Morphogenic Effects of Three Growth Substances on Marchantia gemmalings

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Abstract
Sterile gemmae of Marchantia polymorpha were grown on an agar substrate prepared with inorganic mineral nutrients. Various concentrations of indoleacetic acid, naphthaleneacetic acid, and maleic hydrazide were added, and the progressive morphogenic responses of the developing gemmalings were measured. The two auxins promoted similar responses, many interpretable in terms of those noted in higher plants. Rhizoids elongated on the dorsal surface; the growing region became quiescent, and cells elongated very markedly. A winged thallus was the characteristic response to inhibition of apical growth. The degree of response followed a normal distribution curve. Maleic hydrazide induced pronounced effects at a concentration of 10-1 g/liter, slight ones at 10"^ g/Hter, and none on lesser concentrations. Observed responses, similar to those in higher plants, included inactiva-tion of meristematic regions, deterioration of chloroplasts, hyperplasia, and inhibition of rhizoid production.