Factors Influencing Agriculture: Climatic Factors - Form 1 Agriculture Notes

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Climatic Factors(weather elements).

  • Rainfall,
  • Temperature,
  • Wind,
  • Relative humidity
  • Light.

Weather - Atmospheric conditions of a place at a given time period.

Climate - weather conditions of a place observed and recorded for a period of 30-40 years.


Supplies Water:

  • Which is necessary for the life process in plants and animals.
  • Which makes the plant turgid hence provides support.
  • Acts as a solvent for plant nutrients.
  • Cools the plant during transpiration.
  • Which is used as a raw material in photosynthesis.

When plants lack enough water they respond in different ways as follows:

  • By closing the stomata to restrict water loss.
  • Hastens maturity.
  • Some will roll their leaves.

Other plants have developed permanent adaptation to water stress such as:

  • Growing needle like leaves.
  • Develop fleshy leaves for water storage.
  • Develop long roots.
  • Wilting and death in extreme conditions.

Important Aspects of Rainfall:

Rainfall reliability;

- This is the dependency on the timing of the onset of the rains.

Amount of rainfall;

- Quantity of rain that falls in a given area within a given year.

Rainfall distribution ;

- The number of wet months in a year.

Rainfall intensity;

- Amount of rainfall that falls in an area within a period of 1 hour.


- This is the degree of hotness or coldness of a place measured in degrees Celsius.

- Cardinal range of temperature ¬ is the temperature required by plant to grow and thrive well.

- Optimum range of temperatures - the best temperature for the best performance of plants.

Effects of Temperatures on Crop Production:

Low temperatures:
  • Slow the growth rate of crops due to slowed photosynthesis and respiration.
  • High incidences of disease infection.
  • Improves quality of crops such as tea and pyrethrum.
High Temperatures

Increase evaporation rate leading to

  • Wilting.
  • Hastens the maturity of crops.
  • Increase disease and pest infection.
  • Improves quality of crops such as pineapples, oranges and pawpaws.


Wind is moving air.

Good effects of wind include:

  • Seed dispersal
  • Cooling of land
  • Pollination in crops
  • Brings rain bearing clouds

Negative effects of wind:

  • Increases the rate of evaporation of water.
  • Causes lodging of cereals and distorts perennial crops.
  • Increases evapo-transpiration.
  • Spreads diseases and pests.
  • Destroys farm structures.

Relative Humidity

- The amount of water vapour in the air

- Affects the rate of evapo-transpiration.

- Forms dew which supplies soil with moisture under dry conditions.

- High humidity induce rooting in cuttings.

- Increases disease multiplication and spread.


- Provide radiant energy harnessed by green plant for photosynthesis.

Important aspects of light:

Light intensity ;

- The strength with which light is harnessed by chlorophyll for photosynthesis.

Light duration;

- The period during which light is available to plants per day.

- Plant response to light duration is known as photoperiodism.

- Short-day plants - require less than 12 hours of daylight to flower and seed.

- Long-day plants - require more than 12 hours of daylight to flower and seed.

- Day-neutral plants require 12 hours of daylight to flower and seed.

Light wavelength;

- This is the distance between two - successive crests of a wavelength.

- It dictates the difference between natural and artificial light.

- Chlorophyll absorbs certain wavelengths of light.

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