Plant Growth-Substances

Abstract

A RECENT report in the Kew Bulletin describes experiments conducted in co-operation with the garden staff but designed by Dr. C. R. Metcalfe and Dr. W. G. Templeman to test the influence of synthetic growth-substances upon the rooting of cuttings of many plants ("Experiments with Plant Growth-Substances for the Rooting of Cuttings”. By C. R. Metcalfe and W. G. Templeman. Bull. Misc. Information, No. 8; 1939). Their results show that some 45 per cent of the species they selected have responded favourably to one or other of the treatments, which included the use of solutions of indolylacetic acid, indolylbutyric acid, and α-naphthylacetic acid, at different concentrations. The list of plants is a thoroughly representative one including many well known to practical propagators to be exceedingly difficult to root from cuttings. Their successes include some seventeen plants already listed by the Plant Hormone Committee as difficult to propagate in this way, but their results also show that other difficult plants have failed to respond to the treatments. The tabular presentation of the data affords ready reference, and many nurserymen and gardeners generally will consult their list, which, however, contains records of failures with a few species which have been successfully propagated elsewhere at perhaps other seasons of the year. It is hoped that this work will be extended to include tests of these substances applied in powder form.