TOMATO GUIDE OF FERTILIZATION
May 12, 2017

Growing tomato and getting high yield is a task that requires profound knowledge and expertise. Best fertilization regime should be based on leaf or soil analysis. Here are just some of the information for reference :

TOMATO

The tomato is the edible fruit of Solanum lycopersicum, commonly known as a tomato plant, which belongs to the nightshade family, Solanaceae.

Its use as a food originated in Mexico, and spread throughout the world following the Spanish colonization of the Americas. Tomato is consumed in diverse ways, including raw, as an ingredient in many dishes, sauces, salads, and drinks. While tomatoes are botanically berry-type fruits, they are considered culinary vegetables, being ingredients of savory meals.

Tomatoes are considered a fruit or vegetable depending on context. According to Encyclopedia Britannica, tomatoes are a fruit labeled in grocery stores as a vegetable due to (the taste) and nutritional purposes.

Numerous varieties of tomato are widely grown in temperate climates across the world, with greenhouses allowing its production throughout the year and in cooler areas. The plants typically grow to 1–3 meters (3–10 ft) in height and have a weak stem that often sprawls over the ground and vines over other plants. It is a perennial in its native habitat, and grown as an annual in temperate climates. An average common tomato weighs approximately 100 grams (4 oz).

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FERTILIZATION

The tomato is grown worldwide for its edible fruits, with thousands of cultivars.A fertilizer with an NPK ratio of 5-10-10 is often sold as tomato fertilizer or vegetable fertilizer, although manure and compost are also used.

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. 

Phosphorus (P) and secondary nutrients, Ca and Mg, are required at a relatively constant rate, throughout the life cycle of the tomato plant.

Fig. 1 The uptake dynamics of the macro- and the secondary nutrients by a tomato plant

The uptake dynamics of the macro- and the secondary nutrients by a tomato plant.jpg

Fig. 2 Element composition of a tomato fruit:

Fig. 3 Element composition of a tomato plant:


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. 

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.

Enhances resistance toward bacterial viral, nematodes and fungal pathogens. 

Reduces the occurrence of coloration disorders and blossom-end rot.

Increases solids content in the fruit.

Improves taste.

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.

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