Plants may need manganese in small quantities, yet it is packed with powerful potential. This essential nutrient plays a crucial role in photosynthesis and other physiological processes within plants; who knew Mn could have such a significant impact?
Unfortunately, deficiencies are not uncommon - especially on sandy soils or tropical climates that experience wetter conditions. Various crops appear to suffer from this deficiency, including wheat, legumes like common beans & peas, stone fruits, palm trees, citrus fruit & potatoes! Thankfully, all hope isn't lost, as studies have found that fertilizing can help revive these foods to their peak performance!
Role of manganese in agricultural production
At all stages of plant development, manganese is required for photosynthesis. In addition, manganese serves as an enzyme activator, aiding the crop in converting nitrate (a type of nitrogen) into a form the plant can use. Furthermore, manganese aids iron in producing chlorophyll.
As an essential component of the photosystem II-water oxidizing system, manganese plays a crucial part in photosynthesis. As Mn aids in the photolysis (light splitting) of water molecules, it supplies energy for photosynthesis and is essential in this system.
Thus, it should be no surprise that a severe impairment in photosynthesis occurs even without visible leaf symptoms due to Mn shortage. Significant reductions in soluble sugar concentrations occur throughout the plant as a direct consequence of the Mn deficit in photosynthesis. In addition, dry matter production and production decreases under Mn-deficient circumstances, which is often attributed to a decrease in photosynthesis.
Synthesis of Lignin
Several enzymes that catalyze stages in the formation of lignin and phytoalexins rely on Mn as a cofactor. Since lignin acts as a shield against pathogenic infection, its impaired production in Mn-deficient plants, particularly in the roots, is linked to an increase in pathogenic attack, notably from soil-born fungus. Applying manganese helps crops fight fungal leaf diseases, including tan blotch in wheat, powdery mildew in grapes, and black leaf mould in tomatoes, in addition to a wide range of soil-borne conditions like take-all in wheat, widespread scab in potatoes, and root rot in cotton.
Enzyme Peroxidase
Another enzyme that helps resist pathogens is peroxidase, which produces hydrogen peroxide. The created hydrogen peroxide is a fungicide that helps stabilize the cell wall. This is because it is immediately harmful to pathogens.
Ability to Deal with Stress
All other environmental stress types may be considered oxidative stress because manganese plays a vital role in enhancing stress tolerance. Because superoxide dismutase enzymes, which are responsible for detoxifying harmful free radicals, need several metal cofactors, including Mn, to operate. The rise in Mn-superoxide dismutase activity has been linked to improved winter hardiness, ozone tolerance, salt resistance, and drought resistance in plants.
Causes of low manganese levels
Although manganese is naturally present in the soil, it is sometimes bound or fixed in the ground in a way that prevents it from being absorbed by plants. A manganese deficit may result from or be exacerbated by the following conditions.
● Sandier, coarser soils have a higher risk of manganese deficiency because the element is more likely to be washed away from the plant's root system.
● High soil organic matter levels may restrict manganese availability because of the element's interaction with organic molecules.
● Increased manganese deficiency is predicted for severely worn soils with a pH greater than 6.
● Cool, damp weather may reduce the amount of manganese in the soil, negatively affecting agricultural yields.
● Manganese deficiency is often seen in low regions in a field with mucky conditions, and its effects are not uniform.
How to spot Manganese deficiencies?
Crop output suffers from manganese insufficiency, which is sometimes misunderstood as a nitrogen shortfall. Because of this, it is even more critical to detect the signs of manganese shortage so that we do not underestimate the effect manganese insufficiency may have on a crop and its production potential. Possible manifestations of these symptoms include:
● Chlorosis of the interveinal spaces in immature leaves
● Manganese deficits, in contrast to nitrogen shortages, manifest in younger leaves.
● Upper leaves with yellowish streaks
● Infections can cause the development of grey specks (oats), white interveinal stripes (wheat), or brown interveinal stripes and spots (barley)
● Soybean leaves turn from light green to pale yellow in two stages. When the shortage is severe enough, brown and lifeless spots are formed.
Due to manganese's poor phloem movement in plants, signs of Mn deficiency often appear in younger leaves first. For Mn shortage to occur, immature leaves must be below 20 ppm. Therefore, pale mottled leaves are the first symptom of manganese deficiency in dicot plants, followed by the more usual interveinal chlorosis.
Dicots, too, may have a brownish spotty appearance from Mn shortage. Cereals might show symptoms of Mn shortage in light green or yellow spots on younger leaves. Necrotic patches on older leaves characterize grey specks.
Methods for Treating Manganese Deficiency in Plants
Optimal root manganese absorption occurs in the pH range of 6.0 to 7.0. The optimal pH range for cannabis plants is 6.0 to 6.5. Hydroponically grown plants do best with a pH between 5.5 and 6.5, while a level below 6.0 is ideal for maximum absorption. The system must be flooded with nutrients, pH water, and manganese to correct a manganese shortage in plants.
After removing excess nutritional salts and iron, the root system is again balanced and may absorb manganese. Therefore, the treatment of manganese deficiency with manganese sulfate is successful. If the sand contains limestone, the wetlands are marl-based and alkaline, or plenty of lime has been spread, you should apply manganese sulfate.
Conclusion
Fertilizing for prevention and correction of Mn deficiency can have tremendous benefits, from better photosynthesis to stronger plant resistance. The result? Higher yields without additional fungicides or stress tolerance solutions like drought aid.
Keeping an eye on your plants is vital to ensuring they reach their full potential. After treating a manganese deficiency, you should notice improvements within seven days. If yellow or brown spots have already spread across the leaves before treatment, don't fret - unfortunately, those affected areas will not recover and turn green again! Keeping vigilant ensures that any issues can be remedied promptly, so your plants grow strong and healthy!
