Catalase Activity in Rice Shoot Apex during Panicle Initiation

There was a gradual increase in the catalase activity in theshoot apices of the two rice varieties—Ratna and BAM 11,till panicle initiation. Peroxide content in the Ratna shootapices decreased with time and was low during and after panicleinitiation. In Ratna plants, exogenous application of cycloheximideand 3-amino-1,2,4-triazole resulted in a delay in panicle initiationwith a corresponding decrease in catalase activity. Exogenousapplication of hydrogen peroxide caused a rise in catalase activityand delayed panicle initiation in both Ratna and BAM 11 varieties.In BAM 11 plants treated with 28 consecutive short photoinductivecycles there was an earliness in flowering accompanied by anearly peak in catalase activity. (Received May 10, 1985; Accepted August 12, 1985)