Classwork Series And Exercises {Agriculture – JSS1}: CLASSIFICATION OF CROPS BASED ON LIFE CYCLE

Agriculture JSS1

Topic: CLASSIFICATION OF CROPS BASED ON LIFE CYCLE

Classification of Crops based on Life cycle and Uses

Crops plants are classified based on three criteria which are;

1. Botanical classification – Based on generic and specific names
2. Agricultural classification – Based on the uses or important of crops to man and animals
3. 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 or 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

 Exercise

Give 2 examples each of annual, biennial, perennial crops

Give 2 examples of classifications of plant crops.

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