Question

In water logged soil, plants generally are killed because of

• A. Deficiency of minerals
• B. Excessive absorption of water
• C. Absence of air in the soil
• D. Starvation

Answer 1

Answer: (C)

Absence of air in the soil

Soil particles have pore spaces between them. Waterlogging occurs when the soil is so wet that there is insufficient oxygen in the pore spaces present in the soil. The cells of the roots of the plants absorb oxygen from the water present in the soil for cellular respiration.

When the soil is well aerated, water in the soil can absorb oxygen from the air but when the soil is waterlogged, the air will diffuse slowly as there is low solubility of oxygen in the waterlogged soil.

So, the root cells don't get sufficient oxygen for cellular respiration and begin to die.

Another reason for the death of plants in waterlogged soils could be that when the oxygen availability is decreased, anaerobic conditions are created. This promotes the growth of anaerobic bacteria which release toxic substances that are harmful to the plant

So, the correct answer is 'Absence of air in the soil'