NEW MATERIAL: A pyrimidine compd. represented by formula I (wherein Y is 3-7C secondary or tertiary alkyl, 3-7C cycloalkyl or alkylcycloalkyl, R1 and R2 are same or different and H or lower alkyl, A is a heterocyclic group, n is 0-2, R2 is H, 1-4C alkyl, 2-4C alkenyl or 2-4C alkynyl) and its stereoisomer and an agricultural-chemically aceptable salt of the compd. represented by formula I and a metal complex thereof and an ester (acylate) of the compd. represented by formula I (wherein R3 is H).

EXAMPLE: 3-Hydrxy-4-methyl-3-pyrimidin-5-yl-1-thien-3-ylpent-1-in.

USE: Useful as a plant growth adjusting agent and a sterilizing agent.

PROCESS: For example, a compd. represented by formula II and a compd. represented by formula III (wherein M is a metal such as lithium of an organometal compd.) are reacted to obtain the compd. represented by formula I.