The effect of end of day far-red light on regulating flowering of short-day strawberry (Fragaria × ananassa Duch. сv. Paros) in a long-day situation

The effects of manipulation of phytochrome state and plant age were tested on flowering strawberry ( Fragaria × ananassa Duch. cv. Paros) using end of day far red light (EOD-FR) under undesirable environmental conditions (high temperature and long day). The first and second experiments examined the effects of EOD-FR on flower induction, level of phytochrome and carbohydrates (starch, sucrose, fructose, and glucose), which were variable along with acid invertase enzyme. In the first experiment, there was no flower emergence, but in the second experiment, induction occurred in plants exposed to 6 h of EOD-FR for 32 cycles. The third experiment tested the effect of far red light (6 h + 32 d) on plants of 8, 10, and 12 weeks of age, and induction occurred in 12-week-old plants. The results of experiments II and III indicated that in the induced plants, the amount of phytochrome (Pr) increased. Furthermore, a higher level of sucrose was observed in induced plants, but the level of starch was lower. Nevertheless, amounts of glucose, fructose, and invertase enzyme did not change significantly, although they did show a slight increase in induced plants. These results provide evidence that a light-quality pathway exists that acts on regulation of flowering time in short-day strawberry cultivation.