Mineral nutrition :mechanism of infection of plant

Mechanisms of infection of plants associated with mineral nutrition

To maximize potential productivity of the plants need throughout the growing period to control the growth and development of plants, as well as susceptibility to diseases and pests.

In order to assess the relationship of elements nutrition and plant health, one must understand how pathogens attack and reproduce in the plant.

Cycle all diseases consists of 3-4 parts, as shown in the figure. If all of the conditions the infection and spread of the disease. If any part is missing, the disease can be prevent or reduce the damage from it. Some pathogens, such as viruses, need the carriers for contact with the plant itself.

Vectors can be insects or fungi. If the activity of a carrier is interrupted, the disease can be controlled without direct impact on the pathogen. Nutrients and other mineral elements can influence all aspects of the development of diseases. Mineral elements affecting the environment. For example, the calcium effect on soil structure and the availability of other nutrients, is associated with exchange reactions of the soil complex and the reaction of the soil solution. Nutrients affect the ability of plants to resist weather conditions.

Fungal diseases

Fungal infection occurs when the plant surface germinate spores. As the germination, the fungus penetrates the surface (epidermal) layer of cells either by penetrating between the cells or through them. The physical resistance of the plant is the strength and integrity of cell walls and intercellular spaces – all this in the first line of defense plants. Nutrition plays a major role in the plant's ability to develop strong cell walls and other tissues (Si, K, Ca). The germination of spores is stimulated by substances secreted by the plant. The number and composition of these precipitates is affected by the power plant. When a certain plant food elements in a small quantity in the discharge will contain a lot of sugars and amino acids that contribute to the development of pathogenic fungi.

Once the fungi infect the plant, inside plant body starts the natural process of protection. Infection increases the production of inhibitors of mushroom phenolic components and flavono-

IDE like in the place of infection, and in other parts of the plant. Production and transportation of these substances is mainly controlled by plant nutrition. A deficiency of key nutrients (K, Si, Mn, Cu, Zn and b) reduces the amount of natural antigenic components in the plant in the place where the infection. Conversely, it was noted that the very large number of nitrogen or when there is an imbalance of nitrogen and other elements of food production antigenic substances in the plant is reduced. Once the fungi and bacteria penetrate the tissues, they secrete certain enzymes that dissolve plant tissue. The activity of these enzymes is inhibited by calcium ions (Ca2+). As soon as the pathogen secretes these enzymes that dissolve plant tissue from the plant starts to leave the potassium (K+). The loss of potassium reduces the ability of plants to resist disease for the reasons mentioned above.

Many pathogens penetrate the plant through open cuts (hail, pests), so a quick treatment of such wounds reduces the infection. Strawberries treated with large doses of potassium fertilizers, are less sensitive to the disease Botrytis cinerea. It happened because of the rapid healing and accumulation around wounds a large number of substances toxic to pathogenic fungi.

Another response of plants to infection is the formation of oxygen radicals (O2 - and OH-) and hydrogen peroxide (H2O2). These elements can be destructive for cells of the plant and the pathogen. This is very similar to the use of chemotherapy to treat cancer in humans. This treatment can also harm the patient. It is believed that in some cases it can cause the overproduction of such elements. In this case, some nutrients (Cu, Zn, Mn) act as detoxification oxygen radicals and hydrogen peroxide, thus limiting damage to plant.

Bacterial diseases

Bacterial diseases can be divided into 3 main types: mottling of leaves, soft rot and vascular diseases.

Pathogens causing mottling of the leaves usually penetrate leaves via stomata and spread in the intercellular space. As bacteria penetrate not through the leaf surface structure and strength of the epidermal layer does not really matter. Resistance of plants to bacterial spread within the leaf is closely connected with the structure and power of the inner cells and the intercellular space, as well as the ability of a plant to produce and transport antibacterial substances. This defence mechanism is closely associated with certain food elements Sa, b, and K.

The spread of bacteria in the plant is accompanied by the production of enzymes by bacteria that break down pectin (a primary structural component of cell walls). The production and activity of these enzymes is suppressed by some nutrients. Plants that have a shortage of these elements of nutrition necessary to build strong cell walls and other structural tissues will experience greater damage from these pathogens.

Bacterial vascular diseases spread in the xylem (channels that transport water and the nutrition elements from the roots to the leaves). The presence of bacteria in the xylem leads to the formation of "slime" inside the channels, which leads to blockage of channels and the withering away of the leaves and stems. Certain nutrients (K and P in the form of potassium phosphite) play an important role in blocking or reducing the activity of bacteria in the formation of this mucus.

Viral diseases

There is little information on the effect of mineral nutrition on viral diseases. Viruses live and reproduce inside the cells of plants, and their diet restricted in amino acids and nucleotides, which are located within the cells. Typically, nutrient conditions favorable for good plant growth are also favorable for the propagation of viruses. In some situations symptoms of viral diseases can be reduced or suppressed by improving plant nutrition. However, this does not mean that the virus will disappear, but will decrease its severity.

The main carriers of viruses are sucking insects such as aphids and fungi. Plant nutrition can affect the fungi and some insects and thus transferred their viruses. It was found that the nutritional status of plants can affect the number of aphids on it. For example, in 1965 it was discovered that aphids like to check in the yellow pages suffering from chlorosis due to the shortage of food. Feeding intensity and reproduction of sucking insects on higher plants, in which the higher the content of free amino acids due to the low activity of protein synthesis. These conditions are typical for plants that are experiencing some stress because of a violation of mineral nutrition. The introduction of elements such as silicon and potassium, physically and chemically inhibits the ability to feed sucking pests.

As sugar in the plant repels insects?

The only insect that migrates the high sugar content in the plant (above 10% or units) – this grasshopper. Other insects are unable to allocate the gas which is formed during the digestion of sugars and the consumption of large amounts of sugar, the insects die. A natural protection against death from such insects is the ability to feel the plants with a high sugar content and instinctively avoid them. In this case, the insects attack weaker plants with less sugar that they can digest. If with the help of mineral substances increases the quantity of sugars in plants up to 10 units of Brix or higher plants will be safe from most insects.

Balanced mineral nutrition throughout the growing period – a significant factor in increasing the resistance of plants to diseases and pests and reduce the pesticide load on plants to obtain organic fruits.

Stress and disease. A balanced diet is the prevention of disease

The reasons for the development and distribution.

Mineral elements affect crop yields not only improving the growth parameters and the formation of yield structure elements, but also by improving the immune status of plants, resistance to pathogens (ekologichna plant protection).

Plants with optimal nutritional status elements have the highest degree of resistance. When the deviation of the concentration of nutrition elements from this optimum increases the sensitivity of plants to diseases and adverse conditions.

Stress factors:

- Decrease in turgor of cells and tissues as a result of drought and high temperatures

- Violation of the intercession of the tissues as a result of mechanical damage or damage by pests

- Weakening of the immune system of plants during the adaptation of metabolism to unfavorable conditions

- Hormonal imbalance (increase in the concentration of ethylene and auxin reduction).

The imbalance of nutrition elements:

- An excess of nitrogen and deficiency of potassium, calcium lead to the formation of thin cell walls, through which the pathogens can easily penetrate

- Excess nitrogen lowers the pH of cell SAP, making it attractive for food pathogens

- A deficiency of potassium reduces the turgor of the cells and tissues

- Excess of free moisture in the cell arising from the shortage of K, Mo, Zn, si, etc., and the N surplus, improves conditions for the development of pathogens

- Deficiency of Zn, Mn, Cu, Fe, etc. disrupts the production of protective components of plant phytoalexins, flavonoids, coumarins etc.

A balanced diet is the prevention of disease.

1.Preventive measures – to achieve the economic Outlook of injuriousness (EPV) diseases: the balance of nutrients

- Use of basic fertilizers according to the results of soil analysis (N, P, K, Ca)

- Carrying out corrective foliar application at critical phases of development according to the results of functional diagnostics of plants

- Inclusion in the system of supply of fertilizers, contributing to the improvement of the immune status of plants under unfavorable weather forecasts – Kelik K-Si, Atlanta, Atlanta Plus, "Nutrivant Plus", etc. (increasing the strength of the cuticle of leaves, increase in the pH of cell SAP, the increasing share of associated (colloidal) moisture, restoring hormonal balance).

2. Upon reaching the EPV diseases: fungicide + fertilizer

- Reducing the number of pathogens

- The restoration of the physiological processes of plants

- Increase of resistance to stress factors and pathogens.

Stress and pests. Features correction of mineral nutrition to reduce the risk for pests

Pests, in addition to direct yield reductions due to damage of the tissues and organs of plants, serve as vectors of many viral and fungal infections weaken the immune system and create conditions for development of diseases.

The reasons for the settlement.

1. Stress factors:

- Decrease in turgor of cells and tissues as a result of drought and high temperatures

- Violation of the intercession of the tissues as a result of mechanical damage or diseases

- Weakening of the immune system of plants during the adaptation of metabolism to unfavorable conditions

- Hormonal imbalance (increase in the concentration of ethylene and auxin reduction).

2. The imbalance of nutrition elements:

- An excess of nitrogen and deficiency of potassium, calcium lead to the formation of thin cell walls that are easily damaged by pests

- Excess nitrogen lowers the pH of cell SAP, making it attractive to power-sucking pests

- A deficiency of potassium reduces the dry matter content in the cells, reduces the turgor of the cells and tissues

- Excess of free moisture in the cell arising from the shortage of K, Mo, Zn, si, etc., and the N surplus, improves the conditions of supply of pests.

Reducing the risks of damage from insects:

1.Preventive measures – to achieve the economic Outlook of injuriousness (EPV) diseases: nutrition balance

- Use of basic fertilizers according to the results of soil analysis.

- Carrying out corrective foliar application at critical phases of development according to the results of functional diagnostics of plants.

- Inclusion in the system of supply of fertilizers, contributing to the improvement of the immune status of plants under unfavorable weather forecasts – Kelik K-Si, Atlanta, Atlanta Plus, etc. (increasing the strength of the cuticle of leaves, increase in the pH of cell juice dry matter content, increasing share of associated (colloidal) moisture, restoring hormonal balance).

2. Upon reaching the EPV pests: insecticide + fertilizer

- Reducing the number of pests

- The restoration of the physiological processes of plants

- Increase of resistance to stress factors and pathogens.

*Preventive application of balanced nutrition reduces the pesticide load, in the later stages of ripening is preferable to apply immunoendocrine fertilizer (Atlanta, Atlanta Plus) that have no waiting period.

Method of determining stress. Functional diagnostics

Stress General nonspecific adaptive reaction of an organism to action of adverse factors. The internal manifestation of stress is accompanied by a slowdown of metabolic processes, changes in metabolism of the organism, the expenditure of energy for overcoming of negative factors of external environment at the expense of crop production.

Every time the plant is subjected to stress during the growing season, especially in the critical phases of development, reduced its productivity by 10-15%, and in some cases by 30-40%.

After exposure to stress factors – often have difficulty determining the cause of visual symptoms. Even experience does not always help to determine the cause of abnormalities in the development of plants and the method of its correction.

Visual stress symptoms are evident when internal violations have already occurred and are indicative of a deeper loss of genetic expression. When plants experience stress, they are unable to make the batteries, recycle and recover the body, which explains the unstable years, the returns from fertilizer use.

Under stress long before the manifestation of visual signs within the plant, the following changes occur:

1.The imbalance of mineral nutrients

2.The decrease in the intensity of photosynthesis

3.The protein hydrolysis into ammonium, destruction of chloroplasts and mitochondria

4.The increase in the concentration of ammonium to toxic levels and the production of ethylene (the aging hormone)

5.Reduced immunity to disease and pests.

At each of these stages is reduced photochemical activity of chloroplasts and manifests the so-called "hidden hunger". Due to the hidden metabolic disturbances inhibited the response of plants to fertilization, reduced the result of protective measures. The effectiveness of agricultural practices depends on the balanced mineral nutrition and activity of physiological processes.

If it fails to reveal "hidden hunger" of plants (before the symptoms of visual stress symptoms) and to help the plant overcome it, you can get the maximum potential productivity of the culture.

In this case indispensable are the rapid methods for the determination of pH, conductivity of the soil solution and the method of functional diagnostics of plants.

Method of functional diagnostics of plants are able to detect stress of plants long before the manifestation of visual symptoms of stress. It is based on the measurement of the photochemical activity of chloroplasts, which are the first to react to changing environmental conditions. Allows you to:

-Promptly (within 1 hour) to determine fiziologicheskoe the condition of the plants, to identify the imbalance of macro - and micronutrients, the possible loss of productivity.

-In a timely manner (day of analysis) to prevent loss through the use of anti-stress drugs, which are selected depending on the degree of stress.

-Choose a fertilizer for foliar application that best meets the needs of plants in specific soil and climatic conditions of the normal level of physiological processes.

The selection of fertilizers on the basis of functional diagnostics of plants takes into account the state of physiological and biochemical processes of plants and allows you to manage processes, we do not see, based on the knowledge of plant physiology. Revealing the hidden effects of adverse conditions, removal of plants from stress with the correct simultaneous dosed feeding allows you to maintain a balance of nutrients from germination to maturity, while maintaining yield and product quality.

Regular check-UPS - this is the "language of plants", which is necessary for understanding the internal problems of plants and timely decisions to overcome them.

On strawberries it is recommended to conduct functional diagnostics of plants in phase:

- growth of vegetative mass

- budding

- formation of berries.

Analysis of plant leaves should be accompanied by monitoring of salinity of soil and irrigation water (pH meter, Соmbo, etc.).

The organization of balanced mineral nutrition is stress management of plants

Basic fertilizer (ammonium, phosphate, potash) under the strawberries must be paid under the primary tillage (in autumn) or under preseeding cultivation (in spring) to prevent losses due to decomposition in air.

The introduction of full dose of fertilizers when planting creates an increased concentration of salts in the root zone and burn the root hairs, inhibits the growth of the root system and absorption of nutrients from the soil.

Various stress factors during the growing period, physiological processes of plants, significantly reduce the effectiveness of even very accurately calculated, taking into account all of the characteristics of the soil and the varietal characteristics of plants, doses of mineral fertilizers.

Reasons:

- Hormonal imbalance.

Consequences:

- Weak development of the root system

- The loss absorption capacity of roots

- A violation of physiological processes in the leaf tissue

- Reducing the transport function of phloem and xylem

- The redistribution of assimilates, survival by reducing the harvest.

To improve the application of basic fertilizers at varying soil and climatic conditions that create a stressful situation for plants and reduce absorption of food elements, there are special agricultural practices, corrective mineral nutrition at each stage of development:

1. Root feeding/ Fertigation.

2. Foliar application

FERTIGATION – 100% use of fertilizers

Fertigation is a method of fertilizing plants by supplying dissolved minerals in conjunction with irrigation water.

This technology was developed in the late 1960-ies and has been widely spread among agricultural producers around the world.

The introduction of fertigation was a natural and effective step in the development of agricultural technologies, and developed techniques and methods of applying fertilizers to feed the plants, allowed to successfully implement the system on irrigated areas using existing irrigation equipment.

The need for fertigation arose because traditional methods of making mineral fertilizers have only partial efficacy (rate of assimilation of nitrogen is 10-40%, phosphorus – 5-15%, potassium – 15-25%). The use of high doses of fertilizers for one introduction is often the cause of burns the roots, causing irreparable damage to the root system of plants.

On the other hand, if the granules of the fertilizers are in the soil at a considerable distance from the roots, the efficiency may be very weak.

The main disadvantage of the traditional fertilizer is the uneven distribution of fertilizers in the soil. If the fertilizer does not reach the tips of the roots and root hairs, it is not absorbed by the plant.

The supply of fertilizers with irrigation water allows more evenly distribute the batteries around the wetted layer.

Drip-hydrated layer of international relations is located in the zone of the main mass of roots, has horizontal and vertical dimensions, depending on soil type and dose of irrigation.

Fertigation allows to maintain in the soil the necessary level of concentration of nutrients on soils with low absorption capacity, nutrient poor, reduce the impact of adverse environmental conditions (lack of moisture, high temperature). Fertigation saves labor costs and energy for fertilizer application compared to traditional methods. In contrast to conventional irrigation, using large doses of irrigation water, allows not only efficient use of fertilizers, but also to prevent the contamination of groundwater, creates conditions for secondary soil salinization at the closing of the irrigation and groundwater.

Fertigation allows control of mineral nutrition of plants at each stage of growth and development of plants:

•Adjust the dose of fertilizer application depending on the physiological needs of plants in different growth stages

•Regulate the composition of fertilizers depending on the purpose and objectives of application

•To reduce the disadvantages of the various types of soils (weak pinning of substances on light soils with low absorbency, the formation of insoluble compounds with suboptimal pH, etc.)

•To reduce the risk of pollution of groundwater and the occurrence of secondary salinization

Is an indispensable agro – technology with the use of mulch and artificial substrates.

Types of fertigation:

•Open ground without mulch

•Open ground plastic mulch

•Indoor soil

•Artificial substrates

Foliar application

"The roots are the leaves located in the soil, leaves are roots in air"

A sufficient amount of nutrition elements in soil does not guarantee high productivity. Various biotic and abiotic stresses affect the availability of nutrients and poayday ability of the root system of plants.

Potassium and nitrate form of nitrogen can easily be washed out of the soil-you, the phosphorus is chemically bound with calcium and magnesium forming soluble compounds, etc. At low temperature slows down the consumption of food elements: phosphorus - at 10-11°C, nitrate – nitrogen at 5-6°C, potassium is at 7-8°C.

For the effective absorption of nutrients from the soil requires a high physiological activity of the plant. Photosynthesis and respiration provide the plant with energy to perform all physiological processes of consumption of nutrition elements from the soil and convert it into organic compounds, to maintain high viability of plants during the vegetation period and the yield formation. Adverse growing conditions (high or low temperatures, droughts, excessive rainfall, etc.) disrupt the hormonal balance of plants, reduce the intensity of physiological processes and the consumption of nutrients from the soil.

Therefore, to achieve high efficiency of application of fertilizers requires constant monitoring as the condition of the soil with the help of modern portable devices (Combo, PNT-3000, etc.) and the plant condition with the help of functional diagnostics of plants and timely correction of sheet feeding.

Foliar nutrition is the application used for quick correction of the imbalance of nutrients and increase consumption of nutrition elements by root system.

It is proved that the use of leaf feeding increases the consumption of nutrients from soil by 15-20%, and in some cases by 30% (Dr. Tukey).

By changing the concentration of elements in tissues by foliar application, the plant body, in an effort to balance the biological system, increases the consumption of nutrition elements by root system. This is called "pump effect".

Foliar application is the quickest way for the correction of mineral nutrition. It allows not only to preserve the foliage, but also to promote the development of new viable roots. The effectiveness of this way of food delivery in 5-20 times (on some items up to 100 times) shorter than the traditional power – through the root.

When a stressful situation when the root system is not able to absorb food – only sheet feeding can restore the physiological functions of plants and to normalize the exchange of substances with minimal loss of productivity.

Foliar application of fertilizers also affects hormone balance, which changes the direction of movement of nutrients and the physiological processes in the right direction. This is a unique opportunity to influence the growth and development of plants throughout the vegetation cycle, creating favorable conditions for the development of each structure element of the yield of strawberries.

Factors influencing the effectiveness of foliar feeding:

- structure of the epidermis

Waxy plaque pubescence impede the penetration of nutrients in the metabolic system of the plant. The inclusion of fertilizer Linocut, Rajkot, Razorman part feeding increases the efficiency of feeding.

- the ability of the elements to penetrate through the leaves

Phosphorus is the most difficult element to penetration through the leaves. Therefore, the inclusion in the composition of fertilizers Pertinant ("Nutrivant Plus"), or the inclusion of a phosphite-К2РО3 (Atlanta, Atlanta Plus) – increases the efficiency of correction of phosphorus nutrition.

- form elements

Water-soluble mineral salts are inferior in effectiveness of chelated forms of nutrients, low molecular weight amino acids penetrate cells much faster than the large humic molecules.

- the speed of biochemical processes in cells

If the plant is in distress and the activity of chloroplasts is very low, the items are very slowly absorbed and involved in metabolic processes.

High activity of chloroplasts, the efficiency of feeding increases several times.

- the quality of water for solution preparation (hardness, pH)

Increased water hardness affects the surface tension of the liquid and the emulsification and dispersion, may cause precipitation of some chemical elements and pesticides. Reaction (pH) of the solution affects the resistance of chemical elements and plant protection products, the availability of trace elements for plant nutrition. To improve buffermode solution apply such fertilizers as Linocut, Razorman, "Nutrivant Plus". For the acidification of the strongly alkaline water – Peracid, Nutrivant Drip.

the spreading uniformity of the spray working solution.

The volume of the working fluid, the type of the sprayer affect the achievement of the nutrition elements of leaf surface.