Milestones in wheat (Triticum spp.) agronomy research in India: An overview

A new wheat agronomy was developed after the introduction of dwarf Mexican wheats. The first major finding was the need for shifting the date of sowing from mid-October to mid-November, which created ‘rice-wheat’ cropping system in north India. Further, nitrogen (N) application increased from 20–40 kg N/ha in tall wheats to 100–120 kg N/ha in dwarf wheats. Agronomic experiments also showed the need for adequate P fertilization. Field experiments showed the need for 50% or more of water soluble P in nitrophosphates. It was also brought out that native low P containing ground rock phosphates such as Mussoorie rock phosphate (MRP) could also be used for wheat, provided it is applied along with pyrite or phosphate solubilising bacteria (PSB). The data from on-farm trials confirmed the need for balanced NPK fertilization. The need for application of sulphur and zinc to wheat was later realized. At present multi-nutrient fertilizer recommendations are made for wheat and this has necessitated the development of customized fertilizers. INM studies have shown that about 60 kg N/ha can be saved by Sesbania green manuring or growing dual purpose mungbean during summer after the wheat harvest in ricewheat cropping system. A number of techniques for scheduling irrigation, such as, soil moisture tension, cumulative open pan evaporation (CPE), irrigation depth (ID)/CPE ratio and critical stages of growth were tested and are being used. Weed flora shifted from broad-leaf weeds in tall wheats to grassy weeds in dwarf wheats. Isoproturon initially provided a good control of grassy weeds, but gradually herbicide resistant biotypes developed, specially in Phalaris minor. A number of new herbicides such as, sulfosulfuron, clodinofop etc. were later experimented upon and recommended for controlling P minor and other grassy weeds. Successful weed management in wheat has helped in increasing wheat productivity in the country significantly. Rice-wheat is the dominant cropping system in north India. Other wheat-based cropping systems include plant sugarcane-ratoon–wheat, cotton-wheat, maizewheat and pigeonpea-wheat.