Micronutrients are essential for plant growth and play an important role in balanced crop nutrition. They include boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), zinc (Zn), nickel (Ni) and chloride (Cl). They are as important to plant nutrition as primary and secondary macronutrients, though plants don’t require as much of them. 

Some motives restricting the incidental additions of micronutrients include:

• High-yield crop demands remove micronutrients from the soil
• Increased use of high-evaluation NPK fertilizers containing less amount of micronutrient contaminants
• Advances in fertilizer technology minimize the residual addition of micronutrients.

      Plant growth and development can be retarded if any of those factors is lacking within the soil or isn’t properly balanced with other nutrients. A lack of any one of the micronutrients in the soil can limit growth, even when all other nutrients are present in adequate amounts.

Micronutrient Functions in Plants

• Most micronutrients are a part of the enzyme systems of plants.
• Micronutrients play vital roles in redox reactions
• Micronutrients play vital roles in photosynthesis.
• Micronutrients are vital in reactions including N fixation and Protein synthesis.
• Cl is basically concerned in osmotic and cation neutralization.
• Copper, Ferrous, and Molybdenum are active in the oxidation-reduction reactions in plants that are important for photosynthesis, and other metabolic processes.
• Fe is involved in chlorophyll synthesis and may be deficient in turf grass, particularly if soil is alkaline. Any circumstance that restricts root growth also can cause iron deficiency, for example, compaction.
• Zn and Mn are important for sure N transformations in plants.
• Ni is important for the feature of the urease enzyme.
• Mo is important for symbiotic fixation of N.
• B is involved in cell division, and seed formation.
• Co is important for the growth of symbiotic microorganisms, including rhizobia, free-living N-fixing bacteria

 

 

BORON

Boron (B) exists normally in soil  solutions as the BO₃⁻³ anion – the form normally taken up by plants. One of the most crucial micronutrients which  affects membrane stability, B helps the structural and functional integrity of plant cell  membranes. Boron-deficiency signs and symptoms first seem on the developing points, and certain soil kinds are greater at risk of boron deficiencies.

Boron is a crop element important for

• Sugar transport

• Formation of cell wall

• Production of amino acids

• Crop reproduction

• Flowering

• Fruiting

• Crop quality

Deficiency symptoms:

• Stunted growth of young crops

• The death of growing points

• Deformation of leaves

• Dark brown lesions on leaves

• Yellow chlorosis on leaves

• Poor flowering

When managing the quantities of boron, it’s important to keep in mind the fact that boron should be applied before the flowering crop stage. Application of boron during later stages is useless.

COPPER

Copper (Cu) turns on enzymes and catalyzes reactions in numerous plant- growth processes. The presence of copper is intently connected to Vitamin A production, and it enables a successful protein synthesis. Copper is needed for plenty of enzymatic activities in plants and for chlorophyll and seed production. Deficiency of copper can result in improved susceptibility to diseases like ergot, which can cause vast yield loss in small grains.

Deficiency symptoms:

• Chlorosis, wilting and drooping of mature leaves may be the first visible symptom of Cu deficiency.
• Poor plant growth, delayed flowering, and plant sterility.

IRON

Iron (Fe) is important for crop growth and food production. Plants take in Fe as  ferrous (Fe²⁺) cation. Iron is a part of many enzymes related to energy transfer, nitrogen reduction and fixation, and lignin formation.

The significance of iron is its function in chlorophyll production. For this reason, iron is the element important for photosynthesis and enzyme composition. Iron additionally affects the switch of energy, nitrogen reduction, and fixation, in addition to lignin formation. An iron deficiency causes yellowing among the veins on the younger leaves. Signs similar to the ones of N deficiency are expected. Such symptoms might consist of a popular pale green color, stunted growth with small leaf size, and viable reddening of veins on the young leaves.

Deficiency symptoms:

• Light green to yellow interveinal chlorosis on newly rising leaves and younger shoots.
• It is common to see shoots dying from the tip inwards.
• In extreme cases, newly emerged leaves might also additionally reduce in size and turn almost white, with necrotic spots.

MANGANESE

Manganese (Mn) features mainly as a part of enzyme structures in plants. It turns on numerous essential metabolic reactions and performs a direct role in photosynthesis. Manganese speeds up germination and adulthood at the same time increasing the availability of phosphorus (P) and calcium (Ca). The symptoms of a Manganese deficiency may easily be confused with a deficiency of Iron. These deficiencies manifest as the chlorosis or yellowing between the veins of young leaves.

However, when compared to an Iron deficiency, the transition between the leaf blade and the veins is much milder in a manganese deficiency. Manganese is needed with the aid of using plants for photosynthesis, breathing and enzyme reactions.

Deficiency symptoms:

• Newly rising leaves show off a diffused interveinal chlorosis with poorly described green regions around the veins. 
• Chlorosis and necrotic recognizing are common symptoms. 
• In severe deficiency, new leaves emerge as smaller and tip dieback can occur.

MOLYBDENUM

Molybdenum (Mo) is a trace element found in the soil, and is required for the synthesis and activity of the enzyme nitrate reductase.  For the process of symbiotic nitrogen (N) fixation by Rhizobia bacteria in legume root nodules Molybdenum is vital. Considering molybdenum’s importance in optimizing plant growth, it’s fortunate that Mo deficiencies are relatively rare in most agricultural cropping areas.

Molybdenum is an important component in  enzymes that convert nitrate into nitrite (a toxic form of nitrogen) after which it is used to synthesize amino acids within the plant. It is likewise needed through symbiotic nitrogen fixing bacteria in legumes to fix atmospheric nitrogen. Plants additionally use molybdenum to convert inorganic phosphorus into organic forms in the plant.

Deficiency symptoms:

• General faded green color
•  stunted growth with small leaf size 
• Possible reddening of veins at the young leaves.

ZINC

Plants take Zinc (Zn)  as  divalent Zn⁺² cation. It is one of the first micronutrients diagnosed as important for plants  and one most commonly limiting yields. Although Zn is needed simplest in small amounts, excessive yields are not possible without it.

zinc is a component of many enzymes. In addition to that, it is an important factor in:

• Early growth stages
• Root, seed, and fruit development
• Photosynthesis
• Balance of plant hormones
• Auxin activity.

Deficiency symptoms:

• Stunted growth
• Reduced length of internodes
• Smaller young leaves
• Yellowing on the lower leaves.

CHLORINE

Plants absorb chlorine (Cl) in the form of  chloride (Cl-) anion. It’s Active in energy reactions within the plant. Most Chlorine in soils results from salt trapped in determined materials, marine aerosols and emissions of volcanoes. Classified as a micronutrient, Cl- is needed by all plants in small quantities.

Chlorine is, indeed, a micronutrient required for plant growth, however important only in minute quantities. Because chlorine can kill bacteria, in immoderate quantities it is able to have a negative effect on the good soil bacteria that benefit plants. Excessive chlorine also can immediately injure plant roots.

Deficiency symptoms:

• Wilting of leaves particularly on the margins. 
• The leaves exhibit curling, bronzing, chlorosis, and necrosis, if the deficiency persist.

NICKEL

Nickel (Ni) was brought into the listing of essential plant nutrients in the past  twentieth century. Nickel is vital in plant N metabolism as it is part of the urease enzyme. urea conversion is impossible Without the presence of Ni. It is needed in very small amounts, with the important stage acting to be approximately 1.1 ppm.

Nickel has been shown to play a function in defense against a few plant diseases. Nickel is a component of a few plant enzymes, most notably urease, which metabolizes urea nitrogen into usable ammonia within the plant. Without nickel, toxic levels of urea can gather within the tissue forming necrotic lesions on the leaf tips

Deficiency symptoms:

• Chlorosis of younger leaves
• Reduced leaf size
• Less leaf growth. 
• One common Ni deficiency symptom across plant species is the necrosis of leaf tips because of the accumulation of urea to toxic concentrations