High Quality Plug-Transplants Produced in a Closed System Enables Pot-Transplant Production of Pansy in the Summer

Abstract

Pansy (Viola x wittrockiana Gams., cv. F1 IYellow) seeds were sown on 288-plug trays on 13 August 1999. After the cotyledons were fully unfolded (14 days after sowing), the young plants were moved into a closed system (growth chamber) or an open system (greenhouse) and grown for 14 days. The plug-transplants produced in the closed system showed greater shoot fresh and dry masses and shorter stems than did those produced in the open system. Root dry masses of the plug-transplants produced in the closed system were almost 2.5-fold greater than those produced in the open system. The plug-transplants from each group were transplanted into plastic pots and grown for 42 days in either of two growth chambers at a constant air temperature of 23°C or 30°C. For both chambers, the PPF was 250 μmol m^-2 s^-1 and the photo-/dark period was 16/8 h d^-1. At harvest, the survival percentage was 55% for the pot-transplants produced in the open system and the growth chamber at 30°C, and the surviving pot-transplants were of too poor quality to be sold. On the other hand, the survival percentage was 100 % for the pot-transplants grown in the growth chamber at 30 °C using the plug-transplants produced in the closed system, and all of the pot-transplants were of high quality. At 23 °C, the shoot fresh and dry masses were greater in the pot-transplants grown using the plug-transplants produced in the closed system.