The tomato plant
Tomato plants are vines, initially decumbent, typically growing 180 cm (6 ft) or more above the ground if supported, although erect bush varieties have been bred, generally 100 cm (3 ft) tall or shorter. Indeterminate types are “tender” perennials.
Solanaceae Juss. Lycopersicon lycopersicum (L.) Fawell. (Lycopersicon esculentum Mill)The tomato plant
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.
Tomato vines are typically pubescent, meaning covered with fine short hairs.
Tomato fruit is classified as a berry. 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. For propagation, the seeds need to come from a mature fruit, and be dried or fermented before germination. (https://en.wikipedia.org/wiki/Tomato)
It is a cultivation that can take several years, although usually lasts a tear. It is an herbaceous plant with a wide root system between 50-60 cm deep. There is a principal root from where many ramifications start.
The stem is angular and covered with perfectly visible short hair. Much of this hair has a glandular origin and gives a characteristic smell to the plant. At the beginning they are erect plants, but when they are tall and heavy they creep.
Most tomato plants have compound leaves, and are called regular leaf (RL) plants. The leaves are 10–25 cm (4–10 in) long, odd pinnate, with five to 9 leaflets on petioles, each leaflet up to 8 cm (3 in) long, with a serrated margin; both the stem and leaves are densely glandular-hairy. Their flowers, appearing on the apical meristem, have the anthers fused along the edges, forming a column surrounding the pistil‘s style. Flowers in domestic cultivars tend to be self-fertilizing. The flowers are 1–2 cm (0.4–0.8 in) across, yellow, with five pointed lobes on the corolla; they are borne in a cyme of three to 12 together.
The tomato plant does not need of photoperiod to form flowers, however it determines the vegetal growth.
The increase of the vegetal growth is promoted by luminosity and temperature. The optimal growth is obtained with a day temperature of 23 degrees centigrade and 17 degrees centigrade at night.
Some studies seem to demonstrate that the harvest date was inverse related with the illumination in the seeding phase, and that the weight of the fruits was related with the quantity of illumination during production.
There is a great amount of substances that allow us to control many characteristics of the development of the plant. Some of those substances will let us control the fundamental aspects as the uniformity of the plantation, stimulation of the roots, advance or delay the grafting, to get early crops, increase the number of flowers or influence the curdle of fruits.
The application of auxins is an example. It is a substance that stimulates the development of the seed, and creates a parthenocarpic development of the fruit.
The application of low temperatures in the air system delays the opening of the first flowers. Besides, in relation with temperatures, the number of flowers per inflorescence raises with temperatures between 12-15 degrees centigrade remaining invariable from 15 degrees until 30 degrees.
Temperature, light and humidity play an important role in order to produce a correct formation of pollen that could pollinate a great amount of flowers.
In usual very early conditions on the Spanish Mediterranean coast is very usual to have adverse environmental conditions to create a normal fertilisation and curdle of the fruits.
Besides the application of the growth regulators to obtain the best results in curdle, techniques of mechanic agitation and vibrators are used with the intention of getting more pollen with the shakings. Another new technique is the use of bumblebees hives (Bombus terrestris L.)
Biological or agronomic cycle
The more frequent cycles of cultivation in Spain are divided in the following groups:
Very early cycle: The seedbed is made from October to do the grafting in December. This cycle is cultivated in a greenhouse. The harvest takes place from February. It is very usual in the South-East of Spain.
Early cycle: Seeding is made at the end of November, mid December in protected seedbeds. The grafting takes place at the beginning of February outdoors, protecting the lines of cultivation with any method. The harvest starts mid May. It is a typical cycle used Valencia.
Normal cycle: seeding at the end of January in protected seedbeds. The grafting takes place outdoors in no frost times. The harvest, depending on the cultivation zone and varieties, is distributed along summer. This cycle is usually used in inner zones and in tomato plantations destined for industry.
Late cycle: Seeding in July and June outdoors. Grafting takes place in July and September and the production is staggered between mid September and the end of February.