Classification Of Crops PDF

Classification of Crops There are more than 600 cultivated plant species. About 100200 species play an important role in world trade. Only 15 plant species represent the most important economic crops. Why classification require...

Classification of Crops There are more than 600 cultivated plant species. About 100200 species play an important role in world trade. Only 15 plant species represent the most important economic crops. Why classification required? To get acquainted with crops. To understand the requirement of soil & water for different crops. To know adaptability of crops. To know the growing habit of crops. To understand climatic requirements of different crops. To know the economic produce of the crop plant & its use. To know the growing season of the crop. To know the actual condition required for the cultivation of the plant. Field crops are classified according to different standpoints:  Botanical classification.  Agronomic classification.  Special-purpose classification.  Classification according to life span.  Classification according to root depth.  Classification according to growth habit.  Classification according to CO2 fixation.  Classification according to mode of pollination. 1. Botanical Classification (e.g., Maize) Binomial system Each crop plant has two names; the genus and the species. The genus starts with a capital letter, whereas the species name is small. Triticum aestivum L. L. signifies that the Swedish botanist Carl Linnaeus named it. Classification of Crops 1  Sometimes a crop can be renamed by another scientist. Glycine max L, Merr. Botanical classification  Monocotyledons: Gramineae: includes wheat, barley, rice, maize, oat, sugar cane, sorghum, rye grass, and Sudan grass. Liliaceae: includes onion and garlic.  Dicotyledons: Leguminosae: includes field bean, lupine, chickpea, lentil, fenugreek, Egyptian clover, alfalfa, soybean, peanut, grass pea, castor bean, red clover, and white clover. Malvaceae: includes cotton. Linaceae: includes flax. Solanaceae: includes potato, tomato, and tobacco. Pedaliaceae: includes sesame. Composite: includes sunflower and safflower. 2. Agronomic classification  Cereal or grain crops Cereals are grasses grown for their edible seeds such as wheat, oats, barley, rye, rice, maize, and grain sorghum.  Legumes of seeds: includes fababean, peanut, fenugreek, lupine, cowpea, soybean, chickpea, and lentil.  Sugar crops: includes sugar beet and sugar cane.  Oil crops: includes flax, soybean, peanut, sunflower, safflower, sesame, castor bean, and rape.  Fiber crops: includes cotton, flax, jute, sisal, and ramie.  Fodder crops: includes alfalfa, Egyptian clover, sorghum, Sudan grass, grass pea, lablab, Napier grass, millet, white clover, and red clover.  Rubber crops: includes para rubber, Castilla rubber, and guayule.  Tuber crops: includes potatoes and Jerusalem artichoke.  Root crops: includes sweet potatoes and sugar beet.  Medical plants: includes castor bean and others.  Stimulates: includes tobacco, tea, and coffee. 3. Special-purpose classification  Catch or emergency crops: substitute crops that have failed due to unfavorable conditions. They are usually quick- growing crops, such as toria, fodder, rye, millet, and clover.  Cash crop: any crop grown to generate cash rather than for subsistence. Some crops may be cash crops one year but not the next, or for one farmer but not another.  Cover crops: these crops are planted to provide a cover for the soil and to prevent erosion such as green manures, pulses, and clover.  Green manure crops: these crops are turned under while still green to improve soil properties and increase organic matter content. Several field crops can be used such as Egyptian clover, lupine, and cowpea.  Companion crops: a crop can be intercropped with another one and each crop is harvested separately. For example, mustard in sugarcane, wheat in sugarcane, onion and garlic in cotton crop, or soybean in maize.  Silage crops: these crops are preserved in a succulent condition by partial fermentation in a tight receptacle. They include corn, sorghum, forage grasses, and legumes. 4. Classification according to life span  Annual crops: these plants complete their entire life cycle from seed to seed in a single growing season and then die. Most field crops are considered annual crops such as wheat, barley, rice, maize, sorghum, safflower, and others. Classification of Crops 2   Biennial crops: these plants complete their life cycle in two seasons. Vegetative growth occurs during the 1st season resulting in a rosette form but plants donʼt flower. In the 2nd season, the green plants give flowers and seeds. The crops of this category are onion and sugar beet. If you expose sugar beet plants, grown in the first year to low temperature they can start blooming and flowering and behave as annual crops.  Perennial crops: these crops are grown in the soil for more than two years (they can persist for more than two years). They may either produce seed or not every year. In other words, they have an indefinite life period. They do not die after reproduction but continue to grow indefinitely from year to year. Sugarcane and alfalfa are examples of perennial crops. 5. Classification according to root depth  Shallow root crops: the root system of these crops extends in the soil to a depth of one meter such as wheat, barley, and rye.  Intermediate root crops: the depth of the root system of these crops ranges from 11.5 meters in the case of fababean and sugar beet.  Deep root crops: the root system of these plants extends in the soil to a depth of more than 1.5 meters as in alfalfa. 6. Classification according to growing season  Winter crops: these crops are usually planted in October and November and most of their life cycle occurs in the winter and spring season. They are often harvested in April and May. Examples of these crops are wheat, barley, fababean, lentil, chickpea, etc.  Summer crops: these crops are usually planted at the beginning of the spring season and most of their life cycle occurs in the summer season. They are often harvested in September. Examples of these crops are maize, summer mungbean, summer urdbean, etc.  Rainy season crops: sowing starts in May/June and harvested in October/November. Examples include rice, cotton, wheat, mungbean. Classification Based on Season:  Kharif Crops: The Kharif/monsoon crop is sown with the beginning of the first rains in May/June to July, during the southwest monsoon season and harvested in October. The term Kharif means “autumnˮ in Arabic, e.g., paddy, maize, soybean, sorghum, groundnut, cotton, urd, etc.  Rabi Crops: The Rabi/winter crop or spring harvest crop is sown in November during the northeast monsoon season and harvested in February. The term Rabi means “springˮ in Arabic, e.g., wheat, chickpea, pea, sunflower, safflower, mustard, etc.  Zaid Crops: The Zaid/summer crop is mainly sown in March and harvested in May. Requires warm day weather for major growth period and longer day length for flowering e.g., moongbean, sunflower, maize, etc. 7. Classification according to CO2 fixation  C3 Plants: Net assimilation rate in these plants is low 1540 mg CO2/day) but compensation point is high 3070 ppm). Stomata are open during the day. Photo-respiration is high in these plants so C3 plants have lower water use efficiency. The initial product of C assimilation is the three ‘Cʼ compounds. The enzyme involved in the primary carboxylation is ribulose-1,biophosphate carboxylase. Examples include rice, soybeans, wheat, barley, cotton, potato. C3 plants include more than 95 per cent of the plant species on earth. Trees, for example, are C3 plants.)  C4 Plants: Net assimilation rate in these plants is high 4080 mg CO2/day) but compensation point is low 015 ppm). Stomata are open during the day. The primary product of C fixation is four carbon compounds which may be malic acid or aspartic acid. The enzymes responsible for carboxylation are phosphoenolpyruvate carboxylase which has a high affinity for CO2 and is capable of assimilating CO2 even at lower concentration, photorespiration is negligible. These are said to be Classification of Crops 3  drought-resistant & they are able to grow better even under moisture stress. C4 plants translate photosynthates rapidly. Examples include sorghum, maize, sesame, etc.  CAM plants: CAM stands for Crassulacean Acid Metabolism) The stomata open at night. During the day stomata are closed. Large amounts of CO2 are fixed as malic acid which is stored in vacuoles. There is no possibility of CO2 entry. CO2 which is stored as malic acid is broken down & released as CO2. In these plants, there is negligible transpiration. C4 & CAM plants have high water use efficiency. These are highly drought-resistant. Examples include pineapple, sisal & agave. 8. Classification according to the mode of pollination  Naturally self-pollinated crops: the predominant mode of pollination in these plants is self-pollination in which both pollen and embryo sac are produced in the same floral structure or in different flowers but within the same plant. Examples: rice, wheat, okra, tobacco, tomato.  Naturally cross-pollinated crops: pollen transfer in these plants is from the anther of one flower to the stigma of another flower in a separate plant, although self-pollination may reach 5 per cent or more. Examples: maize and many grasses, avocado, grape, mango, many plants with unisexual or imperfect flowers.  Both self-and cross-pollinated crops: Examples: cotton and sorghum. Classification According to Taxonomy Classification of Crops 4  Asteraceae/Composite : includes sunflower, safflower, niger. Cruciferae: includes mustard, radish, cabbage, cauliflower, etc. Cucurbitaceae: includes bottle gourd, bitter gourd, pumpkin, etc. Chenopodiaceae: includes sugar beet, beet, spinach. Euphorbiaceae: includes castor, tapioca. Malvaceae: includes cotton, ladyfinger, rosette. Papilionaceae/Leguminosae: includes pea, gram, arhar, groundnut, berseem, lathyrus, sunhemp, lucerne, urd, moong, lentil, soybean, etc. Linaceae: includes linseed. Pedaliaceae: includes sesame (til). Poaceae/Graminae: includes cereals, millets, grasses, sugarcane, napier, oat. Polygonaceae: includes buckwheat. Solanaceae: includes potato, tobacco, tomato, chili, brinjal. Classification Based on Root System:  Tap root system: The main root goes deep into the soil. Examples: tur, grape, cotton.  Adventitious/Fiber rooted: The crops whose roots are fibrous shallow & spreading into the soil. Examples: cereal crops, wheat, rice, etc. Classification Based on the number of Cotyledons:  Monocots or monocotyledons: Having one cotyledon in the seed. Examples: all cereals & millets.  Dicots or dicotyledonous: Crops having two cotyledons in the seed. Examples: all legumes & pulses. Classification based on climate:  Tropical: Crops grow well in warm & hot climates. Examples: rice, sugarcane, jowar, etc.  Temperate: Crops grow well in cool climates. Examples: wheat, oats, gram, potato, etc. Classification based on cultural method/water:  Rainfed: crops grow only on rainwater. Examples: jowar, bajara, mung, etc.  Irrigated crops: Crops grow with the help of irrigation water. Examples: chili, sugarcane, banana, papaya, etc. Classification based on economic importance:  Cash crop: Grown for earning money. Examples: sugarcane, cotton.  Food crops: Grown for raising food grain for the population and fodder for cattle. Examples: jowar, wheat, rice, etc. Classification based on the length of photoperiod required for floral initiation:  Short-day plants: Flower initiation takes place when days are short less than the critical period of day length (may be less than ten hours). Examples: rice, jowar, green gram, black gram, etc.  Long day plants: require long days are more than the critical period of day length (may be more than ten hours) for floral initiation. Examples: wheat, barley.  Day neutral plants: Photoperiod does not have much influence on phase change for these plants. Examples: cotton, sunflower. The rate of the flowering initiation depends on how short or long is the photoperiod. Shorter the days, more rapid initiation of flowering in short days plants. Longer the days, more rapid is the initiation of flowering in long days plants. Classification of Crops 5