Classification of Crops based on Life cycle and Uses
Crops plants are classified based on three criteria which are;
Botanical classification – Based on generic and specific names
Agricultural classification – Based on the uses or important of crops to man and animals
Classification based on life cycle – Based on numbers of year or season from germination to harvesting or death.
General Classification of Plants
1. By Growth habit:
Succulent plants – herbaceous or herbs (succulent seed plants possessing self-supporting stems)
Vine – a climbing or trailing herbaceous plant (Liana – a climbing or trailing woody plant)
Trees – having a single central axis
Shrub – having several more or less upright stems
2. By Leaf drops:
Deciduous – no living leaves during dormant (winter) season (apple)
Evergreen – retaining functional leaves throughout the year (spruce)
3. By Life span:
Annuals – plants that normally complete their life cycle during a single growing season (lettuce, spinach, marigold)
Biennials – plant that normally completes its life cycle during a period of two growing seasons (celery, carrot)
Perennials – plants that grow year after year, often taking many years to mature.
4. By Temperature tolerance:
Tender plant – damaged or killed by low temperature
Hardy plant – withstands winter low temperatures
Wood hardy – a whole plant is winter hardy
Flower-bud hardiness – ability of flower buds to survive low winter temperatures (peach, ginkgo tree)
5. By Temperature requirements:
Cool-season crop – prefers cool temperatures (peas, lettuce)
Warm-season crop – prefers warm temperatures (tomato, pepper)
6. By Habitat or Site preference:
Xerophyte – prefers dry sites
Shade plants – prefers low light intensity
Acid loving – prefers low pH soils
Halophyte – prefers salty soils
Plant crops are grouped into three categories according to their life cycles such as;
I) Annual Crops
From the name it is clear that the plants live for one season or less. They complete their life cycle once in a year or a growing season; during which the vegetative and reproductive stages are completed e.g. maize, rice, cowpea, millet, vegetables, cotton, groundnut, etc. Annual plant is one which completes its life cycle from germination to seed formation within one season and then dies usually as a result of complete exhaustion of its food reserve in the process of reproduction. They comprise of several of most beautiful and easily grown plants, widely varying in from habit of growth and colour. Annuals are very effective, grown neither in pots nor in ground. Particular annuals thrive best in particular period of the year. The annuals are conveniently grouped according to season as follows.
1. Rainy Season Annuals: They can stand more in rain than others and therefore grown to flower during rainy season. The time of sowing then would be from April to May in most places e.g. Mary gold, Aster, Zinnia etc.
2. Winter or Cold Season Annuals: The thrive and bloom best during winter. These are sown in September, October e.g. phlox, Antirrithium.
3. Hot weather or Summer season Annuals: They are sown in January – February and blooming period is April, May e.g. Sunflower and Zinnia.
II) Biennial Crops
They complete their life cycle once in two years or two group seasons. In the first year, they undergo the vegetative stages where leaves and roots are produced in abundance, the plant also elongates. But during the second year, the plants undergo reproductive stages where flowers, fruits and seeds are produced e.g carrot, lettuce, cabbage, ginger, cassava, etc. These plants usually requires two years or at least two growing seasons with more or less of a dominant season or lasting season between two completed life cycle. Seed sown in spring or summer, and vegetative growth is completed in first year and in the following spring, flowering and fruiting takes place. Generally the period of growth is 6 to 9 months e.g. Gladioli, Dahlia. No hard and fast line can be drawn between annuals and biennials crops like turnip, carrot, cabbage and onion are classified as biennials.
III) Perennial Crops
Any plant that lives more than two years is a perennial e.g. Mango, Citrus. They complete their life cycle once in three years. In the first two cycles once in three years, they undergo vegetative stages while in the last years, the reproductive stages are completed e.g. rhizome, sugarcane, banana, plantain. A perennial plant that can survive for thirty years and above is called permanent crop e.g. cocoa, kola, mango, oil palm, rubber, coconut, etc.
These crops are classified in to two groups.
i) Herbaceous:
Herbaceous perennials are those with more or less soft succulent stems. In Temperate climates the tips die off after seasons growth but root remains alive and produce new stem and tops on favorable conditions. In other words their tips are annual while ground parts are perennials lie many years and are classified as: a) Trees b) Shrubs c) Vines according to their habit of growth.
a) Trees: Trees are upright in habit and stems take the form of central axis e.g. Mango, guava, Mandarins etc.
b) Shrubs: Shrubs have no main trunk but a number of erect or semi erect stems are seen but do not forms the main frame work e.g. Hibiscus, Rose etc.
c) Vine: Both woody and herbaceous have stems which are flexible and not in position to keep their branches and leaves erect. They either spread on the ground or require some support whether alive or man-made e.g. Grape vines, Passion fruit etc.
Agricultural Classification or classification based on the uses of crops:- In this category crops are classified into the following groups, legumes, cereals, spice, latex, beverages, fibre.
IV) Ephemerals: They are crops that complete their life cycle once in three or four months and can undergo two or three life cycles in a year e.g. tomato
Classification Based on Uses
Food Crops – These are crops used by man for food. They are sub-divided into various groups
Cereal Grains – They are grass crops grown for their seeds or grains which are rich in carbohydrate e.g maize, rice, millet, wheat, sorghum and barley
Grain Legumes – They supply proteins in the food of man. E.g cowpeas, soyabeans, groundnut, pigeon peas.
Root Crops – These are crops grown mainly for food stored in the swollen roots. They are the major sources of carbohydrate e.g cassava, carrots
Tuber Crops – They are underground stems which are enlarged to store food in form of carbohydrtes e.g. cocoyam, yam, irish potatoes
Vegetable Crops – Crops grown for their leaves of fruits. The leaves or fruits are eaten fresh or cooked. They supply mainly vitamins and minerals.
Fruits – Crops with succulent fruits which are eaten fresh. They can supply vitamins and minerals and sometimes carbohydrates. e.g are mango, banana, citrus, cashew, pawpaw
Beverages – they are crops whos products are used for making food drinks (bournvita and mila) or making non-alcoholic drinks. These crops are cocoa, coffee
Spices – these are crops used to add special taste or flavour to food e.g. castor, ginger, garlic
Oil Crops – These crops produce seeds or fruits from which we extract oil. They are the major source of oil used for cooking e.g groundnut oil, soya oil, shea butter, coconut oil
Fibre Crops – These are crops grown especially for their fibre. Fibres are used for making carpets, sacks, ropes. Fibres may be produced from stem or leaves or fruits and seeds. Examples are cotton, jute, kenaf, hemps, raffia.
Forage crops – These are crops grown mainly for feeding farm animals. Examples are elephant grass, guinea grass, centrosema, and some food crops such as millets, sorghum, cowpea and groundnut.
Latex Crops – These are crops whose stem or leaves produce sap which maybe used as gum or coagulated to form rubber. e.g gum arabica, para rubber
Drug Crops and Stimulants – Crops used for making medicines or for their stimulating effects. Examples are tobacco, cocaine, quinine, kolanut, eucalyptus
Ornamental Crops – Crops grown for purpose of making our environment beautiful e.g. barbados, lily, marigold, hibiscus, zinnia.
Classification Based on Food Nutrient
As source of carbohydrates – Yam, maize, Millet, cassava, potatoes
As source of protein – Beans, groundnut, soyabeans, pigeon peas
As source of fats and oil – castor oil, melon, palm tree, groundut
As source of minerals – Calcium. potassium, iodine, managanese, iron, sodium chloride are the examples of nutrients which can be supplied. example of such crops are fresh vegetables, apple, pineapple
As source of vitamins – Vegetables, orange, cabbage, carrot, soya beans
Assessment
Section A – Use the options below to answer the following questions
- Latex, Forage, Oil, Biennial, Perennial, Fibre, Spice, Cereal grain, Root, Halophyte, Drug, Ornamental, Ephemeral, Annual, Xerophyte, Tuber
- ____ crops complete their life cycle once in two years or two group seasons
- ____ crops are crops that complete their life cycle once in three or four months and can undergo two or three life cycles in a year
- _____ crops are crops whose stem or leaves produce sap which maybe used as gum or coagulated to form rubber
- _____ crops are underground stems which are enlarged to store food in form of carbohydrtes
- ____ crops are crops that produce seeds or fruits from which we extract oil.
- Any plant that lives more than 2years is a _____ crop
- ____ crops are grown for the purpose of making our environment beautiful
- ____ plant prefers salty soils
- _____ are crops used to add special taste or flavour to food
- ___ crops are used for making medicines or for thir stimulating effects
Section B – Categorise the following crops according to the options given below
Latex crop, Forage crop, Oil crop, Biennial crop, Perennial crop, Fibre crop, Spice , Cereal grain, Root crop, Halophyte, Drug crop, Ornamental crop, Ephemeral crop, Annual crop, Xerophyte, Tuber crop, Beverage,
- Mango
- Yam
- Ginger
- Shea butter
- Cocoa
- Hibiscus
- Quinine
- Carrot
- Maize
- Tomato
Section C
- Give 2 examples each of annual, biennial, perennial crops
- Give 2 examples of classifications of plant crops.