CLIMATE. The Indo-Gangetic plains form the most important wheat area. The cool winters and the hot summers are very conducive to a good crop of wheat. Based on agroclimatic conditions, the country is broadly divided into five wheat zones. These are as follows:
(i) The North- Western Plains Zone consisting of the plains of Punjab, Haryana, Jammu, Rajasthan (except the south-eastern portion) and western Uttar Pradesh. Here, the irrigated wheat is planted in November and the rain-fed wheat towards the end of October. Harvesting generally starts by the middle of May. This zone is most important among the five zones, and only T. aestivum is exclusively grown there.
(ii) The North-eastern Plains Zone consisting of eastern Uttar Pradesh, Bihar, West Bengal, Assam, Orissa, Manipur, Tripura, Nagaland, Meghalaya, Mizoram, Arunachal and Sikkim. This is also an exclusively T. aestivum area. Owing to the late harvesting of paddy, most of the sowing of the wheat is generally done towards the latter half of November and in the first fortnight of December. Harvesting is done in March- April.
(iii) The Central Zone consists of Madhya Pradesh, Gujarat, south-eastern Rajasthan (Kota and Udaipur divisions) and the Bundelkhand area of Uttar Pradesh. Most of the wheat area (about 75 per cent) in this zone is rain-fed. Both T. aestivum and T. durum are grown in this zone. T. dicoccum is grown in a few pockets in Gujarat. Being predominantly rain-fed, the sowing of wheat in this area depends on the conserved moisture of the soil from the preceding monsoon. Sowing in the rain-fed area commences from the middle of October and goes up to the end of the month. Irrigated wheat, whose acreage varies from state to state in this zone, is panted mostly in November. Harvesting here is a little earlier than in the other two zones mentioned and it commences by the end of February and most of it is over by March. The best – quality durum wheats are produced in this zone. The crop is subjected to occasional frost in the Narbada Valley area of Madhya Pradesh.
(iv) The peninsular zone consists of the southern states of Maharashtra, Andhra Pradesh, Karnataka and Tamil Nadu. All the three species mentioned above, namely aestivum, durum, dicoccum, are grown in this zone. T. durum is the most important species under rain-fed conditions are practically over in October and the irrigated sowings in the first fortnight of November. Most of the harvesting is over in the second half of February. Assured water supply is limited in this zone, but wherever it is available, a good crop of wheat comparable with what is obtained in north-western India is raised.
(v) The northern hill zone consists of the hilly areas of Kashmir, Himachal Pradesh, Uttar Pradesh, West Bengal, Assam and Sikkim. In this zone, the sowing is done in October and the harvesting is done in May-June. The wheat plants remain practically dormant during the cold months from November to March and as the temperature rises in April, the crop starts growing. Wheat is grown in this hill zone up to elevations of 3,658 m above sea level. In the valleys and high mountain ranges, wheat is grown in summer instead of in winter. Here, it is sown in April-May and harvested in September -October. In the northern hill zone, only T. aestivum is grown.