80.1 cm in the highlands. It is possible to harvest high quality flowers of summer-to-autumn-flowering chrysanthemum with stem lengths of more than 80 cm in late September after ethephon applications and cold storage of cuttings under open field conditions.