Light quality affects in vitro adventitious rooting and ex vitro performance of cherry rootstock Colt

The effect of light quality on in vitro rooting of cherry rootstock “Colt” was studied to evaluate adventitious root development, ex vitro acclimatization and plant growth performance. Adventitious rooting was dependent on the light quality to which the microcutting were exposed. Highest number of roots per microcuttings was recorded under dichromatic light (blue + red). This response could be ascribed to the control of a strong synergistic interaction between phytochromes and blue light photoreceptors. Red light was more effective on root elongation than blue light. In this response a strong synergistic interaction between phytochromes and blue light photoreceptors was suggested. The effect of light quality on the number of root/explant affected the plant during acclimation, scoring the highest level of plant survival in the blue-, red- and blue + red-exposed plantlets. The light quality effect was also observed under greenhouse culture conditions, as shown by growth parameters at the end of six months in plants growth. No specific role was observed for the photoequilibrium of phytochrome. The results reported in this work show that plantlets exposed to different light quality, during the in vitro rooting phase, retain the light quality effects in the subsequent plant acclimatization and greenhouse plant growth phase.