Studies on Tissue Culture Cattleya Species

III. The Relationship between Seasonal Changes of Phenolics Exuded from Pseudobulb Tissues and Survival Rate of Explants

Abstract

Concerning the browing of liquid media which occasionally takes place in vitro culture of Cattleya shoot tips, the relationship between survival rate of explants and seasonal variation of the amount of browning substrates exuded from the chops of young Cattleya tissues was studied. In addition, effects of rutin supplementation on the survival rate of explants were investigated in this experiment.
1. Browning substrates were exuded in large amounts from the chops of young shoot tips in the period from June to September when the growth of shoots was vigorous and the browning of explants, lateral buds, was also remarkable. The survival rate of explants was consequently reduced to about 30%. On the other hand, a survival rate of more than 70% was attained in the period from November to February when stock plants remained in dormant condition and thus browning of explants and exudation of browning substrates both were restrained markedly.
2. Survival rate of explants was increased up to 60 or more when rutin was added to the liquid culture medium at a concentration of 50ppm during the period from the summer to the fall when many explants usually fail to survive in vitro culture. Optimum concentrations of rutin added to the culture medium were 50 to 100ppm for the tissue culture of Cattleya plants.