Über den Einfluß von 2.4-Dinitrophenol auf Atmung und Wachstum in vitro kultivierter Maiswurzeln

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Abstract
2,4-dinitrophenol (2,4-DNP) causes an increase in respiration up to 120% in carrot tissue. Only the undissociated molecule is effective. A curve for the effect of 2,4-DNP independent of pH has been calculated. Of the 3 mono-nitrophenols, p-nitrophenol causes a great increase in respiration while both the others are only slightly effective. Likewise, 2,5- and 2,6-DNP are ineffective. The addition of weak concns. of 2,4-DNP to the substrate, in addition to causing an increase in respiration, also accelerates the elongation of maize roots grown in vitro. In time this acceleration changes to a retardation which successively affects N-assmilation, growth in length, dry weight, and finally also the intensity of respiration. The acceleration of differentiation by weak concns. of DNP can not be explained by the assumption of an uncoupling of dehydration and phosphorylation as the only working mechanism of DNP.