205 Effect of Different Pre-Harvest Conditions on the Postharvest Keeping Quality of Cut Gerbera E. Davarynejad, A. Tehranifar, Z. Ghayoor and G.H. Davarynejad Department of Horticulture Ferdowsi University of Mashhad Iran Keywords: Gerbera hybrida, vase life, temperature, light condition Abstract The horticultural product marketability is strongly affected by quality loss during the postharvest chain. Production of floricultural plants in greenhouses is possible by controlling several growth conditions such as air temperature, air humidity, light intensity and quality, plant density and nutrition. According to the growth strategy many combinations of these conditions are possible. The initial state at the harvest time depends on pre-harvest condition. The aim of the present study was the measurement of the effects of different pre-harvest conditions on postharvest behavior of cut gerbera. Two cultivars of gerbera were grown at different air temperatures (20, 24 and 28°C) with two light regimes (natural and supplementary lighting) and then subjected to same postharvest condition. Vase life and bending incidence of cut scapes of two gerbera cultivars, ‘Red Explosion’ and ‘Fiction’ were determined during storage at 25°C. We observed that low and high air temperature negatively affected keeping quality. In addition, supplementary lighting during stem elongation may intensify this trend in some treatments. INTRODUCTION All growers that produce fresh flowers for either local market or exportation need to move their product from the field to their consumers or store at low temperature for different period of time. It is absolutely essential to have a procedure that ensures a high quality product and minimum loss of quality especially during the storage period. Postharvest quality of cut flowers is influenced by both pre-harvest and postharvest conditions. The growth condition and production method may have dramatic impacts on postharvest quality. The objective of most projects related to postharvest life is to determine whether postharvest condition, chemical treatments and preservatives improved the vase life of the flowers. But vase life behavior of fresh cut products also depends on pre-harvest condi- tions. The main factors affecting vase life and bud opening of cut Freesia are temperature, light level, CO 2 level, and relative humidity during growth (Slootweg, 2005). Variability in postharvest quality of product is present among cultivars, seasons, and growers and even between lots of the same grower at the same time of the year. It was concluded that at least some of the problems with the keeping quality of rose are related to poor control of the greenhouse climate (Mortensen and Gislerod, 2000). Growth conditions such as temperature, light, humidity and nutrition affect water relations, carbohydrate balance and development during growth period. Climatic factors particularly temperature and light intensity, greatly influence the uptake and metabolism of mineral nutrients by plants and accumulation of carbohydrates (Fjeld, 1992), which might affect postharvest physiology and perhaps vase life of cut flowers. For example continuous lighting during growth period, dramatically affects the vase life of some rose cultivars (Mortensen and Fjeld, 1998). Supplementary lighting can both increase and reduce the postproduction quality of plants (Fjeld, 1992). The longevity of the individual flower of cut roses was reduced with supplementary lighting during summer months (Hendriks, 2001). The objective of this experiment was to determine whether there are pre-harvest conditions that are essential for maximizing improve the vase life of the cut flowers of Gerbera hybrida. Proc. EURASIA Sym. on Quality Management in Postharvest Systems Eds.: S. Kanlayanarat et al. Acta Hort. 804, ISHS 2008