ACTION OF LIGHT ON ROOTING IN VITRO AND ACCLIMATIZATION OF SEQUOIA SEMPERVIRENS TO SOIL
White light at various irradiance levels, night breaks with red and far-red light, and 9 hour and 16 hour photoperiods are applied to cuttings of two clones of Sequoia sempervirens on a rooting medium in vitro. High light irradiance improves rooting percent, increases the number of roots and decreases root length of a mature, difficult-to-root clone. At low and medium irradiances, a 16 hour photoperiod appears to increase rooting percentage but this is probably due to an increase in the total irradiance and not an effect of phytochrome because night breaks by red and far red light do not alter rooting. Greenhouse acclimatization of a juvenile, easy-to-root clone is quickened when cuttings are rooted under high irradiance. Acclimatization of this clone could be affected by the phytochrome system since night breaks by far red light during rooting hasten acclimatization and this effect is reversed by red light. Acclimatization of a difficult-to-root clone depends on the length of time that cuttings grow in an agar medium : cuttings should be transferred to soil quickly after roots are initiated to avoid the formation of large callus and soft, spongy roots.
WALKER, N., JACQUES, R. and MIGINIAC, E. (1987). ACTION OF LIGHT ON ROOTING IN VITRO AND ACCLIMATIZATION OF SEQUOIA SEMPERVIRENS TO SOIL. Acta Hortic. 212, 289-302