Crop Productivity Efficiency of Petunias in the Greenhouse

Crop productivity efficiencies (CPE) of around 8% (the ratio of the dry weight gain of the crop to the potential to produce dry weight), were realized with petunias ( Petunia hybrida Villm.), provided that the crop canopy was essentially closed at the beginning of the 9- to 12-day experimental periods and that there were many branches (sinks). This was found at either long or short photoperiods or at either a normal (15.6°C) or reduced (7.2°) temperature for the 16-hour night periods. Long photoperiods resulted in significantly increased CPE through increased size of the leaves before the crop canopy was closed. Elevated root temperature increased CPE after a sizeable number of lateral branches had formed.