Photoperiod and temperature effect on growth of strawberry plant (Fragariax ananassa Duch.): development of a morphological test to assess the dormancy induction

At the end of summer, the diminution of photoperiod and temperature cause a decrease of vegetative growth and the dormancy of strawberry plants. Altho ugh the decrease in vegetative growth can be measured morphologically, no t est is able to evaluate the decrease in growth potential (i.e. during the d ormancy induction) nor its possible influence on vegetative growth. On the one hand, to estimate this influence biometrically, we have correlated phot operiod and temperature decreases with the vegetative growth decrease of so me strawberry cultivars observed in the field. Results have confirmed the m ajor role of photoperiod, temperature and the effect of growth potential de crease on vegetative growth. Moreover, the results showed that the decrease of vegetative growth was an early event at the end of summer which depende d upon strawberry cultivar. On the other hand, we have measured petiole len gth under standard climatic conditions in a growth chamber, after natural s ummer and autumnal exposures. Observations of strawberry plants under these conditions revealed a decrease of their growth potential which also depend ed upon strawberry cultivar. Results also confirmed the possible action of growth potential decrease on the vegetative growth at the end of summer. Co nsequently, the observation of strawberry plants under standard conditions can be used, as a test, to assess the exact moment of dormancy induction. ( C) 1999 Elsevier Science B.V. All rights reserved.