Further experiments with runner plants of the cultivated strawberry joined in pairs as donor/receptor units are reported. Stolon production was promoted in receptor plants in short days by long-day treatment of donor plants. This was a photoperiodic effect induced by low intensity light. Again, as previously, petiole length was increased and flower induction inhibited by these, or similar treatments. An attempt to demonstrate the translocation and activity of a vegetative-growth- inhibiting, flower-promoting hormone gave negative results.
It is argued that the photoperiodic control of the growth habit is mediated mainly by a transmissible vegetative-growth-promoting and flower-inhibiting hormone, which is produced in leaves and acts at the growing regions.