PURPOSE: To prevent rice plant from lodging and improve quality by applying zeolite on leaf blades during a period from the neck-node differentiation stage to the reduction division stage of the rice plant, etc.

CONSTITUTION: Zeolite is, e.g. dried with hot air, then ground and used as powder. The aforementioned zeolite is applied onto leaf blades while the morning dew is present during a period from the neck-node differentiation stage to the reduction division stage. Alternately, the ground zeolite may be converted into a suspension at a suitable concentration and sprayed thereon. The aforementioned zeolite is capable of suppressing elongation between parts of hypostatic nodes through stomata and motor cells of the leaf blades, enhancing photosynthetic ability of the leaf blades, thickening and hardening culms and suppressing lodging.