Effect of zinc and copper on growth and regenerating cultures of Citrus reticulata blanco

Regenerating cultures of Citrus reticulata were subjected to different concentrations of Zn and Cu in the medium to study their effect on in vitro growth. It was seen that higher dose of Cu was more toxic than Zn for in vitro growth whereas absence of Cu affected the growth and regeneration of cultures more than absence of Zn. High Cu content affected root growth more than shoot growth but high Zn content showed better root growth. Cu inhibits the increase in fresh weight and dry weight of cultures. High Zn gave enhanced growth rate of cultures initially and increased dry weights more than fresh weights of cultures. Absence of Cu and Zn caused reduction in dry weight. Cytological studies showed mitotic abnormalities due to high Zn and Cu but the abnormalities were not very severe.