Copper

Copper (Cu) is a plant micronutrient and an important component of several enzymes and coenzymes involved in metablic pathways of plants. At high concentrations, Cu can become phytotoxic affecting plant development due to direct or indirect interference with numerous physiological processes. Cu may affect species differently and it can cause various effects depending on the plant growth stage at which the metal was applied, the concentration of Cu, and the duration of action. Copper accumulation in soils can be the result of natural soil properties, agricultural practices, like the use of Cu-containing fertilizers, organic residues, sewage sludges, fungicides and bactericides (Brun, Le Corff, and Maillet, 2003).

Copper can catalyze the formation of harmful free radicals, such as the hydroxyl and superoxide radicals (Sahu, and Mishra, 2004). Thus, the main effect of phytotoxic amounts of Cu is the induction of oxidative stress, which can cause changes in metabolic pathways as a defense mechanism that results in differential responses of enzymes in plant parts.Effect of Excess Copper on Tomato Plants: Growth Parameters, Enzyme Activities, Chlorophyll, and Mineral Content, Luisa Louro Martins and Miguel Pedro Mourato, Journal of Plant Nutrition 2006

Copper is essential for many plant functions. Some of them are

• It functions as a catalyst in photosynthesis and respiration.
• It is a constituent of several enzyme systems involved in building and converting amino acids to proteins.
• Copper is important in carbohydrate and protein metabolism.
• It is important to the formation of lignin in plant cell walls which contributes to the structural strength of the cells, and the plant.
• Copper also affects the flavor, the storageability, and the sugar content of fruits.

Factors Affecting Availability

• Root Growth: Copper is the most immobile micronutrient, therefore anything that inhibits new root growth will inhibit Cu uptake.
• Soil pH: Acid soils increase Cu uptake and High pH inhibits uptake.
• Organic Matter: Copper is readily and tightly complexed by organic matter, therefore high soil organic matter levels reduce Cu availability.
• Flooding: Waterlogged soils can reduce Cu availability while they are saturated, however after they are drained the Cu will become available again.
• Cu:Zn Balance: High Zn levels will reduce Cu availability.
• Cu:N Balance: High N uptake in the presence of marginal Cu levels can lead to a reduction of Cu transport into the growing tips of plants.
• Cu:P Balance: High soil and plant P levels can reduce Cu uptake due to reduced soil exploration by mycorrhizas associated with plant roots.
• N Stress: Low N availability decreases the vigor of plants to an extent that it may fail to take up adequate amounts of many other nutrients. Copper uptake can be affected in this way.

High Response Crops

While this is an essential element for all plants, these crops have been found to be especially responsive: alfalfa, barley, blueberry, beet, broccoli, carrot, cabbage, celery, eggplant, flax, lettuce, oats, onion, parsnip, pepper, rye, spinach, sudangrrass, tomato, watermelon, and wheat.

Copper toxicity

Source: www.scielo.br

Copper should not be applied to soils without a demonstrated need through soil and plant analysis. Toxic effects from over-application can last many years. Symptoms appear in young tissue and include; dark green leaves. Increasing the soil pH should also help reduce toxic effects, although this can cause deficiencies of other nutrients. In situations where toxic soil levels of Cu exist, the leaf analysis may not properly reflect the severity of the problem because the root damage can become self-limiting to Cu uptake.

Copper sulphate

sulfate can be used as a fertilizer or fungicide. It is commonly used by gardeners and commercial farmers to prevent problems Copper with fungus or mold.

Source: Physiol. vol.17 no.1 Londrina Jan./Mar. 2005

Effects on plants growth

Copper sulfate is used to supply crope in copper-deficient are as with the copper needed to flourish

Source: homeguides.sfgate.com

When copper sulfate is applied excessively, soil copper levels become toxic to plants. Plants growing in soil that has too much copper may develop discolored leaves as a result of iron chlorosis. Typically, leaves will become dark green, and then turn white as chlorophyll fails to enable proper photosynthesis. Additionally, copper toxicity can cause damage to the roots of plants. When roots are damaged, plants are likely to grow more slowly, wilt or even die.

Source: http://homeguides.sfgate.com

Using Copper in a Fertilizer Program

Soil testing is the first step in determining a need. Plant analyses are also useful, and when a need is determined treatment should follow.

Recommended rates of Cu
Method	Rate
Broadcast	1.0 to 10.0 lb./A
In-row	1.0 to 5.00 lb./A
Foliar	0.1 to 0.25 lb./A

Correcting problems is usually not difficult. Again proper liming must be considered as a basic step. Remember, excess Cu applications can easily damage plant roots and leaves, so proper application rates and methods are important. Soil applications of Copper materials can have an extremely long residual effect in the soil. Therefore, records must be kept on the total amounts applied to fields. If a foliar Cu product is "basic" in nature (the pH of the Copper product/carrier mixture is greater than 7.0), the potential for, and severity of foliar damage can be reduced. Good responses have been obtained from foliar applications of Copper-containing fungicides

Some Copper containing fertilizer materials
Product	Chemical Formula	Typical Cu %
Copper Sulfate Monohydrate	CuSO4iH2O	35%
Copper Sulfate Pentahydrate	CuSO4i5H2O	25%
Cupric Oxide	CuO	75%
Copper Chloride	CuCl2	17%
Copper Chelates	CuEDTA	8-13%

Source: hthttp://www.spectrumanalytic.com/support/library/ff/Cu_Basics.htm

Copper deficiency

Copper deficiency causes severe distortion and stunting of new growth. One of the most common examples of this deficiency occurs in Aglaonema commutatum Schott ‘Fransher.’ It’s leaves are distorted and dwarfed and sometimes have a hooked appearance, with the edges rolled upward toward the center. Terminal buds die, and laterals sometimes initiate growth, forming a witches’-broom.

Source: http://www.apsnet.org/publications/apsnetfeatures/Pages/Nutrients.aspx

Source: http://keys.lucidcentral.org/keys/sweetpotato/key/Sweetpotato Diagnotes

Copper in the environment

Copper can also enter the environment through waste dumps, domestic waste water, combustion of fossil fuels and wastes, wood production, phosphate fertilizer production, and natural sources (for example, windblown dust, from native soils, volcanoes, decaying vegetation, forest fires, and sea spray). Therefore, copper is widespread in the environment. About 1,400,000,000 pounds (640,000,000,000 grams) of copper were released in to the environment by industries in 2000. When copper is released into soil, it can become strongly attached to the organic material and other components (e.g., clay, sand, etc.) in the top layers of soil and may not move very far when it is released. When copper and copper compounds are released into water, the copper that dissolves can be carried in surface waters either in the form of copper compounds or as free copper or, more likely, copper bound to particles suspended in the water. Even though copper binds strongly to suspended particles and sediments, there is evidence to suggest that some water-soluble copper compounds do enter groundwater. Copper that enters water eventually collects in the sediments of rivers, lakes, and estuaries. Copper is carried on particles emitted from smelters and ore processing plants, and is then carried back to earth through gravity or in rain or snow. Copper is also carried into the air on windblown metallurgical dust. Indoor release of copper comes mainly from combustion processes (for example, kerosene heaters). Elemental copper does not break down in the environment.

Source: environmentalmicro.weebly.com