Question

Which of the following is not a deficiency symptom of minerals? (a) Internode shortening (b) Necrosis (c) Chlorosis (d) Etiolation

Short answer

(d) Etiolation is not a deficiency symptom of minerals, as it is related to inadequate light exposure.

Step-by-step solution

Identify Deficiency Symptoms of Minerals

Understand that deficiency symptoms of minerals in plants typically include abnormalities related to growth, pigment formation, and cell and tissue integrity. Examples include internode shortening, necrosis, and chlorosis.

Understanding Symptom Terms

Becoming familiar with the terms: internode shortening refers to reduced distance between the nodes of a plant, necrosis refers to the death of plant tissue, chlorosis indicates a lack of chlorophyll usually resulting in yellowing leaves, and etiolation refers to the elongation of plants grown in partial or complete absence of light.

Determine the Non-Deficiency Symptom

Analyze each option and recognize that etiolation is not necessarily a symptom of mineral deficiency. It can occur due to inadequate light regardless of the mineral content.

Key concepts

Internode Shortening

Internode shortening in plants can be a clear indicator of nutritional stress, often linked to a deficiency in essential elements. Normally, internodes—the segments between the nodes of a stem—grow at a certain length to give a plant its structure and height. When plants lack specific minerals like phosphorus, zinc, or potassium, this growth is compromised, and the distance between successive nodes decreases. The effect can lead to stunted growth as the plant tries to conserve resources. This symptom not only affects plant aesthetics but also their ability to photosynthesize efficiently as leaves may become crowded, reducing light penetration and air circulation.

Consistent monitoring of plant height and node length can help in early detection of this issue. It's paramount to correct mineral imbalances promptly to ensure the return of healthy internode growth and overall plant vigor.

Necrosis

Necrosis signifies a serious condition in plants where cells and tissues die prematurely, which is often associated with deficiency in certain essential nutrients such as calcium, magnesium, or potassium. This cellular death results in brown, dried out patches on leaves, stems, or fruits. Unlike other deficiency symptoms, necrosis can quickly spread and become fatal if not addressed in time.

Plants require a delicate balance of nutrients to maintain cellular integrity and support various physiological processes. Without these minerals, cell walls weaken and membranes become porous, allowing pathogens easy access, further accelerating tissue death. Adequate soil testing, followed by soil amendment or foliar feedings, can prevent and treat necrosis, creating the conditions necessary for recovery and continuation of normal growth.

Chlorosis

Chlorosis is a common deficiency symptom in plants manifesting as a yellowing of the leaves due to insufficient chlorophyll production. Minerals like nitrogen, iron, magnesium, and sulfur are crucial for chlorophyll synthesis, and their lack can impede this process. The yellowing usually starts from the tips and edges of young leaves, slowly progressing inward, as these parts are the last to receive nutrients during shortages.

Chlorophyll is not only the pigment that gives plants their green color but also essential for photosynthesis, the process by which plants convert light energy into chemical energy. Thus, chlorosis not only hinders the aesthetic appeal of plants but also impacts their growth and productivity. By supplementing the deficient minerals, plants can usually recover their vibrant green color and their ability to conduct photosynthesis effectively.

Etiolation

Etiolation is a condition characterized by the elongation of plant stems, accompanied by a pale or yellowish color, and weak, underdeveloped leaves. This phenomenon occurs when plants grow in insufficient lighting conditions, which in turn prompts them to stretch towards the light source. The pale color is due to reduced chlorophyll production, as plants lack the energy needed from light to support normal pigment synthesis and growth. While etiolation can occur alongside mineral deficiencies, it is fundamentally a response to a lack of light, not directly caused by a lack of minerals.

Providing consistent and adequate lighting is the primary measure against etiolation. For indoor plants, gardeners may need to employ artificial lighting solutions to mimic natural light conditions. Sunlight is the best source for outdoor plants, so ensuring they are not shaded excessively can prevent etiolation. If etiolation has occurred, gradual reintroduction to proper lighting can help plants to recover and develop healthy, robust growth.