Classification of Crop by Lifecycle – SS1 Horticulture and Crop Production Lesson Note (Third Term)

Crops are classified by life cycle into three groups: annuals (one year or less), biennials (two years) and perennials (more than two years).

Behavioural objectives

1. Define the life cycle of a crop.
2. Name the three groups of crops classified by life cycle.
3. Describe the features of annual, biennial and perennial crops.
4. Give Nigerian examples of each group.
5. State the advantages of annual and perennial crops to the farmer.

What is the life cycle of a crop?

The life cycle of a crop is the series of stages a plant passes through from germination of the seed to the production of new seeds.

• Germination: the seed sprouts and a young seedling appears.
• Vegetative growth: the plant grows roots, stems and leaves.
• Flowering: the plant produces flowers.
• Fruiting and seed production: the flowers form fruits that carry new seeds.
• Death or renewed growth: annuals and biennials die after seeding, while perennials keep growing.

Earlier lessons grouped crops by use (food crops, cash crops and so on). This lesson groups them by how long they live.

What are the types of crops by life cycle?

There are three types of crops by life cycle: annuals, biennials and perennials.

1. Annuals: complete the life cycle in one year or one growing season.
2. Biennials: need two years or two growing seasons.
3. Perennials: live for more than two years and fruit many times.

What are annual crops?

Annual crops are crops that complete their whole life cycle, from seed to seed, within one year or one growing season.

Features of annual crops

• Short life: they grow, flower, seed and die within one season.
• Replanting: the farmer must plant new seed or planting material every season.
• Quick harvest: food and money come back quickly.
• Soft stems: most are herbs with soft, non-woody stems.

Examples of annual crops in Nigeria

• Maize: the cob is harvested and the stalk dries up.
• Rice: grows fast in wet areas and is harvested in a few months.
• Cowpea (beans): completes its cycle in a short time.
• Groundnut, sorghum and millet: planted at the start of the rains and harvested the same year.
• Okra and tomato: vegetable crops grown from seed each season.
• Yam: new tubers are planted every season, so farmers grow it as an annual.

What are biennial crops?

Biennial crops are crops that need two years or two growing seasons to complete their life cycle.

Stages of a biennial crop

1. Year 1 (vegetative stage): the plant grows leaves and roots and stores food in its body.
2. Year 2 (reproductive stage): the plant uses the stored food to produce flowers and seeds, then dies.

Examples of biennial crops

• Carrot: the orange root forms in year 1 and flowers appear in year 2.
• Onion: the bulb is eaten in year 1, but seeds come in year 2.
• Cabbage: the head forms in year 1 and the plant flowers in year 2.

Farmers usually harvest biennials in the first year, when the part we eat is best. They keep a few plants into the second year only to get seeds.

What are perennial crops?

Perennial crops are crops that live for more than two years and flower and fruit many times without dying after each seeding.

Features of perennial crops

• Long life: some live for many decades.
• Repeated fruiting: they fruit season after season once mature.
• Woody growth: most are trees or shrubs, so they are called tree crops.
• Late first harvest: many take several years before the first harvest.

Examples of perennial crops in Nigeria

• Cocoa: gives pods for many years once it starts fruiting.
• Oil palm: source of palm oil and palm kernel.
• Rubber: tapped for latex for many years.
• Mango and orange: fruit trees that stay in the compound for generations.
• Cashew and kola: tree crops grown for nuts.
• Plantain: a perennial that keeps producing new suckers.

Advantages of perennial crops

• Planted once: the farmer does not replant every year.
• Steady income: they give harvests for many years.
• Soil protection: their roots and shade reduce erosion.

What is the difference between annual, biennial and perennial crops?

Annuals finish in one season, biennials in two seasons, and perennials continue for many years. The table compares them.

How can we remember the three groups?

Think of each group as a kind of work contract.

• Annuals: like a one-term contract.
• Biennials: like a two-term contract.
• Perennials: like a permanent job.

Evaluation

1. What is the life cycle of a crop?
2. Name the three groups of crops classified by life cycle.
3. Describe what happens in Year 1 and Year 2 of a biennial crop.
4. State two reasons why farmers like perennial crops.
5. Give two Nigerian examples each of annual and perennial crops.

Assignment

Draw and complete a table showing the lifespan, main characteristic and two examples of annual, biennial and perennial crops. Then explain in two sentences why a farmer who wants quick food and money may choose annual crops.