Abstract

BACKGROUND: In red raspberries, two fruiting traits are distinguished, and classified as primocane and floricane fruiting. Primocane cultivars represent greater economic relevance; they are adapted to warm climate zones and have an elongated production period. However, this classification can be complicated since fruiting is affected by both environmental and genetic factors. In 'Heritage', the main cultivar used in Chile, flowering is inhibited in shoots produced the first season when grown in temperate zones with low thermal oscillation. OBJECTIVE: This study evaluated the effect of cold temperature during shoot growth on fruiting parameters in different genotypes. METHODS: Plants of the cultivars 'Autumn Bliss', 'Heritage', 'Meeker' and `Tulameen' were tested at low night temperatures. We evaluated these growing characteristics for each cultivar; days until to first visible floral button, number of floral laterals and meristematic bud differentiation. We also analysed the variations associated with expression of the gene RiTFL1, on flowering inhibition. RESULTS: There is an effect of temperature on flowering, growth and RiTFL1 expression, mainly in cvs. 'Heritage' and 'Meeker'. Flowering was enhanced in 'Heritage', while 'Meeker' exhibited an intermediate behaviour, since seasonal shoots managed to flower with a 60-night cold treatment. In both cultivars, growth was reduced, and RiTFL1 was repressed in cold treated plants. CONCLUSIONS: Genotypes with intermediate behaviour require low temperatures for floral induction, which could be associated with RiTFL1 gene repression with low-temperature treatments.