Wheat is the main food crop in north and north-western part of the country. The geographical conditions favourable for growth of wheat are as follows : (1) Temperature : Wheat is a rabi crop and requires a cool growing season. Average temperature should be between 10°C to 15°C at the time of sowing, but higher temperatures and bright sunshine is required at the time of harvesting for proper ripening of grains. (2) Rainfall : Wheat requires moderate rainfall of 50 to 75 cm annually, evenly distributed over the growing season. A little winter rain before ripening helps in increasing the yield. (3) Soil: Deep alluvial clayey soils of Northern Plains and even black soil of Deccan are suited for growth of wheat. There are two important wheat-growing zones in the country – the Ganga-Satluj plains in the north-west and black soil region of the Deccan. Punjab, Haryana, Uttar Pradesh, Bihar, Rajasthan and parts of Madhya Pradesh are the major wheat growing states.