Three basic needs of human beings are food, clothing and shelter. For all these, we directly or indirectly depend upon plants. Late (Prof.) P. Maheswari once said, "We are all guests of plants on this earth." What an apt remark on our dependence on plants Modern living, in addition requires many industrial products, the raw materials for many of these again come from plants. Therefore, successful cultivation of plants, on which we depend so much, is of prime importance.
Like man and animals, plants too need wholesome nutrition for healthy growth and development. While man and animals are mobile and can gather their food from wherever it is available, plants are stationary and manufacture their own food from simple inorganic nutrients, relying mostly on what they get from their immediate environment. For successful production of a healthy crop, an in depth knowledge of their nutritional requirements is a must.