Chilling requirements and compensation for the lack of chilling in strawberry

With the development of new production techniques, the behaviour of the plants was altered and presented symptoms of lack of chilling. G. Risser (INRA: National Institute of Agronomical Research) began a study to determine a marker of chilling requirements. CIREF (Inter-regional Research and Experiment Centre on Strawberry) has carried on the program on strawberry dormancy since 1994 to answer two questions: 1. What are the chilling requirements of new promising cultivars: a. To get some knowledge of their adaptation to production areas b. To determine dates of coverage in relation to the amount of chilling accumulated over the winter period 2. New cultural methods are being used (early cropping using plants that did not receive sufficient chilling in natural conditions outdoors, permanent or early covers, heated cultures, giving a compact plant habit with short petioles and peduncles). How can this lack of chilling be compensated? a. By providing artificial chilling in proportion to the amount required by the cultivar (by placing trayplants of early cultivars like Gariguette or Cigaline for one month in cold storage, to obtain a March harvest) b. By night-break treatments (light flashes) when the required amount of chilling is not fulfilled. This paper provides an overview of the research programme to date and highlights some of the important results obtained.