Tomato



Taxonomy of the Tomato (Solanum lycopersicum L.) according to Cronquist System
Dominium/Superkingdom or Domain: Eucariotae
Regnum/Kingdom: Plantae (Plants)
Subregnum/Subkingdom: Tracheobionta (Vascular plants)
Superdivisio/Superdivision: Spermatophyta (Seed plants)
Divisio/Division: Magnoliophyta Cronquist, 1996 (Flowering plants)
Subdivisio/Subdivision: Magnoliophytina Frohne & U. Jensen ex Reveal, 1996
Classis/Class: Rosopsida Batsch, 1788 (Dicotyledons)
Subclassis/Subclass: Lamiidae Takht., 1993
Superorder/Superordo: Solananae R. Dahlgren., 1992
Ordo/Order: Solanales Dumort., 1829
Subordo/Suborder: Solanineae Engl. 1898
Familia/Family: Solanaceae Juss., 1789
Subfamilia/Subfamily: Solanoideae Kostel, 1834
Tribus/Tribe: Solaninae Dunal in D.C., 1852
Subtribus/Subtribe: Solaninae Dunal in D.C., 1852
Genus: Solanum L. (1753)
Species: Solanum lycopersicum L. (1753)

Taxonomy of the Tomato (Solanum lycopersicum L.) according to APG II System
Regnum/Kingdom: Plantae (Plants)
Clade: Angiospermae
Clade: Eudicodiledonae (Eudicodiledons or Eudicots)
Clade: Angiospermae tricolpates
Clade: Core tricolpates
Clade: Asterids
Clade: Euasterids I
Ordo/Order: Solanales
Familia/Family: Solanaceae Juss., 1789
Genus: Solanum L. (1753)
Species: Solanum melongena L. (1753)


Taxonomy of the Tomato (Solanum lycopersicum L.) according to APWebsite System:



Nomenlature
The tomato was scientifically classified for the first time by Carlo Linneo during 1753 in the genus Solanum, species Solanum lycopersicum (lycopersicum comes from Latino and means “wolves's fishing”).
However, in 1768, Philip Miller changed the name, arguing that the differences from the other Solanum plant species, such as potato and egg-plants, were substantial, such as to justify the creation of a new genus: from here the new scientific name of Lycopersicon esculentum Mill. This name had remarkable success even if it was opposed to the rules of the nomenclature botanic for which if the species is moved in a new genus, the specific epithet (lycopersicum) must not be changed, but alone the name of the genus: H. Karst corrected the mistake in 1881 and published the name Lycopersicon esculentum such formally correct.
The controversy on the scientific name for tomato is not yet over. First, the scientific name attributed to the tomato by Miller was until recently the most widely used, despite the nomenclature error mentioned before. Then, the modern techniques of molecular biology have allowed for accurate phylogenetic trees, which are referred to as the tomato actually really part of the genus Solanum, giving substantially reason to the taxonomy of Linnaeus. The official name is now Solanum lycopersicum L., although the name of Miller still remains in use in many publications.
Regarding the origin of its common name in Italian, it was attributed to the botanist Pier Andrea Mattioli (1501-1577) who in his treatise "Medici Senensis Commentaries" introduced the name mala aurea, then translated literally “apples gold“, although in contrast to the prevalence of varieties of red fruit and golden. Tomato was attributed aphrodisiac properties and for this reason was used in magic potions from alchemists during the sixteenth and seventeenth centuries.
It is said that after its introduction in Europe Sir Walter Raleigh was given charge of this plan to fruition at the Queen Elizabeth, christened with the name of “apples of love” (love apple).
So in other European languages are found expressions: “love apple”, “Liebesapfel”, “pomme d’amour” (or “pomme d’or”), respectively, in England, Germany and France. Also in Sicily, was explicit the reference to love: “pumu d’amuri”.
The Aztecs called it with the name “xitomatl”, the term “tomatl” indicated numerous fruits like each other, usually for juicy. The tomato sauce became an integral part of Aztec cuisine. Today, with the exception of Italian, the old terms were replaced by derivations of the original "tomatl" of the Aztec Indians, who generally showed plants with fruit globose, juicy pulp and numerous seeds.

Origin
The tomato is native to the Andes, especially the strip of land that stretches from northern Chile to southern Ecuador. It was discovered in the first half of the sixteenth century when the Conquistadores Spaniards landed in America. The Aztecs of Mexico and the Incas of Peru were then the oldest of the tomato growers.
The date of his arrival in Europe is the year 1540, when the Spaniard Hernán Cortés returned home and took the samples. Despite in the New World, the tomato was part of the daily diet of the natives, the vegetable symbol of Mediterranean cuisine, was imported to Europe exclusively for ornamental uses and its cultivation and distribution expected until the second half of the seventeenth century. In fact, the tomato arrived in Italy in 1596, but only later, finding favorable climatic conditions in the Italy South, it has a change of its color from the original and distinctive golden color, which gave its name to the plant, the current red, with field selections and then with the grafts.
In early 1600, after nearly a century after its discovery, the tomato was not yet recognized as an edible plant, because it was considered poisonous as other solanaceous plants such as mandrake and nightshade.
The only exception is Italy where in the middle of the sixteenth century, a century before the European mainland, there are already those who consumed raw tomatoes, or fried in oil and salt, or in soups. Only at the end of the eighteenth century the cultivation of tomatoes for food experienced a strong boost. While in France, the tomato was eaten in the court of kings, in southern Italy became the staple food of the poor and workers. Dates from the early eighteenth century, the first transformation technique in tomato sauce to 1762 and the discovery of preservation in glass jars of the vegetable was boiled previously.
The extensive cultivation for food use is reported in more temperate regions of Europe as southern France, Spain, Southern Italy and Sicily, where the product left for commercialization in the Northern markets. From the mid-twentieth century, with the perfecting of the processing techniques and the start of open field cultivation, production and export Italian is one of the world. The cultivation of the product destined for fresh consumption, from meals, canned tomatoes, juice concentrates and is widespread in Campania, Emilia-Romagna, Lazio, Apulia and Sicily.
With reference to the consumption of tomatoes and the destination, although it is always the same species Solanum lycopersicum, we must distinguish between a tomato crop for fresh market and a tomato for processing transformation for the production of peeled, concentrates and juices tomatoes.


The cultivation of tomato in Italy has a total of about 134,500 hectares. Of these, about 127,500 hectares are cultivated in open fields, (cultivation for the table and industry), and approximately 7,000 hectares as a protected crop.
In cultivation in open field, it is estimated that production for fresh consumption are around 20-25%. Instead, The production for processing, destined for the canning industry, is approximately to 75-80%.
In Italy considerable impetus to the cultivation of tomatoes from the mid-nineteenth century for the tireless work of Francesco Cirio, an Italian industry pioneer.

Botanical characters
Plants are initially decumbent, typically growing six feet or more above the ground if supported, although erect bush varieties have been bred, generally three feet tall or shorter. Indeterminate types are "tender" perennials, dying annually in temperate climates (they are originally native to tropical highlands), although they can live up to three years in a greenhouse in some cases. Determinate types are annual in all climates. Tomato plants are dicots, and grow as a series of branching stems, with a terminal bud at the tip that does the actual growing. When that tip eventually stops growing, whether because of pruning or flowering, lateral buds take over and grow into other, fully functional, vines.
Root system is fibrous, sorted, can reach 1.5 m in depth, but most explore the soil to a depth of 0.6-0.7 m.
Stem is pubescent, erect and prostrate, woody, branched. In modern cultivars for processing tomato the stem is determined develop (the growth is interrupted by the differentiation of apical inflorescence) and bushy shape.
Leaves are alternate, pinnate, composed of 7-11 leaflets simple, with glandular hairs (like all the green parts of the plant) that secrete a substance from the characteristic pungent odor. Specifically, most tomato plants have compound leaves, and are called regular leaf (RL) plants, but some cultivars have simple leaves known as potato leaf (PL) style because of their resemblance to that close cousin. Of RL plants, there are variations, such as rugose leaves, which are deeply grooved, and variegated, angora leaves, which have additional colors where a genetic mutation causes chlorophyll to be excluded from some portions of the leaves.
Flowers are in inflorescences (racemes); generally have 5 yellow petals, 5 sepals and 5 stamens with anthers biloculari concresciute forming a cylinder that surrounds the stylus, the ovary is overcome and pluriloculare. The bloom is scalar, with autogamous fertilization is 0.5 to 4% of allogamy.
Fruit is a berry-shaped (elongated, oval, round) and sizes (50-80 g) variables. As a true fruit, it develops from the ovary of the plant after fertilization, its flesh comprising the pericarp walls. The fruit contains hollow spaces full of seeds and moisture, called locular cavities. These vary, among cultivated species, according to type. Some smaller varieties have two cavities, globe-shaped varieties typically have three to five, beefsteak tomatoes have a great number of smaller cavities, while paste tomatoes have very few, very small cavities.On average between fruit setting and maturation spend about 40 days.
The berry is composed of approximately 93-96% of water (the dry matter amounts to 4-7%). The composition of dry matter is schematically as follows:
In the following table it is reported the compositions for different processing tomatoes (table 1).


Table 1 – Composition of tomato fruits (for g 100 of fresh matter).


The berries at the time of detachment from the plant can keep it or not attached to the stem, creating especially mechanical problems (loosening) during processing. The tomato has a long petiole forming a node or joint in the advanced stages of maturation of a cork layer cells that allow them to break: the berries of the cultivars with this joint (cultivars jointed) the collection come off while attached to the cup and the stem. The genetic improvement has selected mutants that do not have this seam (cultivars jointless), or that the present but without the formation of the layer suberificato (cultivars arthritic) for which the berry is detached in the area of insertion of the fruit and, therefore, without stalk.
Seed is flattened, disc-shaped, rough with curved embryo, 1000 seeds weigh 2.5 to 3.5 g (1 g contains about 280-300 seeds).
Plant development: all varieties of tomato in relation to the development of plant development are determinate or indeterminate. In the case of the developing indeterminate, central stem and lateral branches have continued growth. The number of leaves between the inflorescences is more or less permanently from a specific flowering. Indeterminate varieties are grown for fresh market and harvested by hand after a certain period. The tomato development in indeterminate crosses the same phenological stages of development to the one determined, with the difference that in the cultivation in a greenhouse the period of growth and then of harvesting can be much longer than that in the open field.
In the case of plants development determined the central stem and the lateral growth interrupt after a number of inflorescences in dependence of the cultivars. The development of the terminal stem and lateral branches are asked with the production of an inflorescence.
Certain varieties, used for the product by industry, are harvested by hand in 2 or 3 steps, with the machine in a single step. The uniformity of development and fruit (size, maturity) is so important, especially in case of mechanical harvesting.
The tomato goes through various stages of development during its growth:
Certain varieties, used for the product for processing, are harvested by hand in 2 or 3 steps, with the machine in one pass. The uniformity of development and fruit (size, maturity) is so important, especially in case of mechanical harvesting.
The tomato goes through various stages of development during its growth:
Each stage involves different nutritional needs.
A description is now the growth stages of tomato in the open field. The information is purely indicative, depending on the variety, environmental conditions and crop management.
Pedo-climatic requirements
Climate . The tomato, a native of the tropics, is able to adapt to temperate-hot climates. The needs thermal are shown in table 1. To meet these temperature requirements of the crop, the cultivation cycle in our environments are typical spring-summer, but temperatures over 30-35 ° C cause the folowing of the flowers and fruit drop and various defects in colouring of the berries (lack of lycopene synthesis).

Tabella 1 - Temperatures requirement of the cultivation cycle of the tomato.
Phase and type of temperature °C
Germination
minimun
optimal
Growth
based
minimum lethal
Flowering
minimum
Fruit setting
optimal day time
optimal night time

9-10
20-25

10
0-2

21

22-26
13-16


Regarding to the needs photoperiodic, the tomato is day-indifferent species even if the amount of photosynthetically active radiation intercepted it affects the length of the cycle, with the same cultivars.
The water availability is the other key factor of production which, in hot and dry weather conditions during the spring and summer, irrigation is essential to the operation.
Soil. Tomato on adapts to various soil types but the best productions are obtained in those medium-dough, deep, fresh, fertile, rich in organic matter, with no stagnant water, with pH 6.0 to 7.5. Requires plenty of water for irrigation which requires emergency interventions during the hottest periods.

Cultivation alternation
It 's a typical crop rotation that opens the renewal.
It 's not advisable to repeat the same crop on the same soil in a short time interval. It 'should be replaced with other crops and vegetable species of the nightshade family (peppers, eggplant, potatoes, tobacco), because the plants should be prone to pests such as fungal Verticillium and Fusarium, nematodes, insect infestations and an increase of weeds such as Solanum nigrum.
The autumn-winter cereals are an excellent precession. It 'is therefore to be preferred the alternation with one or two years of wheat or with another renewal.

Tomato for the table and fresh market

General
Worldwide, the total production of tomatoes for the market for direct consumption and processing industry is approaching 100 million tons annually, of which about 27 million were used in the processing industry. The tomato is the first horticultural species cultivated in the world, representing about one-sixth of the total. The Asian continent is the largest: it is grown a little 'less than 50% of the world's a tomato. China and India are the most important countries, with about 22 million tonnes of production, mainly destined to the internal market in recent years, however, China, transformed with the tomato, is also facing the European markets.
The other major producer in the world is represented by the United States, producing about 12 million tonnes of which about 9 processed.
The African continent have produced about 11 million tons of tomatoes, of which over 50% in Egypt.
Also important is the Moroccan production - over 1 million tons -, followed by Algeria and Tunisia. In recent years the production of tomato in the countries of North Africa will benefit greatly the attractiveness of European markets through preferential trade agreements with the EU.
Morocco in particular has oriented its production of fresh market tomato varieties towards the use of long-life (LSL, acronymus of long shelf life), grown in a greenhouse with an advanced cultivation techniques, at competitive costs, whose berries are harvested in winter, mainly from November to March.
In Spain the European supremacy In the European Union produce 16 million tons of tomatoes per year and of these about 9.5 million are absorbed by the processing industry.
Italy, Spain, Greece and Portugal are the largest European manufacturers. Excluding Spain, which is the leading European supplier of tomatoes for the fresh market (over 1,500,000 tons in 17,000 ha of greenhouses located in the South), the other three spend a high percentage of its production to the processing industry.
Spain, Italy and Greece together produce more than 65% of the European tomato for fresh market. The Spanish crop is constantly evolving, although in recent years suffering - like Holland - the competition from the North African productions, particularly those from Morocco. In Greece the production for the fresh market is about 600 000 tons, mainly for the domestic market. France, with about 500 000 tonnes, is the fourth largest European producer of table tomatoes and also has good prospects for export-related, approximately 15% of production. In Northern Europe, particularly in Belgium grown mainly in greenhouses heated, about 2,000 acres of table tomatoes, using almost all the technique of producing 800,000 tons of soil and out marketable.
Among the new countries joined the EU Poland shows high productive potential and competitiveness. Indeed, it has a very favorable geographical position - very close to Germany, most European importing country - also has a very strong commercial potential to Russia, Belarus and Ukraina in the coming years and can play a strategic role in European trade.

The production of the Italian centers
According to the most recent in Italy on table tomato is grown on about 22,000 hectares, capable of providing 900,000 tons of product.
The table tomato cultivars that can be grown in the greenhouse are numerous, with differences based primarily on the shape and size of the fruit. Mostly these are F1 hybrids, characterized by high productivity, disease resistance and uniformity of expression of characters, it looks quite difficult to find in local varieties. The genetic improvement has achieved unimaginable a few years ago, especially in the area of disease resistance, in respect of which were also used genetic engineering methods. Please take note that currently the cultivation of genetically modified organisms (GMOs) is not allowed in any country of the European Union.
In northern regions most concerned in the cultivation of tomatoes for the table are Piedmont, Veneto, Liguria and Emilia Romagna. The crops are produced mainly by farmers farmers specialized in growing vegetables, marketing produce directly to market or give the products in an organized manner.
In the Piedmont region are about 400 hectares for cultivation and cover areas of the following cities: Moncalieri Castiglione and Carmagnola, in the province of Turin, and Isola d'Asti, Motta Castiglione and Govone in the province of Asti.
In Veneto are counted just over 160 hectares mainly in greenhouses. The main production centers are located in the province of Verona in the Cavallino area in Venice, and to a lesser extent in the provinces of Padua and Rovigo.
In Liguria, the cultivation, as well as aim at early and medium early productions, tends to qualify through the preference of varieties of merit as the “Cuore di bue” (heart of the ox). The approximately 100 hectares cultivated in greenhouses are concentrated mainly on the west coast, more precisely in the Albenga plain, while in the east of the affected area is that of Sarzana.
In central Italy another area of considerable importance, where the tomatoes has spread thanks to the climate characteristics of the territory, is the central district of the province of Latina, which fall within the municipalities of Sabaudia and Terracina, up to Sperlonga, Gaeta , Mintrno and Formia. In addition to this, where is the majority of protected horticultural crops in Lazio, distinguish other areas of lesser importance, but were characterized by particular types of production: for example the coast of the coastal province of Rome, but also Tarquinia, where elongated varieties are cultivated from industry gathered at the stage of berry invaiata, much worn in the capital to fuel the various local markets, as well as the towns of Ariccia and Velletri and near Lake of Bracciano. In the cultivation of the province of Viterbo tomato sees its development related to geothermal sources in the area, allowing the forcing of greenhouse cultivars berry round or “semi-costoluta”. Overall in Lazio are more than 850 hectares cultivated in greenhouses and 800 ones in the open field.
The table tomatoes in Sicily has found the maximum spread for optimum soil and climatic conditions: in fact, over 70% of the national table tomatoes is concentrated in the island and that, overall emissions have grown over 4,500 hectares. In this region are more than 10,000 companies involved, mainly located in the southern coast, which sees in the areas of Pachino and Victoria being the most popular.
In Emilia Romagna, the production of table tomatoes "fresh" affects about 80 ectares under shelter, located in the provinces of Forlì-Cesena, Rimini, Bologna and Ferrara. The product obtained mainly supplies the local markets of the provincial capitals.
In the provinces of Emilia, Parma and Piacenza in particular, are cultivated varieties grown in open fields, which are traded on the markets of Milan and Turin as a product invaiato, but mostly as a red tomato transformed directly from consumers.
The successful cultivation of tomato in Sicily, a region important for the cultivation of table tomatoes, comes from far away, in the late 50 years through - it seems - a Sicilian farmer who served his military service in Liguria and the return the island will grow in greenhouses imported wood, similar to those seen precisely in Liguria. The development of cultivation found the maximum pulse later, with the advent of plastic film of polyethylene which allowed the rapid spread, particularly along the coastal strip south of the island. After that time, the evolutionary process of cultivation is in the eyes of everyone, so that the tomato is the leading species in the Sicilian silk. Innovation goes first by modernization of greenhouses, through an increase in space requirements that guarantee the best greenhouse, then the protection of openings with side nets against the afids.
The advent of networks has had a dual function: an initial positive effect was the protection of crops from aphids, whiteflies and Bemisia, insect carriers of dangerous viruses including TYLCV (Tomato Spotted Leaf Curly Virus), the same networks have facilitated the spread of bumblebees (Bombus terrestris), insect pollinators very useful in the pollination of flowers of the tomato, which has in fact canceled the use of hormones alleganti of chemical origin.
This acceleration in the production process has somehow forced the Sicilian farmers to greater care and control of environmental parameters of the crops (temperature, humidity, etc..) And also ensure the maximum health of the production.
The cultivation of table tomatoes in Sicily is located in the provinces of Ragusa and Trapani. In Ragusa growing particularly interested in the municipalities of Pachino, Victoria, Scicli and Achates.
In the Trapani area of cultivation is known to Marsala. The success factors are determined by the quality of the tomato and the typical production. The most important example is the area of Pachino, where sandy soils and dry soils irrigated with brackish waters have made the miracle, ensuring the highest quality productions. Nowadays, the common saying, do not mention the most cultivated varieties but there is talk of "Pachino tomato" or even "Pachino" to locate the production in that area.
The varietal aspect is crucial for development. Types grown in this area in particular the type “Marmand”, which is collected as a single fruit at veraison and that is the green maturation. Thanks to the use of brackish water to meet crop water requirements are obtained with good fruit size and high consistency, that allows high strength and excellent aging potential for transport to the bench. The high salinity also characterizes the appearance of the berry, which assumes the typical dark green color intensity. The production model was further developed with the introduction of grape varieties and the "cherry tomato" or “little cherry”. Commercial development of this tomato is particularly due to the spread of cultivar “Naomi”, selected in Israel through a genetic improvement project that also saw the use of Italian germplasm. Today, new varieties were introduced and new types, but the success is also linked to the recovery of old cultivars such as "Cuore di Bue” (heart of the ox). This area was also one of the first that has capitalized on its territory and its production through the acquisition from Union European of the Protected Geographical Indication.

Tomato varieties for table or fresh market
Types of tomatoes in Italy and the elements that distinguish the Italian range of varieties, contrary to what happens in other countries, traditional producers of tomatoes for fresh consumption (Spain) or in those recently calling (Netherlands, Belgium), are attributable to a greater diversity in shape, size, pigmentation, and development. A fragmentation varietal capable of ensuring a wide and varied but may come at the expense of commercial development and concentration of supply.
It is impossible to describe all the types present at the national level, often very similar, however you can stop on the old local ecotypes currently in the market as a valuable niche products: The quality characteristics of table tomatoes are related to morphological characteristics (shape and size, intensity and color uniformity), structural characteristics (thickness of the peel and mesocarp, amount of seeds), chemical characteristics (sugar content, acids, mineral salts , vitamins, lycopene) and organoleptic characteristics (intensity of flavor, texture and digestibility). Favorite fruits are usually of medium to large, deep red, with or without collettatura, with few seeds and thin skin. Very important are the characters that relate to the product's shelf life after harvest. In particular, in recent years have been developed cultivar, named with the acronymus LSL (Long Shelf Life), fruits with high consistency particularly appreciated by the market, but sometimes too fibrous and difficult to digest if harvested immature. In addition to the above characteristics of the fruit, the cultivar used in greenhouses should submit the following requirements: reduced vegetative growth, early production, resistance to cold and disease. The disease resistance is particularly important in the context of integrated production because it can help resolve specific problems of parasitic character without resorting to expensive soil disinfection methods as well as not environmentally friendly.
Le principali caratteristiche minime di qualità sono le seguenti, distinte per tipologia varietale:

Varieties for fresh market
Varieties for salsa
Cluster Varieties
In relation to the types indicated, are now represented in some hybrids and varieties of tomato garden, table, tableware, from direct consumption, some of them can also be used for processing, preferably made in the family, but also industrial.


Raccolta meccanica del pomodoro da industria
La raccolta ormai viene fatta meccanicamente con l’utilizzo di macchine trainate o semoventi. La scelta del mezzo viene fatta in base ad alcuni fattori: l'organizzazione aziendale, la pedologia del terreno, la valutazione economica e la qualità del prodotto.
Di solito, le aziende di media ampiezza acquistano macchine trainate, mentre i controterzisti e le grandi aziende acquistano quelle semoventi.
In Italia sono presenti le principali ditte costruttrici di macchine da raccolta.
A partire dagli anni 70 si è andata sempre più diffondendosi la raccolta meccanica del pomodoro da industria. Le prime macchine effettivamente funzionali sono da ricondursi a Guaresi. Ovviamente si trattava di macchine trainate con cernita manuale del prodotto. Indicativamente occorrevano almeno 8 persone solo per la cernita. A questi vanno aggiunti l’autista del trattore che trainava la macchina. Devono passare ancora parecchi anni prima che facciano capolino le prime selezionatrici elettroniche, che permettevano di alleviare molto l’onere di monodopera per la cernita del prodotto. Questa è stato la vera innovazione che ha poi spinto alla realizzazione di macchine semoventi, permettendo rese molto più elevate ed in tempi fino ad ora impensabili.
In seguito il perfezionamento delle selezionatrici, l’abbinamento di più elementi ottici in linea, l’aggiunta di altri dispositivi elettronici per la gestione della macchina, hanno portato alle macchina attuali.
Funzionamento di una macchina raccoglitrice. Possiamo dividere il lavoro svolto dalla raccoglitrice in 3 grandi settori:
1) la raccolta della pianta e del prodotto dal suolo;
2) il distacco delle bacche dalla pianta;
3) la cernita del prodotto per l’allontanamento delle bacche verdi, marce e comunque del prodotto non conforme (compreso quindi foglie, terra, sassi, vegetazione).
La pianta viene raccolta dal pick up (in Italia principalmente è un pick up a denti, ma è possibile trovare in altre realtà modelli a falcetto o a dischi) e tramite un nastro trasportatore viene inviata al battitore. L'azione vibrante dei raggi porta al distacco delle bacche che per gravità cadono sul nastro, mentre un altro nastro porta la vegetazione residua nella parte posteriore della macchina, dove una ventola provvede ad allontanarla in senso opposto all’avanzamento. Il flusso d’aria generato colpisce la “cascata” di prodotto nel salto tra due nastri, eliminando così le foglie e la vegetazione che inevitabilmente si sono staccate durante la trebbiatura.
A questo punto il prodotto, tramite un nastro trasversale posteriore, subisce "un cambio di direzione" ritornando quindi in direzione anteriore. Viene quindi immesso sul nastro di pre-cernita dove, a seconda del numero di selettori elettronici, subirà una decisa pulitura. Successivamente al nastro cernita, il prodotto viene immesso sul nastro di cernita manuale dove 1-2 o più operatori (a seconda delle situazioni) affina la pulitura del prodotto. Generalmente è necessario un’operatore anche nella parte posteriore della macchina, prima della cernita, in modo che possa intercettare corpi estranei che potrebbero danneggiare la selezionatrice. A volte questo è il solo operatore, più ovviamente il conducente.
Affinchè la cernita sia efficace, il nastro di precernita deve essere perfettamente in piano. A seconda delle scelte costruttive delle varie case, possiamo avere un livellamento automatico del solo nastro, oppure dell'intera macchina. Nel primo caso il livellamento riguarda solo il verso trasversale, nel secondo sempre quello trasversale riferito però alla macchina intera. Quest’ultima scelta è stata ormai adottata da quasi tutti i costruttori ed alcuni propongono un'ulteriore bilanciamento longitudinale dei nastri di cernita. Il tutto allo scopo di mettere le selezionatrici nelle condizioni migliori per effettuare il loro lavoro.
La resa attuale di queste macchine si aggira tranquillamente sui 1000 q/ha. Infine, il nastro di scarico provvede a scaricare il pomodoro su bins o altri contenitori atti al trasporto. Questo è un punto critico della macchina. Si viene a creare un vero e proprio collo di bottiglia. Ovvero tutta la macchina è in grado di sostenere una certa resa, ma il nastro di scarico non è altrettanto performante, dovendo così rallentare la velocità di raccolta.
A tal proposito si sono cercate delle innovazioni che, applicate nelle macchine recenti hanno brillantemente risolto alcune problematiche. Essenzialmente il “pick-up elettronico” e lo “sterratore elettronico”. Il primo è un dispositivo che serve ad automatizzare la regolazione dell’altezza del pickup di raccolta. Sicuramente sulle macchine grosse, sia per la raccolta a fila singola, sia per la raccolta a fila binata, occorre puntare sulla velocità di raccolta. Con questo dispositivo è facile mantenere gli 8-9 Km/h. Il secondo è un accoppiata nastro e selezionatore elettronico per la sola separazione di terra e sassi.
Importanti sono alcune considerazioni su selezionatrici, sterratore e pickup elettronico. Nel caso delle selezionatrici, alcune case costruttrici offrono oggi la possibilità di montare fino a 3 elementi selezionatori. Questo fatto di dover montare sull macchina fino 3 selezionatori costringe a rivalutare le scelte agronomiche. Non si può ottenere una raccolta meccanica con una percentuale di verde tanto alta da dover richiedere una "forza selezionatrice" così elevata.
Nel caso dello sterratore quello proposto è presentato come la soluzione per la raccolta in caso di terreno bagnato. Questo è effettivamente un problema molto importante, ma si presenta solo in suoli argillosi. In presenza di tessiture pesanti lo sterratore non può essere di molta utilità. Infatti, l’intasamento delle stanghe dei nastri non è provocato da zolle di terra che risalgono i nastri della macchina, ma da continui apporti di terra e fango proveniente dalle radici delle piante sollevate dai denti del pick-up. Lo sterratore serve per le zolle, non per il fango. Inoltre è proposto come soluzione per i terreni sassosi, ma in un contesto attuale, moderno e razionale, andare a coltivare pomodoro su terreno sassoso, tale da rendere problematica la raccolta, non è la scelta ottimale.
Riguardo al “pickup elettronico”, questo è sicuramente utile sull’asciutto. Da valutare l’efficacia sul bagnato, anche se va detto che con l’ausilio dei rulli motorizzati sotto al pickup, in situazioni normali, diventa praticamente inutile. Forse sarebbe meglio curare meglio la sarchiatura e la sistemazione del terreno, piuttosto che incorrere in costosi e complicati sistemi elettronici.
Sono ora riportati alcuni modelli idonei per la raccolta meccanica del pomodoro:
La raccoglitrice MTS base è fornita di una selezionatrice elettronica Protec Color Sorter 2000 che viene costantemente migliorata nelle caratteristiche ottiche e nel software di gestione al fine di ottimizzare le modalità d’intervento del gruppo d’espulsione. Le raccoglitrici in base ai modelli montano selezionatrici a 30, 40, 50 canali. Queste apparecchiature possono vedere difetti e colori dei frutti, indipendentemente dal momento della giornata in cui si opera (soprattutto all’alba e al tramonto), grazie al sistema antiabbagliamento automatico ad integrazione digitale. Di questa macchina sono note alcune versioni: