A complete guide to tomato production in the greenhouse ( Part two)

Criteria for the selection of plant material

Tomato is a species that does not respond to photoperiodism (the number of hours of light per day). Thus, can be used in different planting material. However, when selecting varieties or hybrids of tomatoes, consider the following characteristics:

Type of growth

Basically, there are two types of tomato growth: indeterminate and determinate. It is important to determine the type of growth for tomato you want to plant, as this and features of a greenhouse can vary in aspects related to economic issues and managing culture. In turn, indeterminate varieties are two forms of growth and development of plants. On the one hand, it can be plants of open growth, which, as a rule, earlier, with long internodes, small leaves and fruit of medium size. These varieties are well suited for greenhouses that have a high structure for a garter of plants and mainly in those cases when the greenhouse has ventilation problems, because their lower density of leaves facilitates this feature.. on the other hand, they can be varieties of compact growth, which are characterized by short internodes, excessive vegetative growth and large fruit.

The size and shape of the fruit

Size refers to diameter of the fruit in the middle. The size of the fruit, the tomatoes can be classified as large when the diameter is greater than 82 mm, medium, with a diameter from 57 to 81 mm, and smaller, with a diameter less than 56 mm. with regard to form, the fruit of tomato can be substantially spherical, rounded or flattened. These characteristics are largely determined by the market and the type of packaging for marketing; for example, for presentation in trays required is flattened and average the results.

Form of maturation

There are basically three forms of fruit ripening. Standard maturation, when the fruit changes color simultaneously along the whole surface; green top, when at puberty the upper part remains dark green in color; and the top is slightly green.

Post-harvest storage

Duration of post-harvest storage life of the fetus is an aspect of paramount importance in the selection of material for cultivation. The market offers a wide range of materials, which are characterized by a long shelf life by incorporating genes that slow the maturation and provide greater density of the skin.

Genetic resistance to diseases and physiological disorders

A very important factor when choosing the material. The specifications of different varieties (hybrids) or materials specified resistance and/or tolerance to each of them.

Different tomato varieties offered resistance to the following major pathogens:

• TMV = tobacco mosaic virus

• TYLCV = virus yellow leaf curl of tomato

• ToMV = tomato mosaic virus

• TSWV = virus bronzovoi tomato

• C2 = Cladosporium fulvum, race A and B

• C5 = Cladosporium fulvum, race A, B, C, D, and E

• V = Verticillium

• F2 = Fusarium oxysporum f. lycopersici races 1 and 2

• Fr = Fusarium oxysporum f. radicis lycopersici

• N = nematodes

• PST = Ralstonia

• S = Stemphylium

To physiological disorders that should be considered when choosing the material, is fruit cracking, low temperature and uneven ripening of the fruit, known as spotting. There are also varieties or hybrids resistant or tolerant to such environmental conditions as drought, salinity, heat or cold.

Structure, methods of propagation and management methods

Infrastructure

The nursery is a place designed for controlled production of seedlings of good quality to final landing. Selected to create the site should have good drainage and ventilation. The orientation and layout should provide good brightness, easy access and implement management techniques.

For the propagation of plants need greenhouse facilities, containers for rooting and fertigation system. A greenhouse is a structure made of metal or wood, covered with transparent material, usually plastic film. Its functions:

a) improve the condition of the environment to facilitate germination so that the selected substrate and humidity remain constant;

b) protection against adverse atmospheric influences such as wind and rain;

C) preventive phytosanitary protection, isolation of seedlings from the centers of external contaminants. Racks or tables for rooting are used to place cassettes with seedlings to isolate the plants from the soil, contribute to the normal pruning of the roots and facilitate the work.

And finally, the system of irrigation and/or fertigation, as the name suggests, is an equipment used for irrigation and plant nutrition. For efficient irrigation it is necessary to have an adequate supply of water of good quality for agricultural purposes, free from pathogens and without excessive salt. The system used must guarantee easy adjustment of the frequency, quantity and uniformity of irrigation, as well as to ensure that the droplet size and the use of pressure did not affect the normal development of the seedlings. Irrigation systems range from hand tools such as watering cans and hoses, before the automated fogging.

Substrates and containers

The substrate is a breeding ground where developing root system of the seedling. The substrate used for growing tomatoes needs to have certain characteristics that ensure the proper development of seedlings. Some of these characteristics:

• To be a support for the plants; it should be easy (bulk density less than 0.2 g/cm3) and also have a high percentage of porosity.

• To provide a high water-holding capacity.

• To have good drainage and aeration.

• Have a low tendency to compaction.

• To be free from pathogens, weed seeds and nematodes.

There are several substrates suitable for the production of seedlings of vegetables in magazines. Currently available soilless mixes, which usually contain peat, coconut fiber, perlite, vermiculite, nutrients and wetting agents. Soilless mixes are choosing according to these criteria:

a) the offer and homogeneity. The selected material should be uniform and easily accessible;

b) physical, chemical and biological properties should ensure the optimal development of plants;

C) experience, not all substrates require the same management, it is recommended to make a preliminary assessment before using new substrates or mixtures;

g) cost, at the same time, it is important not to jeopardize the quality of seedlings.

The main substrates for production of seedlings are peat and coconut fiber. Peat is mainly of fossilized plants, comprising the remains of mosses and other partially decomposed plants. Depending on the degree of decomposition, klassificeret white and black peat. White is less decomposed and is widely used as a substrate, as it retains part of its structure and has excellent physical and chemical properties. Black peat is deeper and the degree of decomposition it more than the white. Because of its structure, it have poor ventilation and high content of soluble salts.

Physical and chemical properties of peat improve by adding other materials that enhance the porosity, acidity, and level of supply. Usually the peat is prepared for sale, has a pH of from 5.5 to 6.5 and a conductivity in the range from 0.7 to 1.1 dS/m. For sale peat is Packed into bales of from 107 to 300 liters in the compressed state or in bags of 80 liters in a state of fluff. Although this is an expensive substrate, peat has good physical properties such as low bulk density (from 0.05 to 0.15 g/cm3), high percentage of porosity and high water holding capacity.

Because of the homogeneity and availability of coconut fiber stands out as an alternative to peat. This is a byproduct of the processing mezokorticalna fiber fruits with high capacity aeration, optimum pH and adequate levels of nutrients, especially phosphorus and potassium (Berjón et al., 1999). Commercial presentation coir is similar to peat.

In the industrial production seedling need to use containers that allow every seed to plant in a container and to extract the intact root system of seedlings, which facilitates transport and transplant. The containers are usually plastic cassette with numerous cells of small sizes and volumes ranging from 9 to 25 cubic centimeters. For tomato, it is recommended to use a cassette with a cell volume of more than 18 cubic centimeters.

Various studies show that the size of the container is a determining factor in the quality of seedlings. The larger the container, the more leaf area, biomass and volume of roots (Cantliffe, 1993). The growth of vegetative buds correlated with the growth of the root system and may be upset when the root system is restricted to small volumes of rooting; similarly, plants with good root system development, better tolerate transplanting (Nesmith and Duval, 1998).

Stages of production of seedlings

Production of planting materials requires special equipment and relevant infrastructure for the establishment and normal development of the material for reproduction. Each of the stages of the production process must be properly planned and implemented, to meet the technical requirements established for the production of tomato seedlings with the relevant quality standards.

Preparation of substrate

Includes the choice, preparation of the substrate and filling the containers. At this stage you should determine the nutrient levels, pH and the concentration of salts in the substrate, which is expressed through the electrical conductivity (EC), in order to amend. The pH value must be within the range of 5.0 to 6.5. The level of salt varies depending on the amount of fertilizer in the mixture. Acceptable electrical conductivity from 1.0 to 2.0 dS/m. In the preparation the substrate must be very well crumble and provide uniform wetting. To fill the containers, it is recommended to completely fill the cells and to prevent compaction of the substrate.

Sowing and germination

Tomato seeds are flat and lenticular. On average, one gram contains from 250 to 350 seeds, depending on variety. Due to the costs of new production technology of seedlings need high quality seeds to ensure rapid germination, good uniformity and endurance of plants. The use of cassette tapes for reproduction has advantages, such as the most effective use of the seeds because you planted one seed per cell; it is easy to move the seedlings from place to place; saved when using the substrate, and slight damage to the root system.

Seeds should be sown to a depth of 5 to 10 mm and covered with the same substrate, which had been sown to ensure that they will remain moist. Seed germination is an important step in the process of production of seedlings. Tomato seeds require good aeration for germination, so it is necessary to avoid waterlogging of the substrate. The optimum temperature for germination is between 23 to 25 ° C. the Time required for germination depends on the variety and seed weight, but in General, the germination and emergence occurs between 3 to 6 days after sowing.

Development of seedlings

Includes the time from planting and germination to achieve proper development of leaves for transplanting.

Control methods

The quality of the duplicated material is the decisive factor to produce a crop that meets the requirements. This quality, in turn, is a response to managing the development of seedlings. The main methods of control during breeding of tomatoes are:

Nutrition and irrigation

Irrigation and nutrition program have a significant effect on seedling growth. It is advisable to do a full analysis of irrigation water. The amount and frequency of irrigation changed depending on the volume of cells, substrate, greenhouse ventilation and weather conditions. The General recommendation is to water daily magazine sprinkler irrigation or, in his absence, to pour a thin stream to avoid erosion of the seeds. Watering should be 2 or 3 times a day, depending on climatic conditions and plant growth, making sure that each cell was completely moist to promote root growth at the bottom of the cell.

Nutrition of the seedling is carried out using a commonly used nutrient solutions. The concentration of the nutrient solution is determined by the amount of nutrients that it contains. This concentration is expressed in units called parts per million (ppm) or mmol/l Moderate increase in concentration leads to an increase in height, diameter of stem and weight of plants, while very high concentrations may lead to high and weak plants of low quality.

The optimal pH and electrical conductivity (EC) varied depending on the stage of development of seedlings and construed in accordance with the methodology used to define them. Power adjustment must be made on the basis of physical and chemical analysis of the material that was used as a substrate for seeds. The table shows the appropriate levels of nutrients for the substrate used for the production of tomato seedlings (Alarcón and Egea, 1999).

Control and prevention of diseases of crops
The best way of fight against diseases of the seedlings and preventive phytosanitary measures and the proper management of environmental conditions in the greenhouse. Among the most recommended methods of disease prevention:
Control weeds around the greenhouse.
Disinfection of magazines for seeds, if they are reused.
Ventilation of the greenhouse (promotes air circulation around the seedlings).
Prevention of waterlogging and the use of the substrate of good quality.

Standards of quality seedlings

Tomato seedlings suitable for transplantation if it meets the following requirements:
Height ranges from 10 to 15 cm,there are at least four of these formed sheet, and there is a good uniformity between plants in the cassette.
The leaves are well developed, they are green, straight and free of kinks.
At the base of the stem and on the underside of leaves coloring slightly purple.
Cotyledons completely healthy.
The roots are soft and delicate, fill the entire container from top to bottom. Roots with brown
color that do not reach the bottom of the container, are a symptom,
what plants grow under conditions of moisture stress, which can slow down
rooting for a permanent place.

Grafting tomatoes

Grafting is the joining of two parts
living plant tissue so that they unite and develop as
a single plant (Hartmann and others 1997). Tomato is one of vegetables,
which is widely used this practice; in 2000, in Japan, was grafted to
48% of tomatoes grown in greenhouse (Lee, 2003).
Grafting tomato facilitates the management and control of diseases by the use of rootstocks with some resistance to diseases that develop in the soil. These rootstocks allow to keep the plants healthy and vigorous longer. This application also increases yield. On the other hand, an increase was noted in the results and the quality by using rootstocks tolerant to stress conditions, such as
salinity. The main limitation of the use of vaccination in the production of
tomatoes are additional costs for the farmer and necessary workers.

UTADEO,
Inga Kostenko, Mivena, Ukraine
Anna Ustymenko, Club Sirius Agro Plant