The Effect of Interrupting Short Day Cycles with Day-length Extension on Floral Bud Initiation in Strawberry (Fragaria × ananasa)

Abstract

Experiments were conducted to investigate the potential effect on floral bud initiation in strawberry (Fragaria × ananasa, cv. Chandler) by interrupting inductive short day cycles with a day-length extension treatment. Vegetative plants were exposed to 10-, 15-, or 20-day cycles of inductive short days in growth chambers. After receiving an inductive short day treatment plants were transferred to a greenhouse where they were exposed to non-inductive long days, which stimulated panicle elongation. Dissections of apical meristems immediately following each cycle of short days revealed that cycles of 20 days resulted in detectable floral bud formation. After 15 days in the greenhouse, all short day treatments had initiated floral buds. In the greenhouse, under long days, subsequent flowering in cohorts of plants which had previously received inductive short days showed a positive correlation between interruption of short days with day length extension and reduction in the number of floral buds initiated on earliest emerging panicles. These results suggest potential for manipulation of floral bud induction and potentially fruit size in Chandler, and perhaps other cultivars by interruption of a cycle of inductive short days with a day length extension treatment.