THE EFFECT OF HUMIDITY ON THE PERFORMANCE OF GREENHOUSE GROWN STRAWBERRY

The effects of different humidity levels on summer grown 'Elsanta' strawberry plants were examined in five glasshouse experiments (1995-1999). From planting until the end of harvest the relative humidity was maintained continuously during the day at either 50 % , 70 % or 90 %. An increase in the relative humidity in the greenhouses enhanced vegetative growth. Long term exposure to high humidity significantly increased the leaf area and the length of petioles. However, in some trials more tip burn occurred in emerging leaves and flowers of strawberry plants grown under high humidity conditions. Fruit size was, in most experiments, significantly larger at continuously high humidity. However, in some trials under conditions with extreme high humidity final yield was lower due to a reduced fruit set. To achieve maximum yield, good fruit size and fruit set a relative humidity of 65 to 75 % was considered optimum for summer production of ‘Elsanta’ strawberries. Extreme high humidity had detrimental effects on fruit firmness and shelf life. Fruits became more susceptible to fruit rot infection (Botrytis cin. and Rhizopus spp.) during storage.