Why Do Plants Need Manganese? An Underrated Micronutrient (EDIT)

Like each of the 17 essential nutrients plants need, manganese has a vital role in plant growth. Though it’s required in small quantities, like other micronutrients, its presence is imperative.

Don’t judge its significance by the concentrations of manganese in plant tissues because the element’s contribution, no matter how small, can be the deciding factor between a failed and a successful crop.

Why do plants need manganese, and what can happen if they don’t absorb enough to cover their requirements? Continue reading, and you’ll learn all about the role of manganese in plant growth, symptoms of manganese deficiency, along with some practical advice to revive the plants.

What Is Manganese?

Manganese is one of the seven vital micronutrients required by plants to sustain their metabolic activities. Unfortunately, plants uptake it in amounts just less than iron, and people often confuse it with magnesium.

Both of them are essential elements for plant growth but play entirely different roles. Manganese deficiency is becoming widespread, posing several dangers for the plants.

What Is The Role Of Manganese In Plants?

So why do plants need manganese? We know that all plants absorb manganese, along with several other nutrients, but what exactly do they use this particular nutrient for? Let’s find out.

The element is involved in several biological processes going on inside the plant. The most distinct role is its contribution to the photosynthesis process. This is where manganese takes part in the water-splitting of photosystem II which gives electrons required during photosynthetic electron transport.

They’re also an essential cofactor in the oxygen-evolving complex that is a part of the reaction center protein of photosystem II. By activating certain enzymes, it’s also indirectly involved in the synthesis of chlorophyll.

Besides photosynthesis, Mn also shows its involvement in several other plant processes. For example, the formation of ATP molecules, fatty acids, lipids, and different proteins are also dependent on manganese absorbed by the plant.

It activates and acts as a cofactor for many enzymes involved in plant metabolism. Mn is also responsible for the elongation of root cells and protects the crops against root pathogens.

Hormone activation, photosynthesis, respiration, and synthesis of amino acids in plants will all suffer significantly if the growing medium lacks sufficient levels of manganese. Thus, manganese deficiency is a crucial problem that we can prevent by growing in rich, organic soil.

If you still diagnose the symptoms, make sure you address them before the plants become weaker and lose their productivity.

Manganese Concentrations Required By Plants

Mn deficiency appears when the element’s concentrations are lower than 20ppm in leaf tissues in most species. You will notice severe deficiency symptoms when the levels in plant tissue fall below 10ppm.

This means that healthy plants will have anywhere between 50 to 200 ppm Mn in their tissues. But, if you spray your plants with fungicides that include Mn, the element’s concentration can be much higher.

Mn toxicity, as you’ll later find out, is also harmful to plant health. Avoid using excess Mn fertilizers or fungicides to avoid any toxicity in plants. Mn concentrations higher than 1500ppm in plant tissues will cause the plant to show toxicity symptoms, depending on the surrounding temperature. Tolerance to high levels of manganese is generally higher at higher temperatures. In soil, Mn levels higher than 2000ppm are regarded as toxic to plants.

What Is Manganese Deficiency?

You’ve already seen how several plant processes depend on manganese coming in through the plant’s roots from the surrounding ground. If there isn’t enough Mn in the surrounding medium or the roots aren’t absorbing it in the preferred amounts, deficiency symptoms are unavoidable. So let’s see how a deficiency affects crops and how it is treated.

How Does Manganese Deficiency Occur?

Manganese deficiency is common in soils with high pH (alkaline soil). Soil with a pH greater than 6 is more prone to Mn deficiency than those with lower pH levels. Therefore, heavy application of lime to raise the pH levels can often result in manganese deficiency in the plants growing in the soil.

Sandy soils or soils that have been weathered over the seasons can also be low in manganese. A deficiency can get even worse if the climate is cool and wet. If the water for irrigation includes high bicarbonate levels, this can also hinder the plant’s manganese uptake.

Certain plant species are more susceptible to manganese deficiencies than others. These include legumes, cereal crops, citrus trees, potato, stone fruit trees, and canola. However, this doesn’t mean that other plants won’t show deficiency symptoms if growing in soil that’s low in the mineral.

Sometimes, competition with other minerals, present in more significant amounts, can reduce the plant’s manganese uptake. This is possible in soils that experience heavy fertilization. Overuse of fertilizers will often create an imbalance of nutrients, appearing as toxicity or deficiency.

What Are The Symptoms Of Manganese Deficiency In Plants?

So what does manganese deficiency look like? Since manganese mobility is low in plants, symptoms start appearing on the younger leaves during the disease’s initial stages.

Generally, it appears as the yellowing of leaves, accompanied by interveinal chlorosis. In cereal crops, pale patches on young leaves suggest that the plant lacks manganese. In tomatoes, the veins stay green, but the area between them turns yellow as the disease progresses.

Since several problems, including iron deficiency, magnesium deficiency, and nematodes, cause yellowing leaves, you cannot be sure if it’s manganese deficiency. The best option is to test the soil and plant tissue before applying any chemical fertilizers.

How To Fix Manganese Deficiency In Plants?

Get your garden soil tested, along with plant tissue samples, to see if it’s manganese deficiency that is affecting the plants or something else. Once you’re sure that a lack of manganese is causing the symptoms, there are many techniques to tackle the problem.

Generally, a complete micronutrient fertilizer is enough to solve the problem since Mn is only needed in small amounts by the plants. Magnesium sulfate can be applied as a foliar spray or as a soil amendment in case of severe deficiencies.

But, remember that excessive fertilization can do more bad than good. So, apply these in moderation, according to the package instructions, to avoid a nutrient burn.

1. Soil Application

Dilute manganese sulfate to half strength before applying it to the soil. ⅓ to ⅔ cups of manganese sulfate is enough for each one hundred square feet of land. Water the plants deeply before applying fertilizer to help the roots absorb the mineral faster.

2. Foliar Spray

In severe deficiencies, plants will respond faster to a foliar spray of manganese sulfate than soil applications. Therefore, prepare a diluted solution of the fertilizer before spraying it on the plants. Young plants respond best to foliar sprays. In the case of older plants or perennials, consider employing soil application.

Is Manganese Toxicity Possible?

High levels of manganese in the soil can be toxic to plants. Though it’s an essential micronutrient that plants won’t thrive without, when available in quantities much higher than the recommended range, it can cause problems.

While alkaline soils are prone to manganese deficiency, soils with pH levels lower than 5.5 are more likely to exhibit toxicity symptoms. Sometimes, excessive use of fertilizer can also create toxic levels of the element in the soil.

This is precisely why it’s essential to apply fertilizers in moderation, and only once you’re entirely sure which minerals are lacking in the ground. Geraniums, marigolds, New Guinea Impatiens are prone to manganese toxicity.

Burning of the leaf margins of older growth suggests manganese toxicity in plants. Brownish spots on older leaves can also be linked to the same problem.

Final Words

By now, you’ll have a clear idea of why do plants need manganese. After all, this post’s entire point is to educate gardeners on the significance of this trace element and protect their crops from suffering damage from manganese deficiency.

Rather than saving crops already exhibiting symptoms, the more effective approach is to feed them with a water-soluble complete fertilizer formula and do that constantly. It will keep them nourished with all the essential nutrients in their recommended amounts, preventing any deficiencies or toxicity.

Remember that plants suffering from a manganese deficiency aren’t a lost cause either. With prompt attention and the correct approach to fix the deficiency, you can revive your plants.

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