Soil and plant-based chloride (Cl) is almost always found in its Cl- form. It has a role in several physiological and metabolic processes in higher plants, making it a critical micronutrient. Osmotic and stomatal control, oxygen evolution in photosynthesis, and disease resistance and tolerance are just a few of their many roles in plant growth and development. When present in sufficient quantities, Cl increases the production and quality of several crops, including onions and cotton, when their soils lack this nutrient. On the other hand, cl is a primary contributor to salinity stress and may be hazardous to plants in high concentrations.
Chlorine's Relationship with Plants
Chlorine may not be the star micronutrient, but it plays a vital role in plant growth. Many species have sufficient chlorine levels for optimal growth. However, if concentrations drop below 70-700 μg/g d.w., this can lead to deficiency symptoms emerging and stunt development.
Sources of Chlorine
● Rainfall, sea spray, dirt, and air pollution are the principal natural sources of Cl in soils.
● Moreover, human activities like irrigation and fertilization also significantly contribute to Cl deposition.
● Cl deposition rates to soils vary from 1 to >1000 kg ha1 depending on geographic location and agricultural methods.
Role of Chloring in Plants
It's important to note that chlorine serves several purposes in the plant's physiology.
Osmoregulation Osmoregulation is the process by which an organism actively controls its osmotic pressure to keep its fluid and electrolyte levels stable. Osmotic pressure regulation is essential for carrying out metabolic processes and maintaining homeostasis. Plant and fungal cells' chemiosmotic regulation mechanisms differ notably from animal cells.
Stomatal Dilation Plants regulate gas flow through their tissues via biomechanical valves called stomata, which are holes on the surface of leaves. Guard cells line each stoma's edges and coordinate the stomata's opening and shutting.
Origin of Oxygen (O2) During Photosynthesis Photosynthesis is the primary mechanism for oxygen production in Earth's biosphere. This light-dependent process occurs in the chloroplasts of green plants, algae, and cyanobacteria.
Chloride reduces the impact of fungal diseases. As a result of chloride's antagonistic effects on nitrate absorption, ammonium nitrogen is preferred. Since excessive plant nitrates have been linked to disease severity, chloride's ability to reduce nitrate absorption may play a role in disease suppression.
Symptoms of Chlorine Deficiency
Cl deficiency symptoms include:
● Chlorotic leaves.
● Leaf spots.
● Brown edges.
● A confined and highly branching root system.
● Withering at the leaf margins.
● Leaf mottling when concentrations fall below the optimal range.
The effects of chlorine shortages have just lately started to be recorded. However, sandy soil in the interior might become chlorine deficient if excessive rainfall or plants are irrigated too regularly. Still, coastal soil is unlikely to be chlorine deficient (due to the massive levels of sodium chloride (salt) in the soil).
A lack of chlorine causes spotty chlorosis and necrosis on leaves. Distinct and abrupt borders between damaged and healthy tissue are characteristic of chlorine shortage in leaves, making it easy to tell apart from other nutrients' abnormalities. Bronzing or withering of leaves may occur in severe cases of chlorine shortage, albeit these signs are not dependable.
Fix Chlorine Deficiency
If your plants have a chlorine deficiency, you should ensure the soil is at a neutral pH of approximately 7. Then, incorporate any additional chlorine you may need (unless the affected plant requires special pH conditions). Maintaining optimal soil conditions is vital in enabling plants to grow and flourish. Make sure that your soil isn't too wet, dry, or compacted—plus add organic matter for an extra boost.
If your soil test reveals that it's deficient in chlorine, you can use chlorine-containing fertilizer to correct the problem. If your soil has low to moderate potassium levels, you may be able to use muriate of potash (potassium chloride or KCl) to boost the amount of chlorine and potassium in the soil; however, you should be careful not to end up with excess levels of potassium in the soil, so consult with a specialist fertilizer supplier for assistance if you need a custom fertilizer. To avoid harming your plants, you shouldn't use table salt (sodium chloride, NaCl) to boost chlorine levels in the soil.
Symptoms of Chlorine Toxicity
Scorching heat can sometimes take its toll on trees, leaving their leaves brown and withered. You might also find tissue bleached between the veins of a leaf or an unusual shrinking in size- even leading to yellowing and premature dropping off.
● It's possible that chlorine poisoning is to blame for the scorched leaves.
● Micronutrients, such as chlorine, are crucial to plant development. However, if chloroform accumulates in leaf tissue, the leaves will take on a burnt or burned look.
● The tips, edges, and spaces between the veins of the leaves of trees that have been burnt seem brown or lifeless. Instead of being burnt, leaf tissue may have a more bleached appearance.
● Leaves may be shorter than usual. They might prematurely turn yellow and fall off.
● Polluted air from chlorine gas or an overabundance of chloride in the soil can contribute to chlorination's hazardous effects.
How to Reduce Excess Chlorine?
● Gypsum is effective in lowering chloride concentrations. Mix 50 pounds of gypsum per 1,000 square feet of loam soil. Sandier soils require less gypsum, whereas heavier clay soils require more.
● Properly water the soil contaminated with chlorine to remove the toxicity.
Conclusion
Chlorine and chloride may sound similar, but they have drastically different implications for your crop's health. Chlorine is a powerful disinfectant to keep swimming pools clean and sanitary countertops. At the same time, chloride fertilization helps prevent disease in corn, millet, wheat, and barley- reducing root rot and tan spot, stripe rust, leaf rust & Septoria.
