Stimulation of Rooting by Exposing Cuttings of Runner Plants to Low Temperatures to Allow the Raising of Strawberry Seedlings during Summer

Abstract

The effect of exposing runner plants cut from strawberry (Fragaria × ananassa Duch. ‘Tochiotome’) to low temperature to stimulate rooting was examined for its usefulness as a practical strategy for raising seedlings from cuttings taken from runner plants dropping in the air to force elevated bed strawberry culture during the summer. The rooting of cuttings cultured at various temperatures for 7 days was good at 15°C to 25°C but was reduced at 5°C and 30°C; however, cuttings excised from ten different cultivars showed varying responses for the most suitable temperature for rooting. The rooting of cuttings from ‘Tochiotome’ cultured at 30°C for 5 days after pretreatment at 5°C for 2 days was almost the same as for cuttings cultured at a constant 15°C for 7 days, but rooting of cuttings cultured at 30°C for 7 days was retarded. Interestingly, rooting was observed by storing only the crown at 5°C for 2 days even if both foliage and shoot tip were detached. Rooting was better in dark conditions than with 16-h day length, and was best for the subsequent development stage of runner plants with 2.5 leaves attached. Our results showed that rooting occurred during summer by culturing cut runner plants with 2.5 leaves at 30°C for 5 days after pretreatment at 5°C in the refrigerator for 2 days in the dark.