THE EFFECT OF THE GASEOUS STATE ON BUD INDUCTION AND SHOOT MULTIPLICATION IN-VITRO IN EASTERN WHITE CEDAR

The effect of vessel type and the gaseous phase on the morphogenic response of Thuja occidentalis L. explants in vitro was studied. Explants were cultured in container types that varied in their degree of gas exchange. Traps for ethylene and CO2 were employed. During shoot bud induction from embryonic explants, the number and elongation of shoot buds improved significantly when gastight, serum-capped flasks were used compared to the foam bung-capped flasks or the regularly used Petri dishes. Elimination of the two gases from the headspace of the flasks either singly or together reduced shoot bud induction and especially elongation of shoots. A similar response was seen during axillary bud development from cultured shoots. Ethylene and CO2 accumulation promoted development and elongation of axillary shoots. An increase in the zeatin concentration in the medium produced a greater number of axillary shoots and higher levels of ethylene in the culture vessels. Removal of CO2 caused gradual death of the shoots, while removal of ethylene alone reduced axillary shoot lengths significantly. Inclusion of aminoethoxyvinylglycine in the medium combined with ethylene traps produced an effect similar to the use of ethylene traps alone.