Effect of Yeast Extract on the Growth of Plants

Abstract

CULTURE experiments which we have carried out with peas have shown that yeast extract—prepared by heating yeast in water—stimulates to a remarkable extent the development of blossoms. In these experiments, the plants were grown either in sterile culture fluids (pH 6.5) or in quartz sand, watered with Hiltner's nutriment solution. Nitrogen was supplied to the plants either in the form of nitrates or by inoculating the seed with active bacterial strains. When suitable amounts of yeast extract were used, the test plants started blooming 5–10 days earlier than controls (test-plants 20–25 days, controls about 30 days after sowing). The number of pods was invariably some 50 per cent greater when the plants were given yeast extract. Excessive amounts of yeast extract were found to cause deleterious effects. Work is in progress to find out which particular factor in yeast extract is responsible for the stimulating action. Particular attention will be paid to the question whether the factor which stimulates the growth and blooming of plants is identical with the factor stimulating the cell division of micro-organisms.