Tomato is one of the most spreaded agricultural products all around the world and even of higher economic value. Its demand is continuously increasing and with it, the crop, production and trade. The world production is of 85 millions of tons (FAO 2007) and the countries with higher productions are China, Mexico, United States, Turkey, Spain, Italy and Egypt. Continentally, according to FAO data, Asia participates with no more than 50%, followed by America with a 20%, Europe 15% and the rest comes from Oceania and Africa.
Temperatures higher than 35ºC affect the development of the fruit, due to the incorrect development of the ovule and the crop in general. The ripening of the fruit is very influenced by the temperature, so values near the 10ºC as higher than 30ºC create yellowish tonalities.
The tomato plant is not very exigent with soils. The crop develops so much in good drainage soils (rich in organic material) as in clay sand soils. The tomato is the crop which better tolerates the salinity conditions so much from soil as from irrigation water.
The spacing is established depending the size of the plant, which will depend on the commercial variety. The most frequently used is of 1,5 meters between lines and 0,5 meters between plants, although when size is medium it is common to increase the density of the plantation to two plants by square meter with frames of 1 m x 0,5 m.
Not only the quantity of water determines the production, but also the application moment which imposes the physiology of the crop. It is necessary to know the requirements of water necessary on each phenologic state of the crop to obtain in this way the maximum economic output.
In the protected tomato crops the living of water and great part of the nutrients it is made generally through drip irrigation and according the phenologic state of the crop as the environment in which it is developed (type of soil, climatic conditions, quality of irrigation water, etc.).
In soil cultivation and sand culture; the establishing of the moment and irrigation volume will be given basically by the following parameters:
- Tension of water in soil (matrix tension), which will be read with the adequate use of tensiometers, being convenient to irrigate before reaching the 20-30 centibars.
- Type of soil (capacity, saturation percentage).
- Evapotranspiration of the crop.
- Irrigation efficiency (uniformity of drippers flow rate)
- Quality of irrigation water (when the quality is low, the volumes of water are higher because it is necessary to move the salts from the humidity bulb).