Effects of Lighting Conditions on Leaf Coloration and Pigment Content in Osmanthus fragrans Color Group

The Osmanthus fragrans Color Group is a newly established variety of Osmanthus with vibrant leaf color changes and holds broad application prospects. To elucidate the mechanisms by which light regulates the coloration of Osmanthus fragrans leaves and to optimize cultivation conditions to enhance its ornamental value,this study investigated the effects of light quality,intensity,and duration on leaf color parameters (L^*,a^*,b^*) and pigment content in three variegated Osmanthus fragrans Color Group ('Mintaigui Kui','Yongfujin Cai' and ‘Minnong Guiguan') under controlled artificial lighting conditions. The results showed that the leaf color parameters of variegated Osmanthus fragrans were significantly affected by light quality,light intensity,time,and their interactions. Mintaigui Kui showed the highest L^* value (40.8±3.93) under red light at 400 μmol·m^-2·s^-1,along with high a^* and b^* values.Yongfujin Cai under blue light at the same intensity had an L^* value of 50.40±6.83 and b^* value of 27.99±8.85. Light quality and intensity markedly affect pigment content. White light consistently promotes chlorophyll synthesis across stages,with Mintaigui Kui reaching 0.339 mg·g^-1 in the first stage,increasing to 0.873 mg·g^-1 by the fourth. Blue light boosts early-stage anthocyanin content,while red light enhances late-stage chlorophyll synthesis.Yongfujin Cai exhibited higher chlorophyll content in the third stage under high light intensity and higher anthocyanin content in the first stage under low light intensity. This suggests that high light intensity favors chlorophyll and carotenoid synthesis,whereas low light intensity promotes anthocyanin accumulation.