To curb the tendency among farmers to burn paddy stubble, which is causing large-scale air pollution, the Punjab government said it has signed a memorandum of understanding (MoU) with a Chennai-based company to set up 400 processing plants for converting paddy straw into bio-energy in the state. The plants will become operational before the next paddy season, thus preventing recurrence of the environmental hazard triggered by stubble burning in the current season.