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GREENHOUSE TOMATOES: BOOSTING YIELDS

The tomato, king of the greenhouse crops. It is characterised by its adaptability to different systems, climates and seasons, which gives it a differential value in terms of production, research and development.

Although most tomato production is open-field, it is increasingly grown in greenhouses or plastic tunnels, as this allows the supply of fresh, quality fruit to local and international markets all year round.

Annual production has increased in recent times, which can be explained by the higher yield per square metre of greenhouse tomatoes. Under favourable conditions, greenhouse tomatoes can have two annual harvests, with high-quality fruit production.

Greenhouse tomato varieties

Of all the available greenhouse tomato varieties, we have highlighted the following based on their common characteristics:

  • Beefsteak. Plants with vigorous growth up to the sixth or seventh branch; after this, growth slows coinciding with the swelling of the first clusters. Large, soft fruits. Early, clustered production.
  • Marmande. Slow-growing plants that produce four to six usable clusters. The flattened, ribbed fruit has a characteristic pleasant flavour and multiple cavities, which may vary according to the growing season.
  • Cocktail. Very slender, indeterminate plants. Their round fruits weigh between 30 and 50 grams. They generally have two cavities and are prone to splitting. They are used mainly as a garnish.
  • Cherry. Vigorous, indeterminate plants. They produce small fruits with thin skins that are prone to splitting, which are grouped in clusters of 15 to over 50 fruits. Pleasant, sweet flavour. Some cultivars produce red and yellow fruits. This product was developed to allow for year-round production.
  • Long-life. This is the type mainly grown in the Almería province. Nor and Rin genes have given it a long life, leading to firmer fruits that can be stored for longer before their sale, but with less flavour. Generally, the fruits should be G, M or MM gauges, with a smooth surface and a uniform orange or red colour.
  • Smooth. Varieties cultivated for the domestic market and Italy, sold with mixed colouring and less vigorous than the long-life type.
  • Truss. Increasingly available commercially, it is difficult to define the best type of truss tomato, but the following characteristics are generally preferred: bright red M-calibre fruits, inserted as clusters in a herringbone fashion, etc.

Factors affecting greenhouse tomatoes

Soil

Greenhouse tomatoes perform optimally in well-drained soil, preferably loose, silty-clay soils rich in organic matter. They can tolerate salinity up to 3.5 dS/m in saturated extract. Above these values, productivity drops considerably, although the quality of the tomato is enhanced. The recommended pH of soils can vary from slightly acidic to slightly alkaline when sand mulching is used.

Temperature

The ideal temperature for optimal tomato development is 20–30ºC during the day and 5–18ºC at night. Very extreme temperatures affect the growth, setting and production of plants, although problems with growth and pollination can also occur at temperatures below 15°C. Conversely, temperatures above 35ºC reduce pollination and pollen quality.

Relative humidity

Temperature determines the ideal moisture level for greenhouse tomatoes. The combination of relative humidity and temperature determines:

  • The stress level that the crop will need to withstand, in addition to its ability to transpire and grow.
  • The amount of water vapour in the greenhouse atmosphere.
  • Vapour pressure deficit (VPD).

The ideal relative humidity is between 60 and 80%. Beyond this level, the fruit is prone to splitting or infection from fungi and bacteria. Below 60%, water stress and problems with pollen adhering to flower stigma can occur.

Sunlight

Greenhouse tomatoes may need 8 to 16 hours of light per day. Anything less than this and the crop may experience difficulties with flowering and fruit-setting, excess foliage and smaller and lower quality fruits. However, if it receives more than the recommended amount of light, the fruits may be deformed and growth of the tomato may be stunted.

FERTIGATION AND DFINNOVA RIPENING SOLUTION

In protected tomato crops, water and the bulk of the nutrients are generally provided through drip irrigation and depend on the phenological phase of the plant, along with the environment in which it is growing (soil type, climate conditions, water quality, etc.).

For crops grown in soil and with sand mulching, the length and volume of irrigation will chiefly depend on the following parameters:

  • Water content of the soil.
  • Soil type (field capacity, saturation percentage).
  • Crop evapotranspiration.
  • Irrigation efficiency (uniformity of drip flow).
  • Irrigation water quality (the lower the quality, the more volume of water is required to displace the salt front from the moisture bulb).

In practice, the irrigation frequency for a sand-mulched crop in Almería is 2–3 times a week in winter, increasing to 4–7 times a week in spring/summer, with flows of 2–3 litres per plant.

Nutritionally, attention should be paid to the importance of the N:K ratio during the growing cycle, which is usually 1:1 from transplanting to flowering but shifts to 1:2 and even 1:3 during the harvesting period. When growing cluster tomatoes, potassium has an essential role in ripening, and can be used in the form of potassium nitrate, potassium sulphate, monopotassium phosphate or chelate.

Phosphorus is important during the rooting and flowering stages, since it is crucial for root formation and flower size. It can be overused to shorten internodes during early periods when the plant tends to grow poorly. In winter, we should increase this element, along with magnesium, to prevent severe deficiencies due to soil cooling.

Calcium is another essential macronutrient in tomato nutrition for preventing blossom end rot, which is usually caused by a calcium deficiency or blockage in generally saline soils or by extremely irregular watering.
Iron is one of the most important micronutrients in tomato nutrition, given that it plays a key role in fruit colouring.

With DFINNOVA’s technological solutions, you can produce higher-quality fruits (brix grades, pigmentation/colour, firmness, skin quality, etc.)
By implementing Crux and Draco consecutively, we can boost yields, enhance harvests and achieve better post-harvest quality.

Crux: a root-applied biostimulant solution recommended to help fruits to ripen and grow bigger. The AP® technology complex ensures effective and efficient absorption of water and nutrients for the lowest energy expenditure.

  • Activates the absorption and mobilisation of potassium.
  • Improves soil chemical properties.
  • Unlocks macronutrients and micronutrients.

DRACO: fast-response foliar application biostimulant (direct to the phloem) which naturally strengthens ripening processes (metabolic regulation of methionine) resulting in a significant improvement of fruit quality (brix, pigments, vitamins, etc.) without causing early ripening. It contains EUe® technology, which increases leaf absorption and promotes translocation inside the vascular bundles to the plant organs. (immediate action)

  • Speeds up ripening.
  • Induces activation of enzymes involved in fatty acid production.
  • Supports biosynthesis of vitamin B1.

The management programme for DFINNOVA ripening solutions ensures that elements are added at each stage of the process. It does not induce ripening, but it helps speed it up and bring harvesting forward.

As you know, at DFINNOVA, you have a team of skilled experts who can help you manage your crops with our wide range of technological solutions, including complete nutrition and biostimulation programmes, to optimise yields.

Reach out to us, we are here to support you and are always happy to help.