11. Bract / bracteole development begins approximately 1 2 weeks after the photoperiod is reduced. 12. The ideal photoperiod for the tubers is between 12.5 and 13 hours. 13. The development of these forms has been linked to photoperiod and temperature during growth. 14. Plants that flower in response to photoperiod may have a facultative or obligate response. 15. Not only is singing frequency dependent on the photoperiod but the song repertoire is also. 16. In particular the photoperiod can be altered to imply that it is time to spawn. 17. Moulting is affected by the photoperiod . 18. The photoperiod also impacts the oil content in sesame seed; increased photoperiod increases oil content. 19. The photoperiod also impacts the oil content in sesame seed; increased photoperiod increases oil content. 20. An obligate response means that the plant will only flower if grown under a certain photoperiod .
