Question

SCIENTIFIC INQUIRY Cotton plants wilt within a few hours of flooding their roots. The flooding leads to low-oxygen conditions, increases in cytosolic Ca²⁺ concentration, and decreases in cytosolic pH. Suggest a hypothesis to explain how flooding leads to wilting.

Short answer

Plants growing in waterlogged soil may experience a reduction in water content, causing their leaves to wilt. The branching and growth in the soil enable the plant to absorb the water and minerals it requires.

The underground activity of soil and roots requires energy; thus, a high rate of respiration in roots causes the pores to obtain oxygen from the soil. Oxygen diffuses poorly, and an oxygen deficit soil causes waterlogging.

This deficiency of oxygen affects the root and, eventually, the whole plant. The plants thus growing in the flooded soil may lead to wilting in the leaves.

Step-by-step solution

Wilting

Wilting is a common condition in plants that occurs when there is a lack of oxygen in the roots, resulting in water loss in the leaves and the stem. The plant begins to wilt as the collapsing dried cells cannot hold the plant upright.

The wilting of plants can occur because of less water supply to the plants. The plants continuously lose water by transpiration, and if the water supply is less, the plants will lose all the water and wilt.

Flooding leads to low oxygen conditions

During flooding, low oxygen levels are common in root tissues, but they can also occur in shoot tissues when submerged in plants. Plants have a set of features that allow tissue aeration or altered metabolic activities even in the lack of oxygen.

As a result, one of the effects of low oxygen is a significant reduction in metabolism, which can drastically limit yield and, if left untreated for long enough, result in the death of a portion of the entire plant.

Flooding leads to wilting

Flooding would cause the cotton plant to wilt within a few hours, increasing the local water potential and quick water uptake by the surrounding roots. The quick influx of water, on the other hand, has a secondary effect, which is oxygen deprivation.

As a result, water removes all air from the surrounding area, leaving the roots with little or no oxygen. A decrease in the cellular pH is another indicator of anaerobic respiration, as this pH will be less than aerobic respiration.

So, the decrease in pH suggests that inefficient energy production is going on. Another indicator is the increase in calcium that indicates the loss of oxygen in the cells of the roots. Thus, it can be said that the roots oxygen depletion resulted in energy depletion.

Lower oxygen levels result in anaerobic respiration, which lowers energy, resulting in extreme stress or cell death of some root cells, preventing them from performing their water absorption tasks despite a vast supply of water, causing plant wilting.