Under these conditions, the plants experience a shortage of moisture, and this apparently promotes the formation of papaverine in the opium. The years 1946 at Krasnodar and 1950 at Tartu were hot, dry ones, whereas 1947 and 1951 were very wet. So far it has not been possible to establish any clear principles governing changes in the thebaine and narcotine contents of the opium. The total alkaloids content of the opium is a little higher in northern districts than in southern ones, but it cannot be concluded from this that alkaloids form more readily in the northern districts, seeing that the absolute yield of alkaloids is considerably greater in the south owing to the heavier opium crop. The percentage content in the six main alkaloids and the total alkaloids content of the opium are subject to variation according to the soil and climatic conditions of the district where the poppy is grown.
Lower temperatures promote the formation of codeine.
A drop in morphine content as a result of any particular set of conditions is accompanied by an increase in codeine content. The Biochemistry of Cultivated Plants , Vol. 8, 1948. USSR , No. 6, 1937. First All-Union Geographical Congress, No. 3, 1934. The Chemistry of Fats , 1934.