The Role of Light in Tissue Culture

01 Light Intensity

Light intensity plays a significant role in the proliferation of cultured cells and the differentiation of organs. Current studies show that light intensity has a noticeable effect on the initial division of explants and cells. Generally, strong light intensity results in sturdy seedling growth, while weak light tends to cause seedlings to become elongated. Under dark conditions, plants exhibit characteristics such as thin stems, long internodes, fragile structure (underdeveloped mechanical tissue), small and curled leaves, poorly developed roots, and an overall yellowish appearance—a phenomenon known as etiolation.

02 Light Quality

Light quality significantly influences callus induction, tissue proliferation, and organ differentiation. For example, in lilies, bulblets cultured under red light develop callus after 8 weeks, whereas under blue light, callus appears only after several weeks. For Gladiolus cormlets, buds appear first when cultured under blue light 15 days after inoculation, and the resulting seedlings grow vigorously. In contrast, under white light, the seedlings are thin and weak. With technological advancements, LED lights have become increasingly popular in tissue culture due to their high efficiency, low energy consumption, safety, durability, and spectral wavelengths that align with the requirements for photosynthesis and photomorphogenesis.

03 Photoperiod (Light Duration)

In tissue culture of plantlets, a specific light/dark cycle is necessary, with the most commonly used cycle being 16 hours of light and 8 hours of darkness. Studies show that for photoperiod-sensitive plant varieties, short-day conditions favor organ differentiation, while long-day conditions promote callus formation. In some cases, dark incubation is essential, especially for certain plants whose callus grows better in the dark, such as safflower. Except for certain materials that require darkness for callus induction, most cultures require an appropriate amount of light.

Illuminated Incubators

Illuminated incubators are biological culture devices with built-in lighting functions. They are mainly used for tissue and cell culture, seed germination, seedling cultivation, and microbial growth. When equipped with light-shielding hoods, they can simulate day-night light cycles in coordination with timing functions.