MALONIC ACID AS AN INHIBITOR OF MAIZE ROOT RESPIRATION

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Abstract
The influence of pH on the response to malonate was shown to be typical of its influence on the behavior of other weak acids; there is no evidence that it penetrates predominatly as the monobasic ion. At pH 4 as the concn. of malonate was increased above 10-3 [image], O2 uptake and CO2 output were inhibited in such a way that the R.Q. was progressively raised towards 2. In concns. greater than 10-2 [image] anaerobic respiration also was inhibited. Associated with the high R.Q. in air in the presence of malonate, there was an accumulation of the fermentation products alcohol and acetaldehyde. It is suggested that reactions other than succinic dehydrogenation are affected when strong inhibitions of respiration are observed. The origin of acetaldehyde and alcohol is considered to be some of the pyruvate which is not used when the cyclic breakdown system is inhibited by malonate.