Back to: Botany 200 Level
Hello, my brilliant student! How are you today? Have you ever noticed how some plants survive long periods without rain while others dry up quickly? Plants that can survive with little water have special drought resistance mechanisms that help them avoid, tolerate, or recover from drought. Today, we’ll learn about the different ways plants resist drought and continue to grow even when water is scarce.
Mechanisms of Drought Resistance in Plants
Drought resistance refers to the ability of plants to survive and grow in dry conditions. Plants have developed three main strategies to cope with drought:
Drought Escape – Completing their life cycle before severe drought.
Drought Avoidance – Reducing water loss or improving water uptake.
Drought Tolerance – Surviving with very little water.
Let’s explore how these strategies work.
1. Drought Escape – Growing Fast to Avoid Drought
Some plants complete their entire life cycle before the dry season begins. This means they grow, flower, produce seeds, and die before water becomes scarce. Their seeds stay dormant until the next rainy season.
Example: Many desert plants, like some grasses, germinate and grow quickly after rainfall, producing seeds before the soil dries out again.
2. Drought Avoidance – Reducing Water Loss and Maximising Water Uptake
Plants that use drought avoidance survive by minimising water loss and improving water absorption. They do this in several ways:
Deep Root Systems – Some plants develop long roots that reach underground water. Example: Date palms and baobab trees.
Leaf Modifications – Some plants have small, thick, or wax-coated leaves that reduce water loss. Example: Aloe vera and cacti.
Closing Stomata – During hot periods, plants close their stomata to reduce transpiration. Example: Maize closes its stomata during midday.
Rolling or Folding Leaves – Some plants fold their leaves to reduce the surface exposed to the sun. Example: Rice plants during drought.
3. Drought Tolerance – Surviving with Very Little Water
Some plants adjust their internal functions to survive even with very little water. They use special methods such as:
Water Storage in Stems and Leaves – Succulent plants store water inside their thick stems or leaves. Example: Cacti and aloe vera.
Production of Protective Proteins – Some plants produce special proteins that help them survive drought. Example: Resurrection plants can lose almost all their water and still recover when water returns!
Efficient Photosynthesis – Some plants, like C4 and CAM plants, use special photosynthesis processes that save water. Example: Pineapples and agave plants.
Summary
Plants resist drought using three main strategies:
Drought Escape – Completing their life cycle before drought begins.
Drought Avoidance – Reducing water loss and absorbing more water through deep roots, waxy leaves, stomatal closure, and leaf rolling.
Drought Tolerance – Surviving with minimal water by storing water, producing protective proteins, and using efficient photosynthesis.
Evaluation
- What is drought resistance in plants?
- Name and explain one method of drought avoidance.
- How do succulents survive long periods without rain?
- Why do some plants close their stomata during the day?
Fantastic job! Now you know how plants survive even in the harshest dry conditions. Keep up the great work—Afrilearn is here to make learning fun and easy. See you in the next lesson!
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