Top wheat producers in 2020 Country Millions of tonnes China 134.2 India 107.6 Russia 85.9 United States 49.7 Canada 35.2 France 30.1 Pakistan 25.2 Ukraine 24.9 Germany 22.2 Turkey 20.5 Wheat is widely cultivated cereal, spread from 57ºN to 47ºS latitude. Hence, wheat is cultivated and harvested throughout the year in one country or other. China, India, Russian federation, USA, France, Canada, Germany, Pakistan, Australia and Turkey are most important wheat growing countries. ECONOMIC IMPORTANCE Wheat is the world's number one cereal in area. Cultivation of wheat is as old as civilization. It is the first mentioned crop in Bible. Wheat is eaten in various forms by more than 1000 million people in the world. In India, it is second important staple food crop next to rice. In areas wheat is staple cereal food; it is eaten in the form of 'chapattis'. In areas where rice is the staple cereal food, wheat is eaten in the form of 'puris' or in the form of 'upma' (cooked from 'suji' or 'rawa'). In addition to this, wheat is also consumed in various other preparations such as 'dalia', 'halwa', 'sweet meals', etc. In most of the urban areas of the country, the use of backed leavened bread, flakes, cakes, biscuits, etc. is increasing at a fast rate. Besides staple food to human, wheat straw is a good source of feed for a large population of cattle in the country. SOIL AND CLIMATIC REQUIREMENT Soils with a clay loam or loam texture, good structure and moderate water holding capacity are ideal for wheat cultivation. Care should be taken to avoid very porous and excessively drained soils. Soil should be neutral in its reaction. Heavy soils with good drainage are suitable for wheat cultivation under dry conditions. These soils absorb and retain in rain water well. Heavy soils with poor structure and poor drainage are not suitable as wheat is sensible to water logging. Wheat can be successfully grown on lighter soils provided their water and nutrient holding capacities are improved. Climate Wheat has hardening ability after germination. It can germinate at temperature just above 4ºC. After germination it can withstand freezing temperatures by as low as -9.4ºC (Spring wheat) and as low as -31.6ºC (Winter wheat). Normal process starts above 5ºC under the presence of adequate sunlight. Wheat can be exposed to low temperature during vegetative and high temperature and long days during reproductive phases. Optimum temperature is 20-22ºC. Optimum temperature for vegetative stage is 16-22ºC. Temperature above 22ºC decreases the plant height, root length and tiller number. Heading is accelerated as temperature rose from 22 to 34ºC, but, retarded above 34ºC. At grain development stage, temperature of 25ºC for 4-5 weeks is optimum and above 25ºC reduces the grain weight. It is long day plant. Long day hastens the flowering and short day increase the vegetative period. But, after the release of photo-insensitive varieties, no issues of photo-sensitiveness.
The given content explains Thomas S. Kuhn’s model of scientific development , its application to geography, and criticisms by Karl Popper, Paul Feyerabend, Michel Foucault , and others. 1. Basic Idea Kuhn argued that science does not develop continuously in a straight line . Instead, scientific development occurs through: Preparadigm → Paradigm → Normal Science → Crisis → Scientific Revolution → New Paradigm A new paradigm may replace an older one, producing a major change in the way scientists understand and study a subject. Concepts and Terminologies Concept / Term Simple Meaning Paradigm A commonly accepted framework/model that guides scientific research Exemplar A successful concrete problem-solution used as a model for future research Disciplinary Matrix Shared beliefs, values, concepts, methods and techniques of a scientific community Preparadig...
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