Influence of Maleic Hydrazide on Ripening of Tobacco Leaves

Abstract

Tobacco plants, the variety Bright Yellow, cultivated in field were topped, and then treated with 1 % solution of MH. The leaves harvested were compared with untreated leaves of the control plants regarding the following points: Hastening vs. delay in ripening, differences in leaf constituents, red rust infestation and structural characters of the leaf. The results obtained were summarized as follows: 1) The treated leaves, as a passing phenomenon, turned deeper green, but from two weeks after the treatment, chlorophyll contents began to decrease, and the reflexion value of the leaf increased. 2) In the treated plants, the ripening of leaf judged from the diurnal responsibility of its stomata, showed a tendency usually to be late and did most eagrer with the ripening stage judged by the external appearance or color of the leaf. In the untreated plants, on the contrary, the ripenig of leaf by those two methods agreed well with each other. 3) The ratio of intercellular spaces was found lower, its epidermal cell arrangement more compact, leaf texture harder, and red rust infestatinn lighter, in the treated leaves than in the untreated. 4) The specific gravity of tissue powder, the unit area weight and the drying percentage were all together higher in the treated leaves. 5) Total nitrogen contents of the leaf decreased remarkably after the treatment, while ammonium nitrogen increased conversely. protein contents were very low in the treated leaf and its T. N. / P. N. -value was superior.