Environmental Factors – SS1 Horticulture and Crop Production Lesson Note (Second Term)

Nature’s Big Five

In Horticulture, we don’t just grow plants; we work with nature. Plants are living things, and just like you feel uncomfortable when it’s too hot or too dry, plants react to the environment around them.

The five “Big Bosses” of the environment are:

1. Light (The Energy)
2. Temperature (The Heat)
3. Rainfall (The Drink)
4. Wind (The Air in Motion)
5. Humidity (The Moisture in the Air)

If any of these five are out of balance, our tomatoes might not grow, or our flowers might refuse to bloom.

Light and Temperature

1. Light (Sunlight)

Plants use sunlight to cook their own food in a process called Photosynthesis. Without light, a plant will become pale, thin, and eventually die.

• Photoperiodism: This is a big word that just means “how long the sun shines.” Some plants (like Okra) need long hours of sun to flower, while others need shorter days.
• Intensity: Some plants, like Peppers, love the direct, bright sun. Others, like Ferns or young cocoa seedlings, prefer the shade.

2. Temperature (Heat)

Temperature tells the plant how fast to grow.

• High Temperature: Makes plants “sweat” (transpire) faster. If it’s too hot, the plant might wilt.
• Low Temperature: Can slow down the growth. In the cold parts of Nigeria like Jos, we can grow crops like Irish Potatoes that wouldn’t grow well in the heat of Lagos.

Rainfall (The Source of Life)

Rainfall is the most important factor for many Nigerian farmers. Water is the “bus” that carries nutrients from the soil up into the plant’s body.

• Amount: Some crops (like Rice) need a lot of water. Horticultural crops like Carrots need a steady amount—not too much, not too little.
• Distribution: It’s not just about how much rain falls, but how often. If it rains heavily for one week and then stays dry for a month, the plants will suffer.

Too much rain? It can wash away the soil (erosion) or drown the roots so they can’t breathe. Too little rain? The plants will dry up and die unless we use irrigation.

Wind and Humidity

4. Wind

Wind is simply moving air. It has both good and bad sides.

• The Good: It helps in Pollination (carrying pollen from one flower to another so fruits can grow). It also helps cool down the plant on a hot day.
• The Bad: Very strong winds can break the stems of tall plants like Maize or blow the flowers off fruit trees. It also makes the soil dry out faster.

5. Humidity

Humidity is the amount of “water vapor” (steam) in the air.

• High Humidity: Common in Southern Nigeria. It makes the air feel “heavy.” While plants stay hydrated, high humidity also helps Fungi and Diseases grow faster on the leaves.
• Low Humidity: Common during the Harmattan. The air is very dry, and it “sucks” water out of the plant leaves very quickly.

Summary and Human Control

As horticulturists, we cannot change the weather, but we can manage it! Here is how we handle these factors:

Final Thought for Students:

To be a great farmer, you must be a “Weather Watcher.” Before you plant, look at the sky, feel the wind, and touch the soil. Nature tells you what the plants need!