MOST COMMON PHYSIOLOGICAL DISORDERS OF TOMATO

Hello friends of the farm in this opportunity I will talk about the physiological disorders of tomato cultivation also called abiotic diseases, since it has its origin in a complex interaction of genetic and environmental factors which cause a series of anomalies to different structures of the plant, generally due to adverse weather conditions or nutritional deficiencies, and the understanding of environmental and endogenous factors that influence such disorders could help reduce or eliminate its incidence and also reduce the yield of marketable fruits.

BETWEEN THE MOST COMMON PHYSIOLOGICAL DISORDERS IN TOMATO CULTURE ARE INCLUDED:

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APICAL PUDRICIÓN DEL FRUTO OR CULILLO
It is characterized by the presence of a white watery area at the apical end of the green fruits. As this area dries out, it becomes a dark-brown, leathery texture stain. It usually occurs early in the season when the load of fruits is low.
One of the most common nutritional disorders of tomato production under greenhouse, and is caused by calcium deficiency in the plant. This physiological disorder occurs in green and mature fruits manifested as a necrosis or rot in the apical part of the fruit and deteriorates its quality.
Typical damage in fruit due to a calcium deficiency To prevent this disorder some preventive measures can be taken, such as: liming the soil to raise the pH and increase the availability of calcium, maintain a good level of calcium in the nutrient solution, avoid stress of water in the soil, either due to deficit or excess, to prevent both high relative humidity and low humidity within the crop, to use varieties that tolerate little calcium in the soil and to apply foliar applications at the time of flowering with products based on calcium, such as nitrate or calcium chloride.

Corrective measures
Use less vulnerable varieties.
Facilitate the intake of water by maintaining uniform and adequate moisture in the root zone, not too wet or dry, nor too high in the nutrient solution.
Avoid values ​​of VPD and temperature too high or low during the day to favor the movement of water to the fruits.
Avoid very high concentrations of K and Mg, as this reduces the intake and availability of Ca.
The excessive fertilization with N can also lead to apical rot, since it favors an excessive vegetative growth, which extends the transpiration surface and prevents the transport of Ca and its accumulation in the fruits. It is known that reducing the proportion of leaves to fruits (clearing) and avoiding high temperatures and low concentration of oxygen in the roots can also reduce the incidence of apical rot.

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FRUIT CRACKING
The cracking of the fruit is characterized by the presence of cracks of different depth and shape, while the radial cracking presents cracks in the form of a star from the interior of the calyx along the cuticle of the fruit. The causes are similar in both cases and occur in fruits developed and in the process of maturation.
Cracking of the fruit is a complex disorder, associated with a sudden increase in the size of the fruit due to the rapid net inflow of water in the fruit, which causes the skin to expand beyond its elastic limit.
Cracks in fruits are presented for the following reasons:
High concentrations of sugar and soluble solids generate lower osmotic potential in the fruit than in other parts of the plant; this promotes the circulation of water within the fruit forming cracks; This cause is common in cherry tomatoes.
There are three types of cracking in the fruits:

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THE RADIAL CRACKS that develop from the chalice of the fruit towards the apical part of it;

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CONCENTRIC CRACKS are presented around the chalice and have a circle or semicircle shape,

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DIMINUTE CRACKS small cracks that develop around the shoulders of the fruit, of uneven appearance and present in large quantities.
In tomatoes that are exposed to direct sunlight mainly due to loss of foliage.
• Low levels of nutrients especially potassium, calcium and magnesium, which are essential for the construction and strengthening of the cell wall.
• Strong pruning of leaves that results in reduced evaporation and loss of fruit protection, which increases cracking due to root pressure.
• Old plants with little leaf area and scarce vegetation, or damaged or defective leaves, limit evaporation through the foliage, and this can result in cracked fruits due to the excess water they reach.
• Virosis appearance, especially YLCV.
• High humidity that limits evaporation through the foliage and creates water stress causing cracking.
• Sensitive varieties.
• Adequate fertilization with calcium, magnesium and potassium to strengthen the cell wall and, thus, encourage a resistance of the fruit to cracking.

Corrective measures. To reduce or prevent cracks in the fruits, varieties tolerant to cracking should be used, maintain constant soil moisture, avoid planting in times of high temperatures and solar radiation, avoid accidental irrigation or rain, maintain adequate nutrition with potassium, calcium and magnesium and protect plants from diseases and pests that damage vegetation A combination of crop management practices, greenhouse temperature and irrigation strategies should be employed. Among cultivation management practices we cite the maintenance of a slow but steady fruit growth rate, the reduction of the leaf / fruit ratio and the installation of shading screens to avoid too high temperatures in the fruit.
Harvesting before the pink stage contributes to the reduction of fruit cracking. It is advisable to gradually increase the air temperature of the night a day, as well as to keep the difference between day and night temperatures to a minimum to reduce the period of fruit ripening.
The most important type of control is based on irrigation management, especially in greenhouses that lack strict control of air temperature or the ability to gradually increase the temperature. Each morning, the plants should use the water available in the block before the first irrigation session takes place.
With regard to nutrition, it is important to provide plenty of calcium to strengthen the division and integrity of the cell wall.
The cracking of the fruit is an inherited tendency, so different varieties have different susceptibility to the disorder. If this problem exists in your region, contact several seedbeds and ask for a variety less vulnerable to this disorder.

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RAIN OR EPIDERMAL HERRUMBRE
The rust of the fruit is characterized by the presence of multiple micro cracks in the skin of the tomato, also called cracking of the cuticle, reduces the shelf life, and could lead to dark shoulders due to the loss of water. This deteriorates the appearance of the fruit and reduces the percentage of marketable fruits.
The combination of a sequence of high and low expansion rates with low elasticity of the epidermis of the fruit is the cause of the rust. The contraction / expansion cycles of the fruit skin are the result of high water stress at noon followed by high pressure on the roots at the end of the day. Excessively low night temperatures lead to condensation of water on the skin of fruits whose temperature is higher than the surrounding air, which also leads to rust.
Corrective measures. Rust control is similar to controlling the cracking of the fruit. It is important to prevent excessively low air temperatures (15 to 18 ° C is ideal), depending on the daytime radiation levels.

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MALFORMATIONS (CAREGATO)
It is a common disorder in greenhouse crops. It occurs due to the presence of high relative humidity and low temperatures, which implies reducing the viability and the amount of pollen; Both the ovary and the stamens are distorted and the fruit is deformed , accompanied by a corky tissue in the cavities that form; the previous thing causes that this type of fruits are rejected in the market
Maintain healthy cultivation, mainly of mildew, foliar molds that significantly reduce the evaporation surface of the foliage.
Adequate fertilization to promote a continuous growth of healthy foliage, which allows transpiration and evaporation of the water absorbed by the roots.
Avoid a severe pruning to the plants in order not to reduce the rate of vegetative evaporation and then reduce the water stress on the fruit.
When temperatures are very low, especially on very cloudy days, it is necessary to irrigate with very little water to prevent excess and moisture accumulation, which could be absorbed by the roots of the plant, which creates pressure on the fruit and cause cracking.
Extreme drought of the soil followed by the application of a large volume of water causes the fruit to crack; It is important to maintain a regular fertigation routine and a uniform level of moisture in the soil.
Measures to reduce cracking

Fruits with malformations. Face of cat For its control it is necessary to look for to diminish the low temperatures and high humidities within the greenhouse; for this, humidity and temperature measurements are made at different times of day and night and the decision is made to open or close the greenhouse curtains.

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FALL OF FLOWERS
This occurs when the relative humidity of the greenhouse is below 60%; It also occurs when the plant is exposed to winds, which prevents normal pollination of the flower; the pollen dries up and causes its abortion. It also occurs due to a deficiency of boron in the plant, especially during the flowering season, when excessive applications of nitrogen are made and due to the presence of diseases such as gray mold or Botrytis cinerea Figure 207. Abortion of flowers in the inflorescence

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MATURE RIPPENING (BLOTCHY RIPPENING)
It is characterized by an irregular maturation in the fruit because in some areas not enough lycopene accumulates to produce a homogeneously red fruit. It is a loss of color in certain areas of the fruit during the maturation process. The most frequent causes are associated with an inadequate nutrition plan, ingestion of insects that feed on the plant, fruit temperatures above 30 ° C due to excessive radiation and low air temperatures. Some areas do not acquire the characteristic red color but form tanned colorations; the spots are not uniform in shape or size, and extend to cover a large surface of the fruit. Generally the immature areas have greater hardness than the red areas.
For your control,
It can be mitigated by using resistant varieties, avoiding sudden fluctuations in the greenhouse environment, maintaining air temperature below 30 ° C, avoiding exposure of the fruit to direct radiation, avoiding severe defoliation, and providing 20% ​​extra K from the previous two weeks to the first harvest, until a week after this one.
It is also convenient to avoid that the harvest season coincides with the period of high cloudiness; try to increase temperatures in the greenhouse at night time; ventilate the greenhouse to prevent the accumulation of excess moisture around the clusters; avoid high population densities, which reduce or prevent the passage of air and light between plants; remove leaves from plants to allow the penetration of light into their bases; apply higher amounts of potassium, and maintain the nitrogen potassium ratio of 1: 2 in the soil. And finally avoid sensitive varieties to Blotchy rippening

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ROLLED SHEET
This disorder is characterized by an upward or downward twisting of the leaves. The curling up occurs because the plant is subjected to extreme conditions of stress, high or low temperatures, or water. The coiling down is produced by exposure to direct radiation from the sun on the plant. The leaves become brittle and brittle. Plants with rolled leaves have low rat photosynthesis and transpiration, which significantly reduces production. When the curl of the leaves is severe, the fruits are exposed to extreme temperature conditions, and the susceptibility of the fruit to cracking and at different levels of sunburn is increased, and its firmness can still be damaged. The leaves remain turgid but do not wilt. The growth of the plant is not affected and the formation of fruits is normal.
Leaf rolled up by stress conditions in the plant
Leaf rolled down by high solar radiation

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LOSS OF GROWTH POINT OR MALE PLANT
When plants of indeterminate growth stop the growth point for unknown reasons, an inflorescence or a leaf appears in the crown similar to what happens at the end of the growth point in certain varieties. It is very common in the field, when the plants have a dense vegetation, a thin stem and large leaves, as a result of uncontrolled fertilization and irrigation
Plants that lost their growth point The disappearance of the growth point can occur both in the nursery and in the first days of the transplant, or after the normal appearance of the 5th or 6th inflorescence in the plant, and it appears only in a small percentage of the crop. In certain cases, the cessation of growth is total, while in other cases a new secondary branch grows to replace the growth point.

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HOLLOW FRUITS
This disorder in the plant is caused by the excessive use of nitrogen in the application of fertilizers, the excess of hormones for the curd of the fruit, the low solar radiation, a bad pollination and the use of varieties sensitive to this disorder. For these same conditions can also form triangular fruits, which do not have the same characteristics of the variety. The hollow fruits have a cavity or hollow between the wall of the fruit and the placenta that contains the seeds, which gives loss of firmness to the fruit and shortens its useful life
Hollow Fruits To control this disorder in the plant, the entrance of light to the greenhouse must be improved, cleaning the plastics in the event that they have a great accumulation of dirt, sowing at opportune times so that the high luminosity coincides with the time of harvest, favoring pollination with inflorescence vibration techniques, avoid excessive nitrogen fertilization and high population densities, and prune the leaves that prevent the penetration of light into the fruits, avoiding likewise severe pruning.

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EDEMA
It is characterized by green protuberances like calluses on the upper and lower surfaces of the leaf. These protuberances can break as they grow. . Edema by saturation of water in the leaves This alteration develops when the tissue of the leaf is saturated with water, as a result of a pressure exerted by the root to continue carrying the water to the plant when the perspiration is poor. Generally, this happens when the soil is warm and humid and the air temperature is cool, combination of high humidity and low temperature. The prolonged periods of humidity favor this alteration. The incidence of this alteration is reduced by maintaining adequate ventilation for greenhouse crops and soil moisture levels.

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FRUIT WITH SPIRITS TYPE ZIPPER
There are thin tanned scars that go from the calyx of the fruit to its base in different lengths, caused by a problem of bad pollination, since at the time of forming the fruit the anthers remain attached to the wall of the ovary. Disorder appears when there are extreme temperatures (high or low) and excess humidity in the greenhouse. Some varieties are more sensitive than others. Fruits with zipper grooves

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GOLDEN STAIN
It is formed through small irregular freckles of green color in the chalice and shoulders of ripe fruits, reducing the visual quality of the fruit and its shelf life. This usually happens in the summer. The cells associated with the golden spot contain calcium salt crystals.
Causes. It includes excess calcium in the fruit associated with low DPV (high HR) and high proportions of K / Ca. The temperatures of the air excessively high in average also favor their formation.
Corrective measures
Avoid vulnerable varieties.
Increase EC slightly in the nutrient solution by increasing the K / Ca and Mg ratio, which reduce the risk of an excess in Ca intake.
Reduce content in Ca from 200 to 120 mg / L reduces the risk of golden spot and prevents apical rot.

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SUNSHINE
It is produced by a direct exposure of the fruit to the sun's rays, which generates a shiny and leathery white area. It originates when strong prunings of leaves are made that leave the fruit uncovered, which suddenly increases the temperature of the fruit and causes damage. in the tissue. Fruit with sunburn The use of varieties resistant to wilting and foliar diseases can reduce sunburn losses. Losses can also be reduced by carefully harvesting and pruning the crops to reduce defoliation and direct exposure of the fruit to sunlight.

THE CONCLUSION:
Plants can be subject to numerous types of environmental stress. Drought, extreme temperatures and excess light are environmental factors that can affect the development and quality of plants which is very difficult to control in outdoor crops, and although the greenhouses soften the effects of these factors, they can not be completely eliminated . It could also be said that the factors causing stress in the plants derived from the cultivation practices are usually given in specific crops of a certain plant, in a place and with a defined objective. Cultivation practices are designed to stimulate and maintain the growth and development of a plant, however, they can also cause abiotic problems.

SOURCE:
http://www.canna.es/los_desordenes_fisiologicos_en_las_plantas
https://es.slideshare.net/linneohco/desordenes-fisiologicos-y-nutricionales-en-tomate
https://www.hortalizas.com/proteccion-de-cultivos/como-prevenir-los-desordenes-fisiologicos-en-tomates-de-invernadero/

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