EFFECT OF MALEIC HYDRAZIDE ON NORMAL AND ATYPICAL GROWTH OF RUMEX ACETOSA

Abstract

THE GENERAL AIM of the work reported here was to study the effect of maleic hydrazide (MH) on both the normal and pathological growth of sorrel (Rumex acetosa L.). The specific objectives of this study were to investigate: (1) effects of MH on in vitro cultured pathological tissue, (2) effects of MH on seed germination and early growth, and (3) general effects of MH on mature Rumex plants. Since the discovery that MH has an effect on plant growth (Schoene and Hoffman, 1949), many workers have studied the effects of this compound on normal growth, but no studies have been made on its effect on pathological growth. In general, most reports agree that MH differs from most growth-controlling chemicals in that it causes only inhibition of growth with no formative effects (Naylor and Davis, 1950; Nickell, 1952; Wittwer et al., 1950; Zukel, 1950a,b). It has been reported, however, that MH causes formative effects on sugar beet and cotton seedlings following its application in a spray (Crafts et al., 1950; Erickson and Price, 1950). The possibility of its use as a general herbistat seems excellent. However, there is considerable doubt of its value as a selective herbicide. The mechanism of its action is unknown, but experiments aimed at solving this problem are in progress. Publications to date which might have a bearing on this subiject suggest: it acts in opposition to the natural hormones in plants (Leopold and Klein, 1951); it affects the dehydrogenase enzymes (Isenberg et al., 1951) ; it is antimitotic in its action rather than affecting cell elongation (Deysson and Rollen, 1951; Greulach, 1951; Greulach and Atchison, 1950; see also Darlington and McLeish, 1951); it affects carbohydrate metabolism, causing an accumulation of carbohydrates and the appearance of anthocyanins (Currier et al., 1951; Greulach, 1950; Moore, 1950; Naylor, 1951; Navlor and Davis. 1950; Zukel, 1950a); and it inhibits respiration of root tips (Naylor and Davis. 1951). These suggestions as to the mechanism of action of MH are still quite tentative and subject to revision as more data are secured. In the work reported here the studv of the effect of MH on the growth of virus tumor tissue in vitro has been stressed because: (a) tissue culture techniques afford extremely rigid control of experimental conditions; (b) it is possible to study the effect on one type of tissue without having to con-