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Pioneering the Future

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Crop Guide: Tomato

Index:
 

1. Tomato crop guide: 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.

(Source: Huett, 1985)

 

Figure 5: The uptake dynamics of the macro- and the secondary nutrients by a tomato plant
Uptake rate 
(g/plant)
 
 
 
 
Figure 6: Daily uptake rates of plant nutrients by processing tomatoes yielding 127 T/ha 
(Source: B. Bar-Yosef . Fertilization under drip irrigation)
Uptake rate 
(kg/ha/day)
 
 
Days after planting
 
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)

 

2. Tomato crop guide: Main functions of plant nutrients

Table 5: Summary of main functions of plant nutrients:
Nutrient
Functions
Nitrogen (N)
Synthesis of proteins (growth and yield).
Phosphorus (P)
Cellular division and formation of energetic structures.
Potassium (K)
Transport of sugars, stomata control, cofactor of many enzymes, reduces susceptibility to plant diseases.
Calcium (Ca)
A major building block in cell walls, and reduces susceptibility to diseases.
Sulphur (S)
Synthesis of essential amino acids cystin and methionine.
Magnesium (Mg)
Central part of chlorophyll molecule.
Iron (Fe)
Chlorophyll synthesis.
Manganese (Mn)
Necessary in the photosynthesis process.
Boron (B)
Formation of cell wall. Germination and elongation of pollen tube.
Participates in the metabolism and transport of sugars.
Zinc (Zn)
Auxins synthesis.
Copper (Cu)
Influences in the metabolism of nitrogen and carbohydrates.
Molybdenum (Mo)
Component of nitrate-reductase and nitrogenase enzymes.

 

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 Multi-K® potassium nitrate, the EC increases without adverse effect on the yield that increases as well (Table 6). 
 
Nutrient
Functions
Nitrogen (N)
Synthesis of proteins (growth and yield).
Phosphorus (P)
Cellular division and formation of energetic structures.
Potassium (K)
Transport of sugars, stomata control, cofactor of many enzymes, reduces susceptibility to plant diseases.
Calcium (Ca)
A major building block in cell walls, and reduces susceptibility to diseases.
Sulphur (S)
Synthesis of essential amino acids cystin and methionine.
Magnesium (Mg)
Central part of chlorophyll molecule.
Iron (Fe)
Chlorophyll synthesis.
Manganese (Mn)
Necessary in the photosynthesis process.
Boron (B)
Formation of cell wall. Germination and elongation of pollen tube.
Participates in the metabolism and transport of sugars.
Zinc (Zn)
Auxins synthesis.
Copper (Cu)
Influences in the metabolism of nitrogen and carbohydrates.
Molybdenum (Mo)
Component of nitrate-reductase and nitrogenase enzymes.
Nitrogen (N)
 
Table 6: The effect of nitrogen form (NO3- and NH4+) on tomato yield - showing the advantages of nitrate-nitrogen over ammoniacal nitrogen. (source: U. Kafkafi et al. 1971)
NO3- : NH4+
ratio
N g/plant
EC
(mmho/cm)
Yield
(kg/plant)
Multi-K® 
potassium nitrate
Ammonium Nitrate
100 : -
6.3
-
1.7
2.5
70 : 30
6.3
4.4
2.4
1.98
63 : 37
6.3
8.7
2.9
1.20
59 : 41
6.3
13.2
3.5
1.00
100 : -
12.6
-
3.1
3.43
 
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:

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.

1. Balancing of negative electrical charges in the plant
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.
 
2. Regulating metabolic processes in cells
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:

3. Regulation of osmotic pressure

  • 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 Multi-K® application rates increases lycopene content of the tomato. The function is described by an optimum curve (Fig. 10).

 

Figure 10: The effect of Multi-K® rate on lycopene yield in processing tomatoes
Lycopene
yield
(mg / plant)
 
 
K rate(g/plant)
 
Multi-K® 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). Multi-K® 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 Multi-K® application methods and rates, as a source of K, combined with other N and P fertilizers:
Method of application
N-P2O5-K20
kg/ha
 
Base-dressing and side-dressing
120-140-260
1) 10 days prior to transplanting:  
65% of N & K rates, and the entire P
 2)  26 days after transplanting (initial flowering):  10% of N & K rates
 3) 51 days after transplanting (initial fruit-set ): 
25% of N & K rates as Multi-K®
Base-dressing and Fertigation I
120-140-260
10 days prior to transplanting: 
30% of N, P & K rates, 350 kg/ha of Multi-K® in a blend: 12-20-27.
 During the entire plant development stages, 70% of N-P-K as Multi-K®  + Soluble NPK’s + Multi-P (phos. acid), 12 weekly applications by fertigation
Base-dressing and Fertigation II
160-180-360
(34% higher rate)
10 days prior to transplanting: 
30% of N, P & K rates as 400 kg/ha, a Multi-K® in a blend: 12-20-27.
 During the entire plant development stages, 70% of N-P-K as Multi-K®  + Soluble NPK’s + Multi-P (phos. acid), 12 weekly applications by fertigation
 
Figure 11: The effect of application method and rates of Multi-K® potassium nitrate on the dry matter yield and brix level of processing tomatoes cv Peto.
 Dry matter yield
(ton/ha)
 
 
 
 
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. Tomato crop guide: Nutrients deficiency symptoms

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
 
Haifa's solution: Haifa Micro™
 
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.
 
Haifa's solution: Haifa Micro™
 
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.
 
Haifa's solution: Haifa Micro™
 
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
 
Haifa's solution: Haifa Micro™
 

4. Tomato crop guide: 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
 
A. Macro and secondary nutrients
Nutrient
Conc. in leaves (%)
Before fruiting
During fruiting
N
4.0-5.0
3.5-4.0
P
0.5-0.8
0.4-0.6
K
3.5-4.5
2.8-4.0
Ca
0.9-1.8
1.0-2.0
Mg
0.5-0.8
0.4-1.0
S
0.4-0.8
0.4-0.8
 
 
B. Micronutrients
Nutrient
Conc. in leaves (ppm)
Before fruiting
During fruiting
Fe
50-200
50-200
Zn
25-60
25-60
Mn
50-125
50-125
Cu
8-20
8-20
B
35-60
35-60
Mo
1-5
1-5
 
Toxic levels for B, Mn, and Zn are reported as 150, 500, and 300 ppm, respectively
 
 
5.Tomato crop guide: Overall nutritional requirements
 
Table 9: Overall requirements of macro-nutrients under various growth conditions
Fertilizer
Yield (ton/ha)
N
P2O5
K2O
CaO
MgO
 Outdoor
80
241
 62
 416
 234
 67
150
417
108
 724
 374
 110
 Processing
60
196
 50
 336
 203
 56
100
303
78
 522
 295
 84
 Tunnels
100
294
 76
 508
 279
 80
200
536
139
 934
 463
 138
 Greenhouse
120
328
 85
 570
 289
 86
240
608
158
 1065
 491
 152
 
 
 
Need more information about growing tomatoes? You can always return to the tomato fertilizer & tomato crop guide table of contents