A method for increasing the yield of staple food crops comprising contacting a compound represented by the following general formula (I) with a plant for cultivating staple food crops (excluding seeds). Examples include moss. In the following general formula (I), R1 and R2 each independently represent a hydrogen atom or a monovalent substituent, or an azo group in which R1 and R2 are connected to each other, and R3 represents a hydrogen atom or a monovalent substituent. . [Chemical 1]下記一般式（Ｉ）で表される化合物と、主食作物の栽培用植物体（種子を除く）とを接触させることを含む主食作物生産増収方法であり、主食作物としては、好ましくは穀物類又は芋類などが挙げられる。下記一般式（Ｉ）中、Ｒ１及びＲ２はそれぞれ独立して水素原子もしくは１価の置換基、又はＲ１とＲ２が互いに連結したアゾ基を表し、Ｒ３は水素原子又は１価の置換基を表す。【化１】
