Abstract
BACKGROUND: Chilling is traditionally assessed in France based on the number of hours below 7°C. OBJECTIVE: This research was carried out to evaluate the effect of two diurnal temperatures (11°C, 16°C) with a night temperature below 7°C for chilling effect. METHODS: ‘Gariguette’ cv. potted plants were grown with temperatures above 10°C in 2009 and above 14°C in 2010 until the onset of chilling conditions. Plants were transferred into controlled conditions during 68 days and exposed to 11°C/2°C or 16°C/2°C day/night temperatures, to differentiate four treatments: a) “mild” conditions (16°C/2°C day/night); b) “cold” conditions (11°C/ 2°C day/night); c) “mild then cold” conditions (34 days each); d) “cold then mild” conditions (34 days each). Potted plants were then transferred to a heated plastic tunnel for fruit production assessment. RESULTS: The “mild” treatment showed a lower fruit yield than the “cold” treatment. This negative effect of the “mild” treatment was compensated when plants were exposed to the “cold” treatment during half of the chilling duration (“cold then mild” or “mild then cold” treatment). CONCLUSIONS: These results indicated that temperature fluctuations above 7°C have to be taken into account in case of a long chilling.