VARIATIONS OF NICOTINE IN THE TOBACCO PLANT.

Rodney and Otamatea Times, Waitemata and Kaipara Gazette, 21 May 1913, Page 7

VARIATIONS OF NICOTINE IN THE TOBACCO PLANT.

The increasing use of tobacco extracts as insecticides has led to the cultivation of tobacco solely for this purpose. Since the insecticidal value of the preparations depends upon the proportion of nicotine they contain, they are usually bought and sold on the basis of the amount of that alkaloid present. It has therefore, become a matter of practical importance to ' ascertain at what period of its growth the tobacco plant is richest in nicotine. For estimating the proportions of nicotine in the growing plant, seeds were sown on April 25th, and' analyses were made of different parts of the young plants at irregular intervals. On May 15th no nicotine could be detected, but a month later the leaves contained 0.35 per cent., and the roots 0.15 per cent. By August 9th the nicotine in the leaves had increased to 3.12 per cent., and in the roots to 0.69, while on September 18th, the date on which the leaves were gathered, the corresponding amounts were 4.79 per cent, in the leaves and 0.64 per cent. in the roots. The stalks contained about the same proportion of nicotine as the> roots, while the amount in the shoots varied from 0.49 to over 1 per cent. Hence the ordinary method of collection, in which only the leaves are selected, involves a\ considerable loss of nicotine, and it is suggested that a means might be devised for extracting the alkaloid from the waste portions of * the plant and to utilise the final residues, for manure.