2022 Volume 91 Issue 1 Pages 1-7
We applied the New Root-zone Environmental Control System (N.RECS), which comprises floor heating panels with chilled or heated water flow and heat-insulating pot trays, to cool the root zone of pot-grown strawberry (Fragaria × ananassa Duch.) nurseries in late summer, and investigated the effects on the subsequent flowering and yield in a super-forcing culture. Cooling at around 20°C with short-day (8-h daylength) treatment for 22 days accelerated and stabilized the flower bud formation of two June-bearing cultivars, ‘Nyoho’ and ‘Tochiotome’. The temperature at the soil surface, where the crown is located, was around 23°C on average during root-zone cooling, possibly acting as a cold stimulus on the shoot apical meristem, which initiated flowering. Root-zone cooling did not affect the development of new leaves during treatment. Combined root-zone cooling with short-day treatment promoted anthesis of the first inflorescence to the same degree as conventional night cooling, but neither did so alone. Weight-based early marketable yield before December was doubled but the total yield during October to March was not increased. These data suggest that root-zone cooling with short-day treatment of June-bearing strawberries may be applicable for super-forcing culture harvested from October to mid-November.
