Plants and Their Deficiency Symptoms
Deficiency symptoms in plants are caused by bacterias or diseases and can also be caused due to the lack of necessary elements. These deficiency symptoms of necessary elements can be seen through different methods in plants. There is a mixture of different nutrients that plants need for their growth and to stay healthy. The nutrients required by plants in large amounts are called macronutrients. Examples of macronutrients are potassium, nitrogen, phosphorus, magnesium etc.
Nutrients required in small amounts are called micronutrients. Examples of micronutrients are copper, boron, iron etc.
Deficiency Symptoms for Macronutrients
There are many deficiency symptoms seen or observed in plants. Let us discuss them. Deficiency symptoms for macronutrients are as follows:-
1. Nitrogen:
We all know that protein is very important for all living organisms because it leads to healthy growth and development. Nitrogen is one of the significant elements required in protein. It also contributes 1% to 6% (approximately) of the plant#39;s dry matter. So nitrogen deficiency can easily be seen in the growth and development of plants. Yellowing is seen in stems and leaves.
2. Calcium:
Calcium plays a vital role in signaling and cell wall structure. Calcium deficiency affects the early growing leaves and the growth points of plants. Newly leaves seem to be hooked or distorted. Black spots may also appear near the mid leaf and the growth of plants may be stopped.
3. Magnesium:
It is the inner element present in chlorophyll and is also very important for plant metabolism. It also transports carbohydrates within the plant body. Yellow and dark spots are seen in the new growth of plants.
4. Potassium:
Potassium is a very important element for plants. It plays a very important role in the formation of starch, movement of sugar and pH stabilization. Deficiency of potassium leads to a sudden development of a tissue called necrotic tissue, due to which the leaves may appear to curl downwards.
5. Phosphorus:
Phosphorus is required by plants for photosynthesis and transpiration. These processes require energy in the form of Adenosine triphosphate (requires phosphorus). If plants lack phosphorus these processes will not perform well, the leaves also may become reddish-purple and the old leaves may turn black.
6. Sulfur:
Amino acids require protein synthesis which in turn require sulfur. The light green-yellow pigment can be seen due to the deficiency of sulfur which usually happens in early growing leaves.
Deficiency Symptoms for Micronutrients
There are also many deficiencies for Micronutrients. Earlier we discussed the deficiencies of micronutrients in plants and now let us move forward to the micronutrients:
1. Boron - The death of terminal buds might take place due to the lack of growth in plants.
2. Copper - Lack of growth in roots and stem might be observed.
3. Manganese - Due to this, the shoots, fruits and leaves might diminish in size and color.
4. Zinc - Purple pigmentation occurs along with veinal chlorosis.
5. Molybdenum - Leaves might turn yellow and they also might distort.
Test Your Knowledge
i. Which of the following comprise the elements that help to complete the lifecycle of plants?
(a) Essential elements.
(b) Non-essential elements.
(c) Macro element.
(d) Micro element.
ii. Who had put forward the concept of essential mineral nutrients required by plants?
(a) Carl Linnaeus.
(b) Arnon and Stout.
(c) Aristotle.
(d) Leonhart Fuchs.
Solutions
i. (a) Essential elements.
ii. (b) Arnon and Stout
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Do You know?
The most effective way to grow healthy plants is to improve the quality of the soil by adding compost or well-rotted manure. Spreading organic mulches around plants also enhances the quality of soil to a great extent. Nutritional problems can be addressed by keeping the soil depth at around 50 mm.
FAQs on Deficiency Symptoms in Plants
1. What are the main types of deficiency symptoms observed in plants?
When a plant lacks essential nutrients, it displays visible signs of distress. As per the CBSE syllabus, the primary types of deficiency symptoms are:
- Chlorosis: The loss of chlorophyll, which leads to the yellowing of leaves.
- Necrosis: The death of plant tissue, which appears as brown or black spots on leaves, stems, or flowers.
- Stunted Growth: The overall growth of the plant is severely reduced, resulting in smaller plants with shorter stems and smaller leaves.
- Premature Leaf and Flower Fall: Leaves and flowers drop from the plant earlier than they normally would.
- Inhibition of Cell Division: This can halt growth in specific areas like root tips or shoot tips.
2. What is the fundamental difference between macronutrients and micronutrients for plants?
The fundamental difference lies in the quantity required by the plant for healthy growth. Macronutrients are essential elements that plants need in relatively large amounts, typically greater than 10 mmole per kg of dry matter. Key examples include Nitrogen (N), Phosphorus (P), and Potassium (K). In contrast, micronutrients, or trace elements, are needed in very small quantities, usually less than 10 mmole per kg of dry matter. Examples include Iron (Fe), Manganese (Mn), and Boron (B).
3. What are the specific deficiency symptoms for nitrogen and phosphorus in plants?
Deficiency of nitrogen and phosphorus shows distinct symptoms.
- Nitrogen (N) Deficiency: The most common sign is chlorosis, or the yellowing of leaves. Since nitrogen is a mobile element, these symptoms first appear on older, lower leaves as the plant moves the available nitrogen to support new growth.
- Phosphorus (P) Deficiency: This often results in stunted growth and a distinct purplish or reddish discolouration on the leaves, especially older ones. It can also delay the plant's maturity.
4. Why do deficiency symptoms for mobile nutrients like nitrogen appear on older leaves first?
This happens because of the plant's internal resource allocation strategy. Mobile nutrients, such as Nitrogen (N), Phosphorus (P), and Potassium (K), can be transported from older, mature tissues to younger, actively growing parts of the plant where they are most needed. When a deficiency occurs, the plant sacrifices its older leaves by moving these essential nutrients to support the development of new leaves and buds. As a result, the deficiency symptoms like yellowing (chlorosis) are first visible on the older, lower leaves.
5. How can a student distinguish between the deficiency symptoms of iron and magnesium, since both cause chlorosis?
While both iron and magnesium deficiency cause chlorosis (yellowing), the key difference is the location and pattern of the yellowing. Magnesium (Mg) is a mobile element, so symptoms first appear on older, lower leaves. It typically shows as interveinal chlorosis, where the leaf veins remain green while the tissue between them turns yellow, sometimes in a striped or marbled pattern. In contrast, Iron (Fe) is an immobile element. Therefore, its deficiency symptoms appear on the youngest, upper leaves first, also as sharp interveinal chlorosis, because the plant cannot move iron from older tissues to new growth.
6. Why is it said that an excess of one mineral can cause a deficiency of another?
This phenomenon is known as mineral antagonism or toxicity. An excess concentration of one essential element can interfere with the uptake and utilisation of another. For example, an excess of manganese (Mn) can compete with both iron (Fe) and magnesium (Mg) for absorption by the plant's roots. It can also compete with magnesium for binding sites on certain enzymes. Consequently, even if iron and magnesium are present in the soil in sufficient amounts, the plant may show their deficiency symptoms, such as brown spots surrounded by chlorotic veins, due to the toxic levels of manganese.
