parameters, the importance of light

parameters, the importance of light quality for morphogenesis has
been reported in many plant species. Plants sense light quality via
photoreceptors categorized as phytochromes, cryptochromes and
phototropins, and these photoreceptors are in charge of a wide
spectrum of morphogenesis (Lin, 2000; Takemiya et al., 2005).
Among them, phytochromes are red and far-red light-sensitive
but cryptochromes and phototrophins absorb blue (B) light (Lin,
2000). Extended stem length has been shown to occur as a part of a
phytochrome-mediated response (Patil et al., 2003). In chrysanthemums,
extended stem length is promoted under a low ratio
of red to far-red light conditions (Rajapakse et al., 1993; Khattak
and Pearson, 2006) or supplemental far-red light irradiation (Lund
et al., 2007; Hisamatsu et al., 2008). Hisamatsu et al. (2008) found
that, compared to controls, irradiation with far-red light reduces
flowering transition when close to critical day length threshold,
and suggested that it is involved in the photo-conversion of phytochromes.
Thus, far-red light affects stem length extension and/or
flowering transition in chrysanthemums. However, far-red light
has not been shown to affect either plant-mass accumulation (Lund
et al., 2007) or to stabilize the flowering transition depending on
photoperiod (Hisamatsu et al., 2008).
In contrast to phytochromes, B light related-photoreceptors
have also been suggested to be involved in the flowering process
(Hirose et al., 2006; Fankhauser and Ulm, 2011). It has been