Studies on the physiological mechanism of maleic hydrazide to the subterranean crops and seeds. (I)

Abstract

The effect of MH on the respiration of onion bulbs and potato tubers was studied at the end of 5months after harvest. The leaves of onion (Yellow Danvers Flat) were sprayed with 0.25% solu-tion of MH 2 weeks before the harvest, and the potato plants (Irish Cobbler) were similary treated with 0. 1, 0.2, 0.3 and 0.5% solution of MH 3weeks before the harvest. The experimental results are summarized as follows. 1. The onion bulbs; (a) The decrease in oxygen uptake in the disk part (bottom part)of the treated bulb was observed in comparision with the control, while the _??_ifference in leaf part (scaly leaf) was not signi-_??_cant in this respect. The same tendency was also _??_bserved in the experiment in vitro. (b) Respiratory quotient (R. Q.) in the disk _??_art of treated onions was less than the control, _??_ut in the leaf part the value was larger than he control. (c) The activity of dehydrogenase and catalase in the onion disk part treated with MH was less than the untreated onion. 2. The potato tubers; (a) The respiration of potato tubers was stimulated at all degrees of the concentration of MH throughout the experiment, especially it was remarkable by the application of 0.5%MH. (b) R. Q. value in the treated tubers was always less than the untreated one as it was found in the disk part of onion. (c) Dehydrogenase and catalase activities increased with treatment, not alike in the case of the onion bulb. 3. It seems appropriate to conclude that the growth inhibition and the physiological disorder of onion bulbs and potato tubers received MH treatment must have been induced by the disturbance of the respiratory mechanism and/or the alteration of metabolic pathway.