Study of the Exogenous Hormonal Regulation of Leaf Senescence in Two Millets, Setaria italica, L. and Pennisetum typhoides, Burm. 3. Study of Enzyme Activity-I ( Catalase, Peroxidase and Polyphenyl Oxidase)

The present project is aimed at studying the exogenous regulation of leaf senescence in two millets i. e. Setaria italica, L. and Pennisefum typhoides Burm. The present study is confined to the study of excised leaf senescence by using growth regulators as the exogenous agents. Attached leaf study was avoided for the reason that preliminary experiments showed insensitiveness of the leaves of these two millets to growth regulators in the attached condition. In this study three growth regulators were selected, each from three major groups. Benzimidazole (BZI) represented cytokinins and indole acetic acid represented the auxins and GA3 represented the Gibberellins. In the present investigation, the growth regulators had no effect on the catalase activity of S. italica and the effects were inconsistent in P. typhoids. Thus it appears that trends in catalase activity is species specific and cannot be generalized. The activity of peroxidase increased during senescence. There was some stimulation of peroxidase in S. italica. However in P. typhoides the enzyme was insensitive to exogenous agents. Thus peroxidase cannot show the extent of physiological decline in these plants. Polyphenol oxidase activity in S. italica exhibited a continuous increase up to the end of incubation both in dark and light treatments in contrast to P. typhoides where a 48 h fall was noticed.