How to protect wheat and mustard crop from frost in North India?

Light irrigation on the night frost is forecast is the most reliable protection, because wet soil holds heat and keeps the canopy a few degrees warmer. When IMD or your KVK warns of a cold wave, irrigate in the evening, and on very cold clear nights light small smoke fires of dry leaves or weeds on the upwind side to create a haze that reduces radiation loss. A foliar spray of soluble sulphur or even plain water on the plants early before sunrise helps tender crops like potato, gram and mustard. Cover vegetable nursery beds with straw or plastic at night and remove it by morning. Frost is worst on still, clear, dry nights, so keep monitoring the agromet bulletin twice a week.