An Inhibitor of Plant Growth-produced by Aspergillus wentii Wehmer

Abstract

IN the course of an empirical screening programme we found that culture nitrates of Aspergillus wentii, grown on Raulin–Thom medium (5 per cent glucose) supplemented with 0.1 per cent Difco yeast extract, have a pronounced inhibitory effect on the growth of ‘Meteor’ pea seedlings. When seedlings were sprayed to run-off with undiluted culture nitrate, shoot growth almost ceased for a week and then recommenced slowly. Newly formed internodes were abnormally short; leaflets were very narrow, in extreme cases becoming almost linear; flowers were similarly reduced, being almost apetalous; there was a marked loss of apical dominance, several axillary buds producing dwarfed branches. Newly formed stems and leaves were markedly chlorotic. This abnormal growth persisted throughout the subsequent life of the plants. The leaves sprayed, but not those formed after spraying, developed necrotic spots.