Pigments formed in etiolated sunflower seedlings

Etiolated plants must be irradiated before chlorophyll can form in them. Chlorophyll develops most readily in young irradiated plants. More carotene develops in seedlings grown from young seeds than in seedlings grown from older ones. There may be a relationship between the viability of seeds and the potential power to produce carotene. Carotinoid-pigment formation precedes chlorophyll formation. Probably some necessary substance is translocated in the plant for the formation of pigment. Carotene and xanthophyll may be precursors of chlorophyll. They probably form a respiratory mechanism for the plant. Carotene may be a precursor of auxin.