Fields Crops and Crop Classification PDF

Lc. No. 5 Fields crops and classification, importance, ecology and ecosystem Introduction: Agriculture is the backbone of India’s economy. The history of agriculture dates back to several centuries. Since time immemorial, crops and plants were grown and domesticated by the people, in severa...

Lc. No. 5 Fields crops and classification, importance, ecology and ecosystem Introduction: Agriculture is the backbone of India’s economy. The history of agriculture dates back to several centuries. Since time immemorial, crops and plants were grown and domesticated by the people, in several parts of the world. Plants which are fully useful for human and animal consumption have been segregated and cultivated in farms and fields. In Geographic studies, the area of cultivation of crops and plants, factors of their growth, their distribution and yield are analyzed with reference to space and time. Crop classification is a fundamental aspect of agriculture, as it provides a systematic way to categorize and understand the diverse array of plants cultivated for various purposes. It explores how crops are categorized based on various criteria, such as their use, growth characteristics, and botanical features. Understanding crop classification is essential for effective agricultural management, crop selection, and sustainable farming practices. It is well known that there are more than 600 cultivated plant species. From which there are about 100- 200 species play important role in the world trade. However, only fifteen plant species represent the most important economic crops. Therefore, these crop species must be classified or grouped in a convenient way to facilitate communication, dissemination and retrieval of scientific information as well as promotes the conservation, and improvement of certain plants. Generally, classification of these species is important for these reasons: 1. To get acquainted with crops. 2. To understand the requirement of soil & and water for different crops. 3. To know the adaptability of crops. 4. To know the growing habits of crops. 5. To understand the climatic requirements of different crops. 6. To know the economic produce of the crop plant & and its use. 7. To know the growing season of the crop 37  8. Overall to know the actual conditions required for the cultivation of plants. Field crop: Any of the herbaceous plants grown on a large scale in cultivated fields: primarily a grain, forage, sugar, oil, or fiber crop. Ecology: The scientific study of the interactions between organisms and environment. The term comes from the Greek 'study of house', or the study of the place we live in. The scope of ecology is huge, and it encompasses all organisms living on Earth and their physical and chemical surroundings. Ecosystem: An ecosystem is a structural and functional unit of ecology where the living organisms interact with each other and the surrounding environment. In other words, an ecosystem is a chain of interactions between organisms and their environment. The term “Ecosystem” was first coined by A. G. Tansley, an English botanist, in 1935. An ecosystem is defined as a community of lifeforms in concurrence with non- living components, interacting with each other. Types of Crop Classification: Globally, major crop classifications are defined by the Food and Agriculture Organization (FAO) of the United Nations. For a better understanding of agricultural crops and their distribution in India and the globe, knowledge of the classification of plants and crops is needed. Crop classification can be approached from different angles. This section discusses various classification criteria: Descriptive Classification of Crops: The descriptive classification of crops is based on five criterions: a) Mode of Reproduction: The method adopted according to the Mode of Reproduction, has classified the crops into two major divisions as sexual and asexual reproducing plants. The Sexual category of plants are developed from a seed or spore after undergoing union of male and female gametes. The typical examples 38 include palms and ferns. The Asexual category of plants undergo reproduction by any vegetative means without the union of the sexual gametes or by apomixis. b) Mode of Pollination: This criterion divides plants into three categories as: 1. Naturally self-pollinated crops: In the Naturally self-pollinated plants, both pollen and embryo sac are produced in the same floral structure or in different f lowers but within the same plant. Typical Examples include: rice, most pulses, okra, tobacco, tomato. 2. Naturally cross-pollinated crops: In the Naturally cross-pollinated crops, the pollen transfer is done from one flower to the stigma of another flower in a separate plant. Typical examples include, corn and many grasses, avocado, grape, mango, many plants with unisexual or imperfect flowers. 3. Both self- and cross-pollinated crops: In both self- and cross-pollinated crops, plants are largely self-pollinated but varying amounts of cross-pollination also occur. Examples include, cotton and sorghum. c) Life Span: According to Life Span, crops are classified into annuals, biennial and perennial categories. 1. Annual: The Annuals are plants which live within a short period of time, for a few weeks or months, perpetuated by seed, and which die soon after producing seeds. Examples include: rice, corn, cowpea, etc. 2. Biennials: The Biennials are plants which requires two growing seasons to complete its life cycle, the first for vegetative growth and accumulation of food reserves, and the second for the production of reproductive parts. Examples include: onion, cabbage, carrot, celery, and raddish. 3. Perennials: The Perennials include, a plant that lives indefinitely, including all trees and shrubs and many herbaceous plants with underground stems (e.g. corm, rhizome, tuber) like banana and clump-forming grasses. The Perennial plants continue growing and produce seeds year after year, either from a single plant or, in herbaceous plants, from succeeding regrowth. 39 d) Growth Habit: Based on Growth Habit crops classified into Herbs, Vines, Lianas, Shrubs and Trees. e) Leaf Retention: According to leaf retention, plants are classified into Evergreen plants and deciduous plants. 1. Evergreen plants: The Evergreen plants are those that maintain their leaves throughout the year. Abscised leaves are continually replaced by new flushes. Examples include pines, banana, papaya, palms and most tropical plants. 2. Deciduous plants: The Deciduous plants are those which naturally shed off or lose leaves annually for extended periods. Natural leaf shedding is pronounced in deciduous trees of temperate regions. e) Classification of Crops based on the Ecological Adaptation or Habitat: Geography and ecology are two inter-related subjects. Most of the ecosystems are studied under geographic contexts, The plants are also classified according to their ecological adaptation and habitat. The major classes of plants are: i) Aquatic / hydrophytic plants: The Aquatic/ hydrophytic plants are adapted to growing in water or waterlogged soil. They grow entirely in submerged, partly submerged or floating, or conditions. Examples: lotus and water lily. ii) Epiphytes or epiphytic plants: The Epiphyte or epiphytic plants grow above ground on another plant but is not parasitic, usually deriving only physical support from the host and obtaining nourishment from the air and other sources. The most common epiphytes belong to the pineapple, orchid, and fern families. iii) Halophytes or halophytic plants: The Halophytes grow in habitats excessively rich in salts or under saline conditions. Mangrove vegetation are good examples. Coconut, cashew and tamarind have varying levels of tolerance to saline conditions. iv) Lithophyte or lithophytic plants: The Lithophytes are adapted to grow on rocks or in rocky terrain with little humus, absorbing nutrients from the atmosphere, rain, and decaying matter which accumulate on the rocks. 40 v) Mesophytes or mesophytic plants: The Mesophytes are terrestrial plants which are adapted to moderate conditions for growth, i.e., not too dry and not too wet (e.g., corn and most commercially-grown crops). vi) Parasite or parasitic plants: The Parasite or parasitic plants grow on another plant from which it takes part or all nourishment. (e.g., Cuscuta, Loranthus, Orobanche, striga etc.) vii) Saprophyte or saprophytic plants: The Saprophyte or saprophytic crops grow on decaying organic matter and has no green tissue. This classification applies to the mushrooms, which are fungi. viii) Sciophyte or sciophytic plants: The Sciophytes grow in low light intensity or shade, e.g., most ferns and mosses, black pepper, coffee, hot pepper, gingers, and many orchids can tolerate or require shade. ix) Terrestrial or land plants: The Terrestrial or land plants grow on land. Most agricultural crops are terrestrial plants. They are further subclassified into various groups such as halophytes, mesophytes etc. x) Xerophyte/ xerophytic plants: The Xerophytes are adapted to conditions with little or no water. Ex: cacti and many succulents. Agricultural Classification: A crop is any useful plant, or a plant which is grown for any purpose. It is utilized by people directly or indirectly, raw or processed. These plants are intentionally grown or managed for various uses. On the basis of tradition, extent of cultivation and intensity of culture, agricultural crops are classified into two main divisions: agronomic and horticultural. f) Based on Use/Agronomic classification: The Agronomic crops are also called as “field crops”. They are mostly annual herbaceous plants that are grown under extensive or large-scale culture. The agronomic classification of plants/ crops based on their primary uses include the following classes: 41 i) Food Crops: The Food Crops are plants grown primarily for the harvesting of any part which is used by people as food or processed into food product. ii) Cash crops: The Non-food Crops are mainly cash crops. These are plants grown for the production of non-food products such as fiber, fodder, alcohol and tobacco. iii) Staple crops: The Staple Crops are food crops. These are regularly consumed in a traditional diet and from which people obtain a major proportion of their energy and nutrient requirements. Examples of other staple crops: wheat and millet. iv) Cereal or Grain crops: The Cereal or Grain Crops are mainly annual, herbaceous plants belonging to the grass family which are grown for their seeds or grains. Examples: corn, millet, rice, sorghum, wheat. v) Legume or Seed crops or Pulses: The Legume Seed Crops or Pulses are leguminous plants which produce edible, protein-rich seeds. Examples: cowpea, peanut and peas. vi) Root and Tuber Crops or Tuberous Crops: The Root and Tubers crops are plants with modified, swollen root or underground stem. These organs are rich sources of carbohydrate and are commonly used as staple, livestock feed, or as raw materials for industrial purposes, such as starch and alcohol production, or processed into various food products. vii) Oilseed Crops: The Oil Seed Crops are plants grown for their seeds which are rich source of edible and industrial oil. Example: sunflower. viii) Sugar and Sweetener Crops: The Sugar and sweetener Crops are plants grown primarily for the production of sugar or other sweet tasting products. Various forms of sugar are derived from various parts of certain plants such as from stems, bulb and other underground organs, leaves, flowers, fruits, seeds, sap and resin. These are called as sugar crops. ix) Beverage Crops: The Beverage Crops are plants which are sources of various drinks including fruit juices. Examples: coffee and tea. 42 x) Rubber Crops: The Rubber Crops are another major type of plants that are grown for the production of latex which is processed into the industrial product called rubber. xi) Latex and Gum Crops: The Latex and Gum Crops are very typical plants. These plants are grown for the collection of latex which is processed into chewing gum, inelastic rubber and other industrial products such as surgical tapes and dental supplies, insulation, splints, pipes, golf balls, waterproofing, adhesives, etc. xii) Dye and Tannin Crops: The Dye and Tannin Crops are special kinds of plants. These plants are grown as sources of tannin and coloring substances. Tannin is an aromatic, phenolic substance which is obtained from barks and other plant organs and variously used in tanning, medicines, dyeing, ink manufacture, etc. xiii) Fiber Crops: Fiber Crops are plants grown as sources of fiber used in making textiles, ropes, twine and similar materials. The fiber is extracted from the bark, leaves, or other organs including the husk of coconut. xiv) Pasture and Forage crops: The Pasture and Forage Crops are very essential varieties of plants. These plants are grown or managed as vegetable feed for grazing animals. Soilage Crops are the grasses grown, cut and directly fed to animals. Silage Crops are the grasses grown, cut, fermented and preserved before being fed to animals. The Biofuel Crops are special type of crops. xv) Biofuel Crops: These plants are grown for the production of fuel that is used as additive or replacement for petroleum products. Examples: sugarcane, corn, coconut, castor bean and Jatropha. g) Horticultural Crops/Plants: Horticultural crops have been referred to as “garden crops”. Horticultural crops are annual and perennial plants which are grown under an intensive system of agriculture. The following are the major kind of horticultural crops: Olericulture or Vegetable Crops: 43 Vegetable Crops are (except mushroom) grown for their succulent and edible parts such as the roots, stems, leaves, young tops, fruits or seeds for use in culinary preparations either fresh or preserved in the fresh state. Vegetables are classified based on their edible parts, into several varieties. They are: i) Leafy Vegetables: Leafy Vegetables are crops that are grown mainly for their leaves. Examples: amaranth, lettuce, and raddish. ii) Shoot Vegetables: Shoot Vegetables are plants grown primarily for their edible shoot, mainly the young, succulent stem. Examples: asparagus and celery. iii) Pod and Seed Vegetables: Pod and Seed Vegetables are generally members of Leguminosae or Fabaceae family. These plants are grown for their young pods and seeds. Examples: beans and sweet corn. iv) Root and Bulb Vegetables: Root and Bulb Vegetables are plants grown for their swollen underground roots and stems. Examples: carrot, potato, onion and raddish. v) Flower Vegetables: Flower Vegetables are plants with edible flowers. Examples: rose and sunflower. vi) Fruit Vegetables: Fruit Vegetables are grown for their fleshy, succulent fruits. Examples: eggplant, tomato, peppers and melons. h) Vegetables are also classified according to their families, into the following groups: i) Cole Crops or Crucifers: These vegetable crops belong to the Cruciferae or Brassicaceae (Mustard) family. They possess edible leaves or heads. Examples: cabbage, cauliflower, mustard, and raddish. ii) Cucurbits: belong to the Gourd and Squash family. They are grown mainly for their fruits but some have edible young shoots and flowers; also called Vine Crops. Examples: bottle gourd, cucumber and melons. 44 iii) Legume Vegetables: Legume Vegetables are the members of the Leguminosae or Fabaceae (Bean) family. The seeds are rich in protein. Examples: kidney beans, pea and pole sitao. iv) Lilies: Members of the Liliaceae (Lily) family. Examples: Asparagus, garlic and onion. v) Solanaceous Crops: belong to the Solanaceae (Nightshade or Egg plant) family and, with the exception of white potato, are also called Fruit Vegetables. Examples: egg plant, tomato, peppers and white potato. vi) Mushrooms: These are edible fungi belonging to the division Basidiomycota (club fungi). The edible part commonly consists of an upright stalk and an umbrella- shaped cap. Fruit Crops and Nuts: The Fruit Crops and Nuts include plants that are grown primarily for their edible fruits. Nuts are grown for their fruits which are high in fat. The nut is a simple, dry, indehiscent fruit with a hard outer covering. Ex: is the cashew. Spice Crops: The Spice Crops are grown for the production of aromatic substances which are used as food flavoring, fragrance or preservative qualities. Spices are in solid or liquid forms. Examples: black pepper, garlic, ginger, hot pepper, onion and turmeric. Essential-oil Crops: The Essential-oil Crops are plants grown for the extraction of essential oils which are volatile, aromatic substances for perfumery and other uses. Examples: eucalyptus, peppermint, etc. Ornamental and Other Plantation Crops Gardening is a part of agriculture. Horticultural cultivation of garden plants is a major area of economy. The Ornamental Crops are plants that are grown primarily for decoration or landscaping or to be appreciated because of their attractive flowers or foliage. They also include floricultural crops. Floriculture: Floricultural crops are valued for their attractive flowers, foliage ornamentals for their leaves. 45 The Lawn or Turf Grasses are grasses grown for aesthetic purpose in the landscape or for any outdoor recreational use. They are usually maintained at a low height. Example: Bermuda grass. i) The ornamental plants are further classified into several varieties, based on their usage, as: i) Cut flowers: The Cut flowers are obtained from plants that are grown for their attractive flowers with long shelf life. Example: anthurium. ii) Cut foliage: The Cut foliage are obtained from plants that are grown for their attractive foliage which are cut for floral decoration. Example: ferns. iii) Edge Crops: The Edge Crops are the short- statured plants that are grown to serve as barrier between the lawn and garden, to highlight gardens, or to create stand-alone gardens; also called border plants. Examples: Mondo grass and dwarf cucharita. iv) Ground covers: The Groundcovers are low-lying, aesthetically appealing plants grown in the landscape primarily to suppress weed growth and to control, retard or prevent soil erosion by covering and binding loose, bare soil. It is used to produce a carpeting effect. v) Hedges: The Hedges are plants grown at the edges of pathways or boundaries and continuously pruned to knee - high height or upper but below eye level. vi) Accents: The Accents are plants with showy features distinct from the rest of the other plants. It immediately attracts attention and becomes a focal item in the landscape garden and at the same time provides the contrast which gives attention to other plants. vii) Specimens: The Specimens are obtained from plants that have showy features, or with unique characteristics which make them pieces of conversation or botanical curiosity, or otherwise desired as collector’s item. viii) Screens: The Screens are plants grown to serve as barrier against sun rays, to conceal certain parts of the landscape, or to obstruct view. 46 ix) Shade crops: The Shade crops are generally trees, shrubs, trellised vines and lianas which are grown mainly to provide shade singly or with supporting trellis. x) Avenue Trees: The Avenue Trees are mainly trees and shrubs grown, more or less equidistant, beside roads and streets. Palms are also used. In addition to these, there are two more categories of plantation crops. One is Biocidal Crops and another Industrial Crops. Biocidal Crops: The Biocidal Crops are plants containing organic compounds with pesticidal or anti-microbial properties. The effective parts are either directly applied or seeped in water for foliar spray. j) Industrial Crops: The Industrial Crops are plants grown to provide materials for industrial processing and production of non-food products, including drugs. The crop names which we use in the farmland are also included under the plantation crops category. They include: i) Main Crop: Any crop which is intended by the grower to become his main source of revenue is called as the Main Crop. ii) Nursery Crop: A plant which is temporarily grown in the nursery and later planted in the field or garden or used for ornamental display, when it reaches the proper age and size, is called as a Nursery crop. iii) Intercrop: The Intercrop is any crop which is planted simultaneously with or before the flowering season of the main crop in intercropping. iv) Filler Crop: The Filler Crop is any crop which is planted to fill a gap. The Relay Crop is the crop which is planted after the flowering period or harvest of the main crop in relay cropping. v) Companion Crop: The Companion crop is any crop which is planted close to the main crop to complement the latter’s growth and production, or to maximize utilization of space because they do not compete. vi) Cover Crop: The Cover crop is a crop grown mainly to control soil erosion, regulate soil temperature, control weeds and reduce evaporative losses. 47 vii) Green Manure Crop: The Green manure crop is a leguminous crop grown to be ploughed under the soil to increase organic matter and serve as organic fertilizer. Mung bean (mungo) is ideal for this purpose. viii) Trap Crop or Decoy Crop: The Trap crop or Decoy crop are plants grown to attract certain insect pests or parasites because they are favorite hosts. They act as decoys to lure pests away from the main crop. ix) Insect pest repellent crops: The Insect pest repellent crops are plants grown along the borders and at strategic places in the farm to repel insect pests because of their strong aroma and anti-herbivory properties. x) Natural enemies attractant crops: The Natural enemies attractant crops are flowering plants grown at strategic places in the farm to attract natural enemies of insect pests. Classification based on Cultural Method/Water Rain fed: crops grow only on rain water. E.g., Jowar, Bajra, Mung etc. Irrigated crops: Crops grows with the help of irrigation water. E.g., Chili, sugarcane, Banana, papaya etc. k) Classification based on Root System i) Tap root system: The main root goes deep into the soil. E.g., Tur, Grape, Cotton etc. ii) Adventitious/Fiber rooted: The crops whose roots are fibrous shallow & spreading into the soil. Ex: Cereal crops, wheat, rice etc. l) Classification based on Economic Importance i) Cash crop: Grown for earning money. Ex: Sugarcane, cotton. ii) Food crops: Grown for raising food grain for the population and & fodder for cattle. Ex: Jowar, wheat, rice etc. m) Classification based on No. of Cotyledons: i) Monocots or monocotyledons: Having one cotyledon in the seed. Ex: all cereals & Millets. 48 ii) Dicots or dicotyledonous: Crops having two cotyledons in the seed. Ex: all legumes & pulses. n) Classification based on Photosynthesis’ (Reduction of CO2 /Dark Reaction) i) C3 Plants: Photo respiration is high in these plants C3 Plants have lower water use efficiency. The initial product of C assimilation in the three ‘C’ compounds. The enzyme involved in the primary carboxylation is ribulose-1,-Biophospate carboxylose. Ex: Rice, soybeans, wheat, barley cottons, potato. ii) C4 plants: The primary product of C fixation is four carbon compounds which may be malice acid or acerbic acid. The enzymes responsible for carboxylation are phosphoenol Pyruvic acid carboxylase which has high affinity for CO 2 and capable of assimilation CO2 event at lower concentration, photorespiration is negligible. Photosynthetic rates are higher in C4 than C3 plants for the same amount of stomatal opening. These are said to be drought resistant & they are able to grow better even under moisture stress. C4 plants translate photosynthates rapidly. Ex: Sorghum, maize, napier grass, sesame etc. iii) CAM (Crassulacean acid metabolism) plants: The stomata open at night and large amount of CO2 is fixed as a malice acid which is stored in vacuoles. During day stomata are closed. There is no possibility of CO2 entry. CO2 which is stored as malice acid is broken down & released as CO2. In these plants there is negligible transpiration. C4 & CAM plant have high water use efficiency. These are highly drought resistant. Ex: Pineapple, sisal & agave. o) Classification based on Length of Photoperiod Required for Floral Initiation: Most plants are influenced by relative length of the day & night, especially for floral initiation, the effect on plant is known as photoperiodism depending on the length of photoperiod required for floral ignition, plants are classified as: i) Short-day plants: Flower initiation takes plate when days are short less than ten hours. 49 Ex: rice, Jowar, green gram, black gram etc. ii) Long day’s plants: require long days are more than ten hours for floral ignition. Ex: Wheat, Barley etc. iii) Day neutral plants: Photoperiod does not have much influence for phase change for these plants. Ex: Cotton, sunflower. The rate of the flowering initiation depends on how short or long is photoperiod. Shorter the days, more rapid initiation of f lowering in short days plants. Longer the days more rapid are the initiation of flowering in long days plants. p) Based on seasons: Crops are grouped under the seasons in which their major field duration falls. a) Kharif crops: Crops grown during June-July to September–October which require a warm wet weather during their major period of growth and shorter day length for flowering. Ex. Rice, maize, castor, groundnut. b) Rabi crops: Crops grown during October–November to January-February, which require cold dry weather for their major growth period and longer day length for flowering. Ex. Wheat, mustard, barley, oats, potato, bengal gram, berseem, cabbage and cauliflower. c) Summer crops: Crops grown during February–March to May–June which require warm dry weather for growth and longer day length for flowering. Ex: Black gram, green gram, sesame, cowpea etc. This classification is not a universal one. It only indicates the period when a particular crop is raised. Ex: Kharif rice, kharif maize, rabi maize, summer pulse etc. q) Based on climatic condition: i) Tropical crop - Ex: Coconut, sugarcane ii) Sub-tropical crop – Ex: Rice, cotton iii) Temperate crop – Ex: Wheat, barley 50 iv) Polar crop – Ex: All pines, pasture grasses Conclusion: The extent of cultivation of these crops varies from place to place and depends on such factors as the level of mechanization, adoption of technological advances, farm size, market stability and availability of capital. The classifications of crops are used in collecting the basic data of agriculture and analyse them geographically. We will see the distribution of these crops in India, one by one, later. Crop classification is a multifaceted process that aids in organizing and understanding the vast diversity of crops grown worldwide. By categorizing crops based on their use, growth patterns, and botanical features, farmers, researchers, and policymakers can make informed decisions that contribute to sustainable agriculture and food security. 51