26 1月 2018

Nutritional recommendations for TOMATO in open-field, tunnels and greenhouse

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1. About the crop

1.1 Growth patterns-Nutritional recommendations for TOMATO in open-field, tunnels and greenhouse

Tomato cultivars may be classified into three groups by their growth patterns, which are recognized by the arrangement and the frequency of leaves and the inflorescence on the stem.

a) Indeterminate growth – the main and side stems continue their growth in a continuous pattern. The number of leaves between inflorescence is more or less constant, starting from a specific flowering set (Fig. 1a). Cultivars of indeterminate growth are usually grown as greenhouse or staked tomatoes.

b) Determinate growth – the main and side stems stop growth after a specific number of inflorescences that varies with the specific cultivar (Fig. 1b). Processing tomatoes are often belong to determinate cultivars.

c) Semi-determinate growth – branches stop growth with an inflorescence, but this usually occurs at an advanced growth stage. Cultivars of this group are usually grown as out-door, non-staked tomatoes.

Table 1: Number of leaves between inflorescence in different growth patterns

1.2 Growth stages

Growth stages of plants, in very general terms, can be split into four periods:

  • Establishment from planting or seeding during vegetative growth until first flower appears.
  • From first flowering to first fruit set
  • From fruit ripening to first harvest
  • From first harvest to the end of last harvest.

These growth periods also represent different nutritional needs of the plant (see section 3.1).

The duration of each stage may vary according to growing method, variety characteristics and climatic conditions (Table 2).

Table 2: A typical example of a growth cycle in central Israel by growth stages

1.3 Fruit development

After fruit setting, fruit ripens over a period of 45 – 70 days, depending upon the cultivar, climate and growth conditions. The fruit continues growing until the stage of green ripeness.

Three fruit developmental stages are noted.

Ripening occurs as the fruit changes color from light green to off-white, pink, red, and finally dark red or orange. Depending on the distance and time to market, harvest may occur anytime between the pink to dark red stage, the later stages producing more flavorful fruit.

Table 3: Stages of fruit ripening

1.4 Crop uses

Tomatoes are consumed fresh, and are being processed to pickles, sauce, juice and concentrated pastes

Growing conditions

2.1 Growing methods

Soil or soilless, protected crop (greenhouse or high plastic tunnel) or open field.

2.2 Soil type

Tomatoes can be grown on soils with a wide range of textures, from light, sandy soils to heavy, clay soils. Sandy soils are preferable if early harvest is desired. Favorable pH level: 6.0-6.5. At higher or lower pH levels micronutrients become less available for plant uptake.

2.3 Climate

Temperature is the primary factor influencing all stages of development of the plant: vegetative growth, flowering, fruit setting and fruit ripening. Growth requires temperatures between 10°C and 30°C.

Table 4: Temperature requirements during different growth stages:

Light intensity is one of the major factors affecting the amounts of sugars produced in leaves during the photosynthesis, and this, in turn, affects the number of fruits that the plant can support, and the total yield.

2.4 Irrigation

Tomato plants are fairly resistant to moderate drought. However, proper management is essential to assure high yield and quality. The water requirement of outdoor grown tomatoes varies between 4000 – 6000 m³/ha. In greenhouses up to 10,000 m3/ha of water are required. 70% or more of the root system are in the upper 20 cm of the soil. Therefore, a drip system equipped with a fertigation device is advisable. On light soils or when saline water is used, it is necessary to increase water quantities by 20% – 30%. Water requirements will differ at various growth stages. The requirement increases from germination until beginning of fruit setting, reaching a peak during fruit development and then decreasing during ripening. Mild water stress during fruit development and ripening has a positive effect on fruit quality: firmness, taste and shelf-life quality, but may result in smaller fruit. Late irrigation, close to harvesting, may impair quality and induce rotting. Water shortage will lead to reduced growth in general and reduced uptake of calcium in particular. Calcium deficiency causes Blossom End Rot (BER) (see page 15). On the other hand, excessive irrigation will create anaerobic soil conditions and consequently cause root death, delayed flowering and fruit disorders.

Water quality: Tomatoes tolerate brackish water up to conductivity of about 2-3 mmho/cm. Acidic (low pH) irrigation water is undesirable, as it might lead to the dissolution of toxic elements in the soil (e.g. Al3+).

2.5 Specific sensitivities of the tomato plant

Sensitivity to soil-borne diseases

Tomatoes are prone to soil-borne diseases caused by fungi, viruses or bacteria. Therefore it is recommended to avoid growing tomatoes on plots that used for other sensitive crops (peppers, eggplants, Irish potatoes, sweet potatoes, cotton, soybeans and others) on recent years. A regime of 3-year rotation between small grains and tomatoes is recommended.

Sensitivity to salinity

Under saline conditions, sodium cations compete with the potassium cations for the roots uptake sites, and chloride competes for the uptake of nitrate-nitrogen and will impede plant development

(Fig.2) and reduce yield.

Figure 2: Inverse relationship between top dry weight and concentration of plant tissue chloride – the higher the chloride in the plant composition, the lower its dry weight.

Salinity will result in a potassium deficiency in the tomato plants, leading to a low fruit number per plant. Corrective measures under such conditions must include the following steps:
 Abundant application of potassium, as this specific cation can successfully compete with the sodium, and considerably reduce its uptake and the resulting negative effects. (Fig. 3)
 Abundant application of nitrate, as this specific anion successfully competes with chloride, and markedly reduces its uptake and adverse effects.
 Also, calcium helps suppressing the uptake of sodium. When sufficient calcium is available, the roots prefer uptake of potassium to sodium, and sodium uptake will be suppressed.

Figure 3: ACK01 potassium nitrate reverses the adverse effects of salinity in greenhouse tomatoes

Salination of the nutrient solution markedly decreased dry weight of the plant, fruit size and plant height. The addition of 4 or 8 mM ACKO1 potassium nitrate to the salinized nutrient solution markedly increased EC values of the nutrient solution but reversed the said adverse effects caused by the NaCl. Several parameters were improved even over the control as a direct result of the treatment with ACK01, i.e., fruit size and plant height (Fig. 4).

Figure 4: The effect of salinity and ACK01 potassium nitrate on vegetative parameters and fruit size in ‘Pusa ruby’ greenhouse tomatoes.

Zinc improves tolerance to salt stress.Zinc nutrition in plants seems to play a major role in the resistance to salt in tomato and other species. Adequate zinc (Zn) nutritional status improves salt stress tolerance, possibly, by affecting the structural integrity and controlling the permeability of root cell membranes. Adequate Zn nutrition reduces excessive uptake of Na by roots in saline conditions.

Sensitivity to calcium deficiency. Tomatoes are highly sensitive to calcium deficiency, which is manifested in the Blossom-End Rot (BER) symptom on the fruits. Salinity conditions severely enhance BER intensity. Recently, it was found that manganese (Mn) serves as antioxidant in tomato fruit, hence its application to tomatoes grown under salinity can alleviate BER symptoms in the fruits. Special care must be taken to avoid growing conditions, which enhance BER phenomenon.

Plant nutrition

3.1 Dynamics of nutritional requirements

Nitrogen and potassium uptake is initially slow but rapidly increases during the flowering stages.
Potassium is peaking during fruit development, and nitrogen uptake occurs mainly after the formation of the first fruit. (Figs. 5 and 6).
Phosphorus (P) and secondary nutrients, Ca and Mg, are required at a relatively constant rate, throughout the life cycle of the tomato plant.
Figure 5: The uptake dynamics of the macro- and the secondary nutrients by a tomato plant(Source: Huett, 1985)

Figure 6: Daily uptake rates of plant nutrients by processing tomatoes yielding 127 T/ha (Source: B. Bar-Yosef . (Fertilization under drip irrigation

As can be seen in figures 5 and 6, the greatest absorption of nutrients occurs in the first 8 to 14 weeks of growth, and another peak takes place after the first fruit removal. Therefore, the plant requires high nitrogen application early in the growing season with supplemental applications after the fruit initiation stage. Improved N use efficiency and greater yields are achieved when N is applied under polyethylene mulches via a drip irrigation system. At least 50 % of the total N should be applied as nitrate-nitrogen (NO3 ).The most prevalent nutrient found in the developed tomato plant and fruit is potassium, followed by nitrogen (N) and calcium (Ca). (Figures 7 and 8)

Figure 7: Element composition of a tomato plant. (Atherton and Rudich, 1986)

Figure 8: Element composition of a tomato fruit (Atherton and Rudich, 1986)

3.2 Main functions of plant nutrients

Table 5: Summary of main functions of plant nutrients:

Nitrogen (N)

The form in which N is supplied is of major importance in producing a successful tomato crop. The optimal ratio between ammonium and nitrate depends on growth stage and on the pH of the growing medium. Plants grown in NH4+ -supplemented medium have a lower fresh weight and more stress signs than plants grown on NO3 only. By increasing the ammonium nitrate rates, the EC increases and consequently the yield decreases. However, when doubling the rate of ACK01 potassium nitrate, the EC increases without adverse effect on the yield that increases as well (Table 6).

Table 6: The effect of nitrogen form (NO3 and NH4+) on tomato yield – showing the advantages of nitrate-nitrogen over ammoniacal nitrogen.

Potassium (K)

Ample amounts of potassium must be supplied to the crop in order to ensure optimal K levels in all major organs, mainly due to the key role K plays in tomatoes:

1. Balancing of negative electrical charges in the plant

As a cation, K+ is THE dominant cation, balancing negative charges of organic and mineral anions. Therefore, high K concentration is required for this purpose in the cells.

2. Regulating metabolic processes in cells

Main function is in activating enzymes – synthesis of protein, sugar, starch etc. (more than 60 enzymes rely on K). Also, stabilizing the pH in the cell at 7 – 8, passage through membranes, balancing protons during the photosynthesis process.

3. Regulation of osmotic pressure

Regulating plant’s turgor, notably on guard cells of the stomata. In the phloem, K contributes to osmotic pressure and by that transporting metabolic substances from the “source” to “sink” (from leaves to fruit and to nurture the roots). This K contribution increases the dry matter and the sugar content in the fruit as well as increasing the turgor of the fruits and consequently prolonging fruits’ shelf life. Additionally, potassium has the following important physiological functions:

Improves wilting resistance. (Bewley and White ,1926, Adams et al ,1978)
Enhances resistance toward bacterial viral, nematodes and fungal pathogens. (Potassium and Plant Health, Perrenoud, 1990).

Reduces the occurrence of coloration disorders and blossom-end rot. (Winsor and Long, 1968)

Increases solids content in the fruit. (Shafik and Winsor,1964)

Improves taste. (Davis and Winsor, 1967)

Figure 9: The effect of K rate on the yield and quality of processing tomatoes

Lycopene is an important constituent in tomatoes, as it enhances the resistance against cancer.

Increasing ACK01 potassium nitrate application rates increases lycopene content of the tomato. The function is described by an optimum curve (Fig. 10).

Figure 10: The effect of ACK01 rate on lycopene yield in processing tomatoes

ACK-01 was applied, as a source of potassium, either by itself or blended with other N and P fertilizers, to processing tomatoes. The different application methods, side-dressing dry fertilizers or combined with fertigation, were compared in a field trial (Table 7). ACK-01 increased the yield (dry matter) and the brix level as can be seen in Figure 11.

Table 7: Layout of a field trial comparing different ACK-01 potassium nitrate application methods and rates, as a source of K, combined with other N and P fertilizers:

Figure 11: The effect of application method and rates of ACK-01 potassium nitrate on the dry matter yield and brix level of processing tomatoes cv Peto.

Calcium (Ca)

Calcium is an essential ingredient of cell walls and plant structure. It is the key element responsible for the firmness of tomato fruits. It delays senescence in leaves, thereby prolonging leaf’s productive life, and total amount of assimilates produced by the plans.Temporary calcium deficiency is likely to occur in fruits and especially at periods of high growth rate, leading to the necrosis of the apical end of the fruits and a development of BER syndrome.

3.3 Nutrients deficiency symptoms

Tomatoes are rather sensitive to excess or deficiency of both macro- and micro- nutrients. Examples of common deficiencies, particularly in soilless culture, other than those of N and P, are: K deficiency, affecting fruit quality; Ca deficiency, causing blossom-end rot; Mg deficiency, in acid soils and in the presence of high levels of K; and deficiencies of B, Fe and Mn in calcareous soils.

Nitrogen

The chlorosis symptoms shown by the leaves on Figure 12 are the direct result of nitrogen deficiency. A light red cast can also be seen on the veins and petioles. Under nitrogen deficiency, the older mature leaves gradually change from their normal characteristic green appearance to a much paler green. As the deficiency progresses these older leaves become uniformly yellow chlorotic). Leaves become yellowish-white under extreme deficiency. The young leaves at the top of the plant maintain a green but paler color and tend to become smaller in size. Branching is reduced in nitrogen deficient plants resulting in short, spindly plants. The yellowing in nitrogen deficiency is uniform over the entire leaf including the veins. As the deficiency progresses, the older leaves also show more of a tendency to wilt under mild water stress and senesce much earlier than usual. Recovery of deficient plants to applied nitrogen is immediate (days) and spectacular.

Figure 12: Characteristic nitrogen (N) deficiency symptom

 

Phosphorus

The necrotic spots on the leaves on Fig. 13 are a typical symptom of phosphorus (P) deficiency. As a rule, P deficiency symptoms are not very distinct and thus difficult to identify. A major visual symptom is that the plants are dwarfed or stunted. Phosphorus deficient plants develop very slowly in relation to other plants growing under similar environmental conditions but with ample phosphorus supply. Phosphorus deficient plants are often mistaken for unstressed but much younger plants. Developing a distinct purpling of the stem, petiole and the lower sides of the leaves. Under severe deficiency conditions there is also a tendency for leaves to develop a blue-gray luster. In older leaves under very severe deficiency conditions a brown netted veining of the leaves may develop.

Figure 13: Characteristic phosphorus (P) deficiency symptom

Potassium

The leaves on the right-hand photo show marginal necrosis (tip burn). The leaves on the left-hand photo show more advanced deficiency status, with necrosis in the interveinal spaces between the main veins along with interveinal chlorosis. This group of symptoms is very characteristic of K deficiency symptoms.

Figure 14: Characteristic potassium (K) deficiency symptoms.

The onset of potassium deficiency is generally characterized by a marginal chlorosis, progressing into a dry leathery tan scorch on recently matured leaves. This is followed by increasing interveinal scorching and/or necrosis progressing from the leaf edge to the midrib as the stress increases. As the deficiency progresses, most of the interveinal area becomes necrotic, the veins remain green and the leaves tend to curl and crinkle. In contrast to nitrogen deficiency, chlorosis is irreversible in potassium deficiency. Because potassium is very mobile within the plant, symptoms only develop on young leaves in the case of extreme deficiency. Typical potassium (K) deficiency of fruit is characterized by color development disorders, including greenback, blotch ripening and boxy fruit (Fig. 15).

Figure 15: Characteristic potassium (K) deficiency symptoms on the fruit

Calcium

These calcium-deficient leaves (Fig. 16) show necrosis around the base of the leaves. The very low mobility of calcium is a major factor determining the expression of calcium deficiency symptoms in plants. Classic symptoms of calcium deficiency include blossom-end rot (BER) burning of the end part of tomato fruits (Fig. 17). The blossom-end area darkens and flattens out, then appearing leathery and dark brown, and finally it collapses and secondary pathogens take over the fruit.

Figure 16: Characteristic calcium (Ca) deficiency symptoms on leaves

Figure 17: Characteristic calcium (Ca) deficiency symptoms on the fruit

All these symptoms show soft dead necrotic tissue at rapidly growing areas, which is generally related to poor translocation of calcium to the tissue rather than a low external supply of calcium. Plants under chronic calcium deficiency have a much greater tendency to wilt than non-stressed plants.

Magnesium

Magnesium-deficient tomato leaves (Fig. 18) show advanced interveinal chlorosis, with necrosis developing in the highly chlorotic tissue. In its advanced form, magnesium deficiency may superficially resemble potassium deficiency. In the case of magnesium deficiency the symptoms generally start with mottled chlorotic areas developing in the interveinal tissue. The interveinal laminae tissue tends to expand proportionately more than the other leaf tissues, producing a raised puckered surface, with the top of the puckers progressively going from chlorotic to necrotic tissue.

Figure 18: Characteristic magnesium (Mg) deficiency

Sulfur

This leaf (Fig. 19) shows a general overall chlorosis while still retaining some green color. The veins and petioles exhibit a very distinct reddish color. The visual symptoms of sulfur deficiency are very similar to the chlorosis found in nitrogen deficiency. However, in sulfur deficiency the yellowing is much more uniform over the entire plant including young leaves. The reddish color often found on the underside of the leaves and the petioles has a more pinkish tone and is much less vivid than that found in nitrogen deficiency. With advanced sulfur deficiency brown lesions and/or necrotic spots often develop along the petiole, and the leaves tend to become more erect and often twisted and brittle.

Figure 19: Characteristic sulfur (S) deficiency

Manganese

These leaves (Fig. 20) show a light interveinal chlorosis developed under a limited supply of Mn.

The early stages of the chlorosis induced by manganese deficiency are somewhat similar to iron deficiency. They begin with a light chlorosis of the young leaves and netted veins of the mature leaves especially when they are viewed through transmitted light. As the stress increases, the leaves take on a gray metallic sheen and develop dark freckled and necrotic areas along the veins. A purplish luster may also develop on the upper surface of the leaves.

Figure 20: Characteristic manganese (Mn) deficiency

Molybdenum

These leaves (Fig. 21) show some mottled spotting along with some interveinal chlorosis. An early symptom for molybdenum deficiency is a general overall chlorosis, similar to the symptom for nitrogen deficiency but generally without the reddish coloration on the undersides of the leaves. This results from the requirement for molybdenum in the reduction of nitrate, which needs to be reduced prior to its assimilation by the plant. Thus, the initial symptoms of molybdenum deficiency are in fact those of nitrogen deficiency. However, molybdenum has also other metabolic functions within the plant, and hence there are deficiency symptoms even when reduced nitrogen is available. At high concentrations, molybdenum has a very distinctive toxicity symptom in that the leaves turn a very brilliant orange.

Figure 21: Characteristic molybdenum (Mo) deficiency

Zinc

This leaf (Fig. 22) shows an advanced case of interveinal necrosis. In the early stages of zinc deficiency the younger leaves become yellow and pitting develops in the interveinal upper surfaces of the mature leaves. As the deficiency progresses these symptoms develop into an intense interveinal necrosis but the main veins remain green, as in the symptoms of recovering iron deficiency.

Figure 22: Characteristic zinc (Zn) deficiency symptoms.

Boron

This boron-deficient leaf (Fig. 23) shows a light general chlorosis. Boron is an essential plant nutrient, however, when exceeding the required level, it may be toxic. Boron is poorly transported in the phloem. Boron deficiency symptoms generally appear in younger plants at the propagation stage. Slight interveinal chlorosis in older leaves followed by yellow to orange tinting in middle and older leaves. Leaves and stems are brittle and corky, split and swollen miss-shaped fruit (Fig. 24).

Figure 23: Characteristic boron (B) deficiency symptoms on leaves

Figure 24: Characteristic boron (B) deficiency symptoms on fruits

Copper

These copper-deficient leaves (Fig. 25) are curled, and their petioles bend downward. Copper deficiency may be expressed as a light overall chlorosis along with the permanent loss of turgor in the young leaves. Recently matured leaves show netted, green veining with areas bleached to a whitish gray. Some leaves develop sunken necrotic spots and have a tendency to bend downward.

Figure 25: Characteristic copper (Cu) deficiency symptoms.

Iron

These iron-deficient leaves (Fig. 26) show intense chlorosis at the base of the leaves with some green netting. The most common symptom for iron deficiency starts out as an interveinal chlorosis of the youngest leaves, evolves into an overall chlorosis, and ends as a totally bleached leaf. The bleached areas often develop necrotic spots. Up until the time the leaves become almost completely white they will recover upon application of iron. In the recovery phase the veins are the first to recover as indicated by their bright green color. This distinct venial re-greening observed during iron recovery is probably the most recognizable symptom in all of classical plant nutrition. Because iron has a low mobility, iron deficiency symptoms appear first on the youngest leaves. Iron deficiency is strongly associated with calcareous soils and anaerobic conditions, and it is often induced by an excess of heavy metals.

Figure 26: Characteristic iron (Fe) deficiency symptoms

3.4 Leaf analysis standards

In order to verify the correct mineral nutrition during crop development, leaf samples should be taken at regular intervals, beginning when the 3rd cluster flowers begin to set. Sample the whole leaf with petiole, choosing the newest fully expanded leaf below the last open flower cluster.

Sufficiency leaf analysis ranges for newest fully-expanded, dried whole leaves are:

Table 8: Nutrients contents in tomato plant leaves

Macro and secondary nutrients

Micronutrients

Toxic levels for B, Mn, and Zn are reported as 150, 500, and 300 ppm, respectively.

3.5 Overall nutritional requirements

Table 9: Overall requirements of macro-nutrients under various growth conditions

(Followed by fertilizer recommendations.)

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