PLANT WIZARDRY

Wairarapa Times-Age, 1 November 1943, Page 4

PLANT WIZARDRY

THE USE OF HORMONES

SEEDLESS FRUITS MADE.

SOME REMARKABLE DEVELOPMENTS RECORDED.

Remarkable developments in horticulture, fruitgrowing and agriculture are within sight as the result of experiments made in the United States with hormones, chemical substances which are produced in plants and animals and which serve to stimulate, retard or modify natural functions. Although the work is still only in the laboratory stage, much more has been accomplished than could have been predicted even five years ago. At the Boyce Thompson Institute for Plant Research, at Yonkers, New York, extraordinary effects have been produced upon plants by the application of hormones and hormone-like substances. Although plant hormones can be isolated and identified chemically, it is difficult to separate them in sufficient quantities for experiments on plants. Consequently, they have to be made in the laboratory from animal substances. The procedure is carried further by preparing synthetic compounds which are chemically akin to particular hormones, and which do not necessarily occur in plants or animals. Some of these are found to be more active than the hormones to which they arc related. VARIED EFFECTS. When applied to plants, some of these substances produce marked effects. For instance, they may prevent buds of tubers, corms, cuttings and trees from growing. Thus potatoes after treatment may be stored indefinitely without much shrinkage, fruit trees may be prevented from flowering until after the risk ,of frost is over, fruit crops may be spread over longer periods than normal, and apples may be prevented from dropping before harvest. An even more important effect of some substances is to cause flowers to form fruit without pollination. In this way it is 'possible to produce seedless tomatoes with a delicious flavour, slightly sweeter than normal. Seedless peppers, egg-plant, cucumbers, and squash have also been grown. Although it would be most convenient to get rid of the seeds in watermelons, the latter have so far resisted all attacks. Yet another use of hormones and their* kin is to induce plant cuttings to sprout vigorous roots and leaves, but it has not yet been shown that hormone treatment is of any benefit in transplanting. Some of the compounds make extraordinary changes in the habit of growth of various plants, but whether these changes are of practical value is not clear. MEANS OF APPLICATION. 'The substances are applied in several ways. They may be applied to flowers . er buds in a lanolin ointment, may be added to the soil, sprayed in watery solutions, or disseminated in vapour. '. All flowers in a greenhouse of 2500 cubic feet were caused to set by vap- • prising five milligrams of one .sub- i stance on a hot plate and agitating the ‘ air with an electric fan. The potency ( •of some hormones is shown by the fact that the substance known as crocin, ( which is responsible for the yellow j colour of crocuses, has been found to . produce an effect at the amazing dilu- ‘ tion of one part in 250,000,000,000,000. , As few as five molecules of it can be ‘ detected. ,

Some claims made for the application of hormones to plants are regarded as unproven at present, particularly the treatment of seed before planting, and the mixing of the substances with fertilisers. The whole subject presents an enormous field for research, and the practical possibilities it holds out can hardly be realised.