Dehydrogenase activities recorded at the surface of roots of intact plants (in vivo) and in root enzyme extracts (in vitro).

Root systems of intact plants were incubated in 100 mM phosphate buffer (pH 7.6) containing triphenyltetrazolium chloride at 37°C. Root enzyme extracts were incubated with triphenyltetrazolium chloride and NADH at 37°C. Dehydrogenase activity was determined in terms of nmoles of triphenylformazan formed. Values represent mean ± standard error (n = 5). Dehydrogenase activities recorded at the surface of roots of intact plants (in vivo) and in root enzyme extracts (in vitro).