The effect of temperature and photoperiod on the rate of flower initiation and the onset of dormancy in the strawberry (<i>Fragaria</i>x<i>ananassa</i>Duch.)

Abstract

SummaryThe effects of temperature and photoperiod on flower and inflorescence initiation during the autumn were investigated in the strawberry cv. Elsanta. The variation in starch under these environmental conditions was also recorded, to test whether this might provide a useful indicator of the onset of imposed and/or true dormancy. Photoperiod had no effect on the rate of flower initiation or final flower number in the primary, secondary or tertiary inflorescences. Temperature had little effect on the final flower number in the primary inflorescence. However, the rate of flower initiation increased linearly with increasing temperature in the secondary (r2 = 0.98) and tertiary inflorescences (r2 = 0.97), to an optimum of 18.6°C in the secondary and 19.9°C in the tertiary inflorescence, and declined at temperatures above these. The quantity of starch in the roots increased during the autumn, and the rate of increase was negatively correlated with temperature. This indicates that root starch concentration is determined by temperature and therefore is not a useful indicator of the onset of true dormancy in ‘Elsanta’.