Abstract
In strawberry propagation, a 35-hole tray (6.5 × 6.5 cm apart and cell volume of 130 mL) is easy to handle and convenient for the establishment of runner cuttings in a nursery. It is also efficient for artificial flower-inducing treatment, such as intermittent low-temperature storage (ILTS). However, flower bud differentiation and consequent flowering are generally later and the effects of ILTS have been inferior compared with 9-cm polyethylene pot- or 24-hole tray-grown plants. In this experiment, we examined the effect of plant spacing of tray grown runner cuttings of ‘Nyoho’, at densities of 17, 25, and 35 plants per tray (50, 70, and 100% PPT, respectively) before flower induction with ILTS treatment on flowering. In 100% PPT, the petiole was significantly longer and the root sugar content per plant was low, compared with 50 and 70% PPT. Each plant grown under 50 or 70% PPT was then planted at 100% PPT, and 9-day ILTS (3 days under ambient conditions inserted between two 3 days at 15°C in the dark) was conducted from 25, 28, and 31 August. In 50% PPT, flowering was early and uniform, but in 100% PPT it was markedly delayed compared with 50 and 70% PPT, when ILTS was conducted earlier. From these results, it is considered that the effectiveness of early ILTS can be improved by plant spacing in the middle stage of tray plant propagation, after the establishment of runner cuttings and before flower-inducing treatment.
