Receiving an instruction indicating a source operand and a destination operand. The compound selected from the group consisting of and : 3H-imidazo4,5-d1,2,3triazin-4,6-dione; and 3-methyl-3H-imidazo4,5-d1,2,3triazin-4,6-dione;has a plant growth regulating action. According to this arrangement, even if the oil pressure drops momentarily due to a speed gear shift, the pressure for the hydraulic clutch before the gear shift is held by the hydraulic oil accumulated in the accumulator.