Honda Motor will halt one of its three automobile assembly lines in Thailand by the end of March, a move that amounts to a capacity reduction in a market short on growth. One of the two lines at the Japanese automaker’s plant in Ayutthaya Province, each of which can roll out 150,000 vehicles a year, will go idle. Honda’s annual production capacity in Thailand will fall to 270,000 vehicles, narrowing a wide gap with output. Thailand is Honda’s main production hub for southeast Asia. Beside the Ayutthaya plant, Honda also has a factory in Prachinburi Province with an assembly line capable of making 120,000 units annually.