The effects of various defoliation treatments on flower initiation were studied in the strawberry var. Talisman, which is a facultative short-day plant, with particular reference to differences in the inductive capacity of leaves of differing maturity.
Plants from which all mature leaves had been removed to leave only two immature leaves flowered in longer photoperiods than intact controls, and conversely plants bearing only three fully mature and no immature leaves required a shorter photoperiod for flower initiation than intact plants.
Intact plants in constant darkness and totally defoliated plants in continuous light both initiated flowers, but intact plants in continuous light failed to flower.
It is submitted that these results provide evidence that the photoperiodic control of flowering in this plant operates through a flower inhibitor produced in the leaves.
They also show that although leaves of any maturity are able to inhibit flower initiation, under some conditions mature leaves are more inhibitory than immature, and that the inhibitory activity of any leaf decreases with decreasing photoperiod.