The Effect of Maleic Hydrazide on Certain Dehydrogenases in Tissues of Onion Plants

Abstract

Using a triphenyltetrazolium chloride technic, the authors de monstrated that homogenized tissues of the underground parts of onions grown, in one series in full sunlight and in another in complete darkness, examined in the former case at 20 and 50 days after appln. of maleic hydrazide solns. for 3 successive days, and in the latter case 7 days after appln. of such solns., always produced less triphenylformazan than did tissues from controls when incubated under standard conditions with buffered solns. of succinate, fumarate, malate, or pyruvate extracts. The maleic hydrazide solns. used were made up in concns. equivalent to O (control), 1000, 2000, or 3000 ppm. of the free hydrazide. The results indicate that maleic hydrazide sprayed upon the foliage of plants affects respiration through the partial inactiva-tion or inhibition of one or more of the dehydrogenases. The rapidity of the effects of the chemical is apparently governed by the rate of its absorption in the plant.