Aristotle, the Greek philosopher, classified animals based on whether they live on land, in water or in the air.Classification of living organismsis based on characteristics and divided the animals into groups and sub-groups.Charles Darwin put forward the idea of evolution in 1859, in his book,The Origin of Species.Ernst Haeckel, Robert Whittaker and Carl Woesehave tried to classify living organisms into broad categories, called kingdoms.Kingdom subgrouping into Phylum for animals or Division for plants, Class, Order, Family, Genus and Species is calledhierarchical classification.The scientific naming or nomenclature was introduced by Carolus Linnaeus. The method of naming of an organism with genus first and the species later is called binomial nomenclature.Conventions followed while writing scientific names includes the name of the genus should begin with a capital letter and the name of the species should begin with a small letter.
Monera includes prokaryotic cells which lack organized nucleus and membrane bound cell organelles. Monera are autotrophic, so they derive their nutrition by synthesizing their own food.Protistaare unicellular and the simplest form of eukaryotes and includes algae, diatoms and protozoans.Most fungiare multicellular and eukaryotic and include mushrooms, rhizopus and mucor.Both fungi and algae together live in a symbiotic relationship, calledlichensFungi decay dead plants and animals to derive their food, hence called saprophytes.Some fungi live in a mutual relationship with blue-green algae, this relationship is called symbiosis.Plantaeincludes all plants that are multicellular and eukaryotic with cell walls made of cellulose.Animaliaincludes all the animals that are multicellular, eukaryotic without cell walls.
Cereals provide carbohydrates, pulses provide proteins, oil seeds provide fats, and vegetables, spices and fruits provide vitamins and minerals.
Kharif crops include paddy, soyabean, maize, cotton, green gram and black gram. Wheat, gram, peas and linseed are rabi crops.
In India, the production of food grains increased 4 times from 1960 to 2000. This increase in food production was due to crop variety improvement, crop production improvement and crop protection management.
Crop variety improvement can be achieved by the process of selection. The criteria for selection are high yield, disease resistance, response to fertilisers, tolerance to climate, etc.
Hybridisation occurs by a cross between two different varieties, which is known as inter-varietal crossing, or between two different genera, known as inter-generic crossing, or between two different species, known as inter-specific crossing.
Crop yield can also be increased by introducing desirable genes into the crop plant. This results in genetically modified crop plants that are able to survive in a drought or flood.
Crop production improvement is the protection of crops that are growing or have been harvested. Nutrient management, irrigation and cropping patterns can help improve crop production.
Air supplies carbon and oxygen. Water supplies hydrogen and oxygen. Soil supplies the remaining 13 nutrients to plants. Among these 13 nutrients, 6 nutrients are used in large quantities by plants, and are called macro-nutrients. The other 7 nutrients are used by plants in smaller quantities, and are called micro-nutrients. A deficiency of these nutrients makes plants prone to diseases.
Manure is produced naturally by the decomposition of animal excreta and plant waste. It contains organic matter, and thus, improves the water-holding capacity in sandy soils, and prevents water logging in clayey soils.
Compost is prepared by decomposing farm waste like livestock excreta, vegetable waste, domestic and sewage waste in pits. This process is called composting.
Compost is also prepared by using earthworms to hasten the decomposition of plant and animal waste. This process is called vermi-composting.
Before sowing seeds, plants like the sunhemp are grown and ploughed into the soil. These green plants enrich the soil with nitrogen and phosphorous. This is called green manure.
The continuous use of chemical fertilisers kills useful micro-organisms and even destroys soil fertility. So chemical fertilisers are being replaced by bio-fertilisers.
In a well, water is collected from the water-bearing strata. Tube wells can tap water from the deeper strata. Water is lifted from tube wells by pumps.
Canals receive water from reservoirs or rivers. The main canal is divided into branched canals to irrigate the fields.
Tanks are small reservoirs, which store run-off water.
Mixed cropping is growing two or more crops simultaneously on the same piece of land, which includes wheat and gram, or groundnut and sunflower.
Inter-cropping is growing two or more crops simultaneously on the same field with some rows of one crop alternating with some rows of another, like soyabean and maize, or finger millet and cowpea. This ensures maximum utilisation of the nutrients, and also prevents pests and diseases of one crop spreading to the other crop in a field.
The difference between mixed cropping and inter-cropping is that in mixed cropping, some rows of one crop alternate with some rows of another, while in inter-cropping, the two crops are sown in alternate rows.
Growing two or three different crops in a year on a piece of land is known as crop rotation. Examples include cereals alternating with legumes, soyabean alternating with maize.
Nurturing crop plants against damage by weeds, pests and disease is known as crop protection management. Weeds can be removed by spraying herbicides or by removing them mechanically.
Weeds like Xanthium, Parthenium and Cyperinus rotundus are unwanted plants in a crop field. They compete with the crop plants for food, space and light, and finally reduce crop growth.
Diseases in plants are caused by pathogens such as bacteria and fungi, and viruses, just like in humans. These pathogens are transmitted through soil, water and air.
Storage losses in crops are due to biotic factors like insects, rodents, fungi, mites and bacteria. Abiotic factors like inappropriate levels of moisture and temperature in the storage area also damage crops.