Corn chloroplast development in weak fluence rate red light and in weak fluence rate red plus far red light

Corn ( Zea mays L. cv . OP Golden Bantum) was grown under various low irradiances of red light (P fr /P tot ∼ 0.8) and under high irradiance far‐red light containing low amounts of red light (P fr /P tot ∼ 0.05–0.15). Parameters of chloroplast development such as pigments, membrane polypeptides and infrastructure were compared among the various light sources. Results indicate that the requirement for phytochrome is saturated at low ratios of P fr /P tot (<5% P fr ). When the phytochrome requirement is saturated, pigment synthesis assumes major importance and chloroplasi development is directly related to red light irradiance.