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Exploring Biology Topics can reveal the incredible complexity and interconnectedness of living systems.
Approaches Adopted for the Improvement of Crop Yield
Agriculture is the science and practice of farming, which mainly involves rearing livestock, cultivating land, raising crops, harvesting, and marketing the produce.
It is further subdivided into many categories.
- Agronomy: The branch of agricultural science deals with the production of field crops and the management of the soil.
- Horticulture: Branch of agriculture that deals in the growth and management of fruit and flowering plants in orchards and gardens.
- Olericulture: Refers to growing and managing vegetables.
- Aquaculture: The farming and harvesting of plants and animals in bodies of water for economic purposes.
- Agronomist: An agronomist studies crop disease, selective breeding, crop rotation, and climatic factors, tests the soil, investigates the causes of soil erosion, and designs land reclamation and irrigation schemes.
Types of Crops
Crops are plants that are cultivated by humans for food, fodder, fiber, flowers, timber, etc. There are about 2000 plant species that are cultivated for eating purposes. Following parts of the plants are eaten as food.
Seeds:
Not all seeds of plants are edible. For example, large seeds such as those from a lemon pose a choking hazard, whereas seeds from apples and cherries contain poison cyanide. Edible seeds include cereals, pulses, oil seeds, and nuts (dry fruits).
(a) Cereals: They include crops such as wheat, rice, maize, barley, sorghum, etc. They are a rich source of carbohydrates.
(b) Pulses: They include legumes such as chicken pea gram, (chana), pea (matar), black gram (urad), green gram (moong), pigeon pea (arhar), cow pea (lobia) and lentil (masoor). They are an excellent source of proteins.
(c) Oil seed crops: They include cotton seed, niger (Ramtil), safflower, soybean, flax (linseed oil), rapeseed, groundnut, sesame, mustard, sunflower, olive, etc. They are a source of oil, fats, and fatty acids. These seeds are typically high in unsaturated fats and when consumed in moderation are regarded as healthy foods. Coconut oil and palm oil are cheap sources of the cooking medium. (Note: Castor oil is not edible oil. It is mainly used as a lubricant or purgative, in the manufacturing of transparent soaps, inks, paints, phenyls, hair fixers, etc.).
(d) Nuts or Dry fruits: Nuts are rich in proteins and fatty acids, so are considered energetic food items. Examples include almond, walnut, cashew nut, pistachio, fig, raisin (or cufrant), dried apricot, coconut, peanut, date, etc.
Fruits:
They include apples, oranges, mango, banana, pineapple, guava, papaya, watermelon, muskmelon, pomegranate, pear, peach, apricot, grapes, dates, custard apple, etc. Essentially fruits are ripened ovaries of plants and are a good source of vitamins, minerals, roughage, proteins, carbohydrates, and fats.
Vegetables:
They are the edible parts of herbaceous plants. They are eaten in raw or cooked form. Vegetables are of the following types:
(a) Roots: Roots of some plants such as carrots, radishes, turnips, sweet potatoes, and beetroot are eaten as vegetables.
(b) Stems: Stems of some plants such as mustard, bamboo, banana, asparagus, etc., are used as vegetables. Certain plants have modified underground stems that are eaten, e.g., potato, onion, garlic, ginger, etc. Stems of sugarcane are used for making of cane juice and jaggery.
(c) Leafy Vegetables: They include leaves of spinach, lettuce, cabbage, turnip, radish, mustard, methi, bathua (pigweed) and curry-leaf tree.
(d) Inflorescence Vegetables: They include broccoli, cauliflower, etc., of vegetables.
Flowers of banana, fennel, gourd, and saffron are also good examples of vegetables.
(e) Fruit vegetables: They include tomato, pumpkin, brinjal (eggplant), jack fruit, bitter gourd, bottle gourd, ridged gourd, cluster bean, cucumber, lady’s finger, pumpkin (sitaphal), capsicum, lablab bean, vegetable sponge (ghia torai), faraz bean, tamarind, carambola (kamrakh), etc.
Spices:
Certain parts of some plants (e.g., leaves, stems, flowers, fruits and seeds) are used to enhance the palatability of food. They include chilly, turmeric, black pepper, cumin, fenugreek, cardamom, fennel, nutmeg, lovage, sesame, cinnamon, dried ginger (sounth), etc .
Fodder crops:
They provide green fodder to the cattle, e.g., berseem, oat, Sudan grass, sorghum, etc.
Other crops:
Crop plants also yield fibres (e.g., cotton), tobacco, tea, coffee, chocolate, peppermint, etc.
Crop Seasons
Different crop requires different climatic conditions, temperature and photoperiod for their growth and maturity. Sunlight is required for photosynthesis – the process of manufacturing food by green plants. Photoperiods are the duration of sunlight that influences plants in their growth, flowering, formation of storage organs, leaf fall, etc. In India, there are two main seasons of crop growth: Kharif and Rabi.
Kharif Crops:
These crops grow during the rainy season (June to October). They are also called summer season crops. The chief kharif crops (cereals and pulses) are paddy (rice), maize, millet, groundnut, soybean, arhar, black gram (urad), green gram (moong) cotton, and jute. Vegetables of Kharif crops are spinach, gourd, garlic, lady finger, pumpkin, and brinjal. Fruits of Kharif crops are watermelon, muskmelon, mango, litchi, plum, peach, etc.
Rabi Crops:
These crops grow from November to April. Rabi crops are also called winter crops. The important rabi crops (cereals and pulses) are wheat, .barley, gram, mustard, pea, and linseeds. Vegetables of rabi crops are cabbage, cauliflower, carrot, radish, turnip, beans, etc. Fruits of rabi crops are apples, pomegranates, oranges, etc.
Differences between Kharif and Rabi crops
| Kharif Crops | Rabi Crops |
| 1. They are monsoon or rainy-season crops | 1. They are non-monsoon season crops. |
| 2. The crops grow in hot and wet conditions. | 2. The crops grow in cold and nearly dry conditions. |
| 3. These crops are sown at the beginning of the rainy season in June-July. | 3. These crops are sown in October-November when the monsoon retreats. |
| 4. These crops are harvested during September-October at the end of the Monsoon. | 4. These crops are harvested in March-April before the advent of the hot season. |
| 5. Examples: Rice, Maize, Groundnut, Soybean, Green gram, Cotton, and Black gram. | 5. Examples. Wheat, Barley, Gram, Mustard, Linseed, Pea. |
Improvement in Yields
The following three scientific approaches are adopted in India to obtain high yields from our agriculture farms:
- Crop production management
- Crop variety improvement
- Crop protection management
Crop Production Management
India is an agriculture-based country. In this country, the agriculture sector engages about 70% of its population and accounts for 40% of the Gross National Product (GNP). Farming practices being followed depend upon the size of the land holding, education, and financial conditions of the farmers. The production practices include “no-cost” production, “low-cost” production, and “high-cost” production.
High-cost production is based on improved high-yield varieties, improved farming practices, modern technology, latest agricultural machines and implements. Crop production management refers to controlling the various aspects of crop production, to obtain the maximum and best yield. It has the following three components:
- nutrient management
- irrigation
- cropping pattern
India is a large country with an enormous area under cultivation. India is blessed with continuous growing seasons which means that crops can be grown throughout the year. This is due to the subtropical climate, plenty of sunshine, and lack of frost in most parts of the country.
Nutrient Management
Nutrient management means controlling the selection, timing, and amount of nutrient supply to the crops. Like other living organisms, plants also require inorganic elements for building their structure and maintaining their metabolic processes. These inorganic elements are called nutrients. Nutrients are supplied to the plants by air, water, and soil. There are about 40 elements found in plant ash, but only 16 of those elements are essential for plant growth and development. Hence, these 16 elements are called essential elements or essential plant nutrients.
Out of 16 essential elements, two elements, carbon, and oxygen are obtained from air and hydrogen from water. The remaining 13 elements are supplied by the soil. These 13 elements are minerals. A mineral is a substance that is obtained by mining.
16 essential nutrients of plants their sources, types, and examples
| Source | Nutrients | Type |
| 1. Air | Carbon (C), Oxygen (O) | Macronutrients (= 2) |
| 2. Water | Hydrogen (H) | Macronutrient (= 1) |
| 3. Soil | Nitrogen (N), Phosphorus (P), Potassium (K), Calcium (Ca), Magnesium (Mg), Sulphur (S) | Macronutrients (= 6) |
| Iron (Fe), Manganese (Mn), Boron (B), Zinc (Zn), Copper (Cu), Molybdenum (Mo), Chlorine (Cl) | Macronutrients (= 7) |
Types of Essential Nutrients
Maze (1915) divided essential plant nutrients into two categories, macronutrients, and micronutrients.
(i) Macronutrients (Macroelements): They are those essential elements that are present in plants in easily detectable quantities, more than 1 ppm of the plant body (1 mg per gm of dry weight). Macronutrients take part in the synthesis of organic molecules and the development of osmotic potential (Box 1.5). Carbon (from air), oxygen (from air), and hydrogen (from water), are non-mineral micronutrients. Out of 13 essential mineral elements, six are macronutrients, i.e., nitrogen, phosphorus, potassium, calcium, magnesium, and sulphur.
Osmosis: The diffusion of a solvent, such as water, through a semipermeable membrane, which separates two solutions of different concentrations. The flow of the solvent is from the more dilute to the more concentrated solution, owing to the thermodynamic tendency of the solution to equalize the concentrations of solutes on the two sides of the membrane. A better way of defining osmosis is to say that it is net movement of water through a semipermeable membrane from a solution of higher water potential to a solution of lower water potential. Osmosis was studied by Thomas Graham, who coined this term in 1858. Osmosis is important in dialysis and in water transport in living tissue.
(ii) Micronutrients (Microelements): They are those essential elements that are present in plants in small quantities, less than 1 ppm or 1 mg/gram of dry matter. All of them are mineral elements. Micronutrients are mostly involved in the functioning of enzymes. Out of 13 essential mineral elements, seven are micronutrients, i.e., iron, manganese, boron, zinc, copper, molybdenum and chlorine.
Differences between Macronutrients and Micronutrients
| Macronutrients | Micronutrients |
| 1. They are required in large quantities. | 1. They are required in very small amounts. |
| 2. Concentration of each macronutrient in plants is more than 1 mg/gm of dry matter. | 2. Concentration of micronutrients is quite below 1 mg/gm of dry matter. |
| 3. They take part in building plant bodies and different protoplasmic structures. | 3. They have no such functions. |
| 4. They have no significant role in enzyme activity and electron transport. | 4. They are involved in enzyme activity and electron transport. |
| 5. Examples: Nitrogen, Phosphorous, Potassium, Calcium, Magnesium, and Sulphur. | 5. Examples: Iron, Manganese, Boron, Zinc, Copper, Molybdenum, and Chlorine. |
Mineral Replenishment
Soil is the most important reservoir of plant nutrients. Crop plants regularly withdraw minerals (in the form of nutrients) from the soil. Unless and until minerals are replenished at regular intervals, the crop plants will develop disorders in structure, growth, reproduction, functioning, and susceptibility to diseases. Mineral replenishment is done through the addition of manures and fertilizers to the crop fields.