The Effect of Colchicine as a Chromosome Doubling Agent for Wheat-Rye Hybrids as Influenced by pH, Method of Application, and Post-Treatment Environment

Hybrids of wheat (Triticum durum) × rye (Secale montanum) (2n = 21) were treated with a 0.06 % solution of colchicine. In the induction of fertile plants, fertile spikes, and seed-set per spike, the root immersion technique was 21.7 %, 14.1 %, and 4.4 % respectively more effective than the use of the inverted vial. Colchicine solutions ranging in pH from 3.5 to 7.5 with the root immersion technique reached the highest frequencies of fertile (or partially fertile) hybrids (77.7 %), and fertile spikes (68.9 %) at a pH 5.5 used for the treatment, although the highest overall percentage of large Q seeds resulted from treatments at low pH (3.5). The overall mean frequency of induced fertile plants was six-fold higher when treated in a growth chamber (19/15 °C day/night temperature and 18 h photoperiod) compared to treatments conducted in a greenhouse. The frequency of euploidy (2n = 42) was found to be highest in the large seed class and lowest, i.e. just about 50 %, in the class of small seeds.