A pot experiment was conducted during 2004–2005 on opium poppy (Papaver somniferum L.) and the influence of 10−6 M gibberellic acid (GA3) and 10−6 M triacontanol (TRIA) either alone or together, on the growth, yield, quality and morphine content. Among the treatments, foliar spray of GA3+TRIA significantly promoted the values of most of the physiological and biochemical parameters including the opium yield. The morphine content was also enhanced. The effects of GA3 and TRIA were similar when given individually, in general, while only TRIA induced branching in the plants. Another important finding of this experiment was that GA3+TRIA favoured the branching as well as the development of capsules at the same levels of height in all the branches. This influence will bring about a practical benefit by facilitating easier manual or mechanical lancing of the capsules, the collection of the latex and the harvesting of the opium poppies. Thus, we conclude that 10−6 M each of GA3 and TRIA given together may be used for maximizing the yield of opium and morphine.
