SUMMARY OF THE PHD THESIS

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1 SUMMARY OF THE PHD THESIS Tomatoes originate from Central and South America, Peru and Ecuador, the original species being Lycopersicon esculentum var. cerasiforme which has been used in Mexico since 200 BC. The origin centre of tomatoes is found around Vera Cruz and Pueblo settlements, being known hundreds of years before America was discovered. They were reported by Christopher Columbus in 1498, but were considered to be ornamental plants for many years (CIOFU et al., 2004). These vegetables are cultivated for their fruits, which are consumed freshly, as salads or preserved. They represent raw material for can factories, being used for juice preparation, tomato paste and other sorts of food. They posses a high nutritive value due to the vitamins, carbohydrates, minerals, amino-acids and organic acids that they contain (BERAR et al., 2012, GIORGOTA and LAURENŢIU, 2010). Tomatoes are herbal, annual plants, in our climate conditions. In the areas of their origin, with tropical and sub-equatorial climate, the plants are perennials (INDREA et al., 2009; POPESCU, 1996; POPESCU and ATANASIU, 2000; POŞTA, 2008). Tomato's root is pivoting, the main pivot being able to penetrate 2-3 meters in light soils. The stem is herbal, with an erected position only during the first part of vegetation. Subsequently it falls on the ground due to the heavy weight of leaves and fruits, needing a supporting system (CIOFU et al., 2004). It easily emits adventitious roots in contact with moist soil. Therefore, the seedling can be planted deeper, while the elongated ones are planted in a recumbent position. The leaves are compound, with leaflets of different sizes, alternatively placed. The leaflets are oval, lanceolate, with whole or toothed edges and smooth or corrugated surface, according to variety. The entire leaf is covered by glandular trichomes that release a specific smell when touched (BUTNARIU, 1970; BUTNARIU et al., 1992). The inflorescence is of cyme type and appears on the interval between leaves (on the internode); the flower is of type 5. The petals are yellow and are overgrown at the base with the corolla's tube, while the anthers are united, forming a cone 263

2 that covers the pistil. Usually, the pistil is shorter than the stamens. The pollen falls on the stigma as the flower opens, resulting in an autogamous pollination (CIOFU et al., 2004; MUNTEANU, 2001; STAN and MUNTEANU, 2001). The fruit is a fleshy berry, actually being an enlarged ovary with two or several locules that contain seeds (fertilized ovules), included in a gelatinous placenta (PAPADOPOULOS, 1991), of different shapes, colors and sizes, according to the cultivated variety or hybrid. The fruit color may be red (of different shades), orange, yellow, pink, etc. Their size is usually evaluated by weight and varies within very large limits, from g to g and even 800 g, according to variety and cultivation technology. The cherry tomatoes have small fruits, weighing only a few grams (APAHIDEAN and APAHIDEAN, 2004). Tomatoes grow and fructify normally under environmental conditions similar to those where they were formed. They are thermophile, heliophile and hygrophyle plants, exigent to mineral nutrition (INDREA et al., 2007): The optimum growth and fructification temperature is o C during daytime and o C at night. Light is the most important factor that affects greenhouse tomato production. The off season limited amount of light may reduce production significantly, despite inflorescence and flower formation, as fertilization does not take place, and therefore the fruits are not produced (PAPADOPOULOS, 1991; PAPADOPOULOS and PARARAJASINGHAM, 1997). The minimum level of light intensity is 5-6 klx, while the optimum is situated above 20 klx. The most favourable daylight duration is of hours; continuous light produces degenerative phenomena (BERAR, 1998; HORGOŞ 2000). Although plants have a relatively high water consumption, l/day/plant, according to age, and a middle perspiration coefficient ( ), the water demands of tomatoes can be considered as moderate. The mineral nutrition of tomatoes presents various peculiarities which have to be taken into consideration for fertilization. Thus, the specific consumption is variable, according to the culture system, variety, production and mineral supply of soil (INDREA et al., 2007; BĂRBAT and CALANCEA, 1970). 264

3 The average texture soils are recommended for tomatoes. The sandy soils are recommended for early cultures, if nutritive elements and water are provided. The clayey soils are not suitable for tomato culture (CIOFU et al.; 2004). The human consumption necessities, that require the daily dietary intake of vegetables, especially fresh but also processed, determined the current production to adopt various culture systems. These systems aim mainly at staging production throughout the whole year (INDREA and APAHIDEAN, 1995; INDREA and APAHIDEAN, 1997). From this point of view, our country performs: field cultures (free), forced cultures and protected cultures, in greenhouses and polyethylene tunnels. The "soilless" culture systems appeared and extended from the necessity to overcome the drawbacks that soil represents as culture support: unsuitable ratio between the solid part, water and air, the "soil fatigue" phenomena caused by the phytosanitary status, as well as nutritional imbalances that occur in soils that are intensely cultivated with the same species of plants (INDREA et al., 2007, STAN and STAN, 2010). One of the main soilless culture advantages is that it avoids the decrease of natural soil fertility (VERDONCK, 1975). Beside that, several diseases or pests can be avoided, as they are specific for field cultures (TZORTZAKIS and ECONOMAKIS, 2008). The soilless greenhouse cultures can represent an alternative to classical culture systems, for vegetables with high nutritional value, including tomatoes. The greenhouse vegetables can be cultivated on different soilless substrates, as long as they provide a proper irrigation and fertilization (CANTLIFFE et al., 2003). very good results were obtained when tomatoes were cultivated on mixed substrates, made up of peat, perlite and bark of conifers (CANTLIFFE et al., 2003; BOHME, 1995; MALOUPA et al., 2001). The purpose of the research covered by the present PhD thesis is to improve various aspects of greenhouse tomato cultivation technology, cycle I on organic substrate, using cheap and easily accessible materials, aiming at obtaining large early and total productions, with lower specific costs, as compared to other soilless or classical soil culture systems. The objectives pursued in order to accomplish the desired goal were: study of greenhouse tomatoes behaviour in soilless culture, as compared to the classical culture in greenhouse soil; 265

4 study of a foreign hybrid behaviour in organic substrate culture system, in the greenhouse soil as well as in polyethylene bags; establishment of culture substrate composition, using organic materials (peat, long duration follow soil, well decomposed manure); study of different fertilization recipes, in order to establish the optimum nutrient quantities, needed to improve the productive potential; adaptation of cycle I greenhouse tomato culture technology to the peculiarities of soilless culture system, by establishing the best methods for plant support, by managing irrigation and fertilization regime; Other aspects of culture system that were followed: the microclimate evolution in substrate bags as well as in the greenhouse; the evolution of chemical composition of organic substrate throughout cultivation; the evolution of mineral supply stage of greenhouse soil, for comparative cultures of tomato hybrids in soil and organic substrate; plant growth and fructification; production dynamics; early and total production; fruit quality; culture economic efficiency indexes. The experiences were polyfactorial, made up of four experimental factors, with corresponding graduations each: Biological material: Cronos F1 and Menhir F1 hybrids; Culture system: greenhouse soil culture and soilless culture, in polyethylene bags on organic substrate (80% peat and 20% long duration follow soil mixed with well decomposed manure); Basic fertilization: performed with simple fertilizer dose (Complex III 300 kg/ha N:P:K 15:15:15 for soil culture and Complex III 3 kg/m 3 for bag culture) as well as with double fertilizer dose (Complex III 300 kg/ha + Multicote 4 N:P:K

5 kg/ha 15:7:15 + ME (microelements) for soil culture and Complex III 3 kg/m 3 + Multicote 4, 3 kg/m 3 for bag culture); Supplementary fertilization: radicular (1% Complex III 15:15:15, once every 2 weeks) and radicular + foliar (radicular fertilization + 0,5% Ferticare 10:5:26, once every 7-10 days). Through the combination of the four factors, a total of 16 experimental variants resulted, that were arranged in 4 repetitions each. Conclusions on the results obtained in 2006 The Menhir hybrid, cultivated in bags, with double fertilization dose + foliar fertilization yielded plants with highest average height, with most leaves and inflorescences, also achieving the highest flower fertilization percentage. The highest production volume was harvested during the first decade of June, and the lowest in April. The highest extra quality fruit percentage was recorded for Cronos hybrid, cultivated in bags, with simple + foliar fertilization, while the highest extra + 1st quality fruit percentage was recorded for Menhir hybrid, cultivated in bags, with double + foliar fertilization. The unilateral influence of experimental factors showed that significantly higher productions can be obtained by performing bag cultures and using the Menhir hybrid, while the combined influence of those factors revealed that maximum production, of 125t/ha, was obtained for Menhir hybrid, cultivated in bags, with double + foliar fertilization. Conclusions on the results obtained in 2007 The bag culture provided a more vigorous growth of plants, these variants yielding high values of plant height, leaf number and inflorescences. They also showed significantly higher fertilization percentages. 267

6 The harvesting dynamics revealed that the highest fruit percentage was obtained in June, followed by May and July, while the lowest amount of fruits was harvested during the third decade of April. Although for soil culture, the simple dose of fertilizers provide more extra quality fruits, for bag culture, the double doses and phaseal fertilizations produce the same effect. The extra + 1st quality fruit percentage is above 90% for all variants. Early production was positively influenced by bag cultivation, as compared to soil cultivation, by using the Menhir hybrid as compared to Cronos and by performing foliar fertilization. As far as the total production is concerned, very significant statistical differences were recorded for bag cultivation, as compared to the classical culture system, for the Menhir hybrid, for using double fertilization doses and performing phaseal fertilizations. The highest production recorder for 2007, of t/ha was recorded for Menhir hybrid, cultivated in bags, by applying double fertilization doses and phaseal fertilizations. Conclusions on the results obtained in 2008 As far as growth and fructification is concerned, the Menhir hybrid showed taller plants, as compared to Cronos, the foliar fertilization having a positive effect on leaf and inflorescence number. The highest flower fertilization percentage was recorded for Menhir hybrid, when double dose of fertilizers was used, together with foliar fertilization, while the lowest was recorded for Cronos, cultivated in bags, when simple fertilizer doses were applied together with foliar fertilization. The highest production, of t/ha was recorded when Menhir hybrid was cultivated in bags, with double dose of fertilizers and foliar fertilization, which also yielded the highest quantity of extra fruits ( t/ha), followed by Cronos, cultivated under the same conditions (133.5 t/ha), whic also yielded the highest percentage of extra quality fruits (86.74%). The lowest production, of t/ha, was recorded for Cronos hybrid, cultivated in bags, with simple dose of fertilizer. 268

7 The highest amount of fruits were harvested in May, followed by June, July and April. The unilateral influence of the experimental factors on early production showed that the soil cultures yielded higher productions, the Menhir hybrid showing a higher productivity than Cronos, the application of double fertilization doses and foliar fertilizations having the same effect. For total production, very significant positive differences were recorded for bag cultivation, when the Menhir hybrid was used and where double fertilizer doses were combined with foliar fertilization. Conclusions on average experimental results obtained between The unilateral factor influence on average early production recorded between showed very significant positive differences obtained for bag cultures as compared to soil culture, when Menhir versus Cronos hybrid was used, and when foliar fertilization was applied, while the application of double fertilizer doses also provided a distinctly significant positive production difference. Just like early production, the total production also showed statistically significant production differences, for the unilateral influence of all factors. Thus, very significant positive differences were recorded for the cultivation system (in favour of bag cultivation system), and fertilizer dose applied (in favour of double dose and phaseal fertilization), while a distinctly significant positive difference was recorded for the hybrid used, the Menhir hybrid having a higher total average production then the Cronos hybrid. The highest total average production obtained between was recorded for the Menhir Hybrid, cultivated in bags, with a double dose of fertilizer and foliar fertilization. Conclusions on soil analyses Following the analyses performed in order to evaluate soil humidity at the beginning of cultivation, in 2006, an average soil humidity of 29.95% in mass percentages was obtained. 269

8 The greenhouse soil showed an excess of nitrogen, as compared to bag culture, which is commonly seen in greenhouses due to the levigation phenomenon. The other elements were all within normal limits, except Ca, which was situated at the lower limit for bag cultures, although supplementary calcium nitrate fertilizations were performed every 2 weeks, in order to prevent apical fruit rot. Conclusions regarding qualitative determinations performed on tomato fruits The largest dry soluble substance accumulations were noticed for PE bags cultivation variants, with high doses of radicular and foliar fertilizers. The content of nutritive elements in fruits that belonged to soil cultivated variants was situated within normal or lower than optimum limits, while those belonging to bag cultivated tomatoes, on organic substrate, with radicular and foliar fertilization, showed higher values for Na, K, Fe, Mn and Zn (much higher than optimum) which was correlated with higher productions obtained for this culture system. The amount of vitamin C in fruits varied, especially according to culture system used: in fruits obtained after soil cultivation, the vitamin C content was lower, unlike PE bag cultivation. The maximum amount of vitamin C was of mg/100g s.p. The acidity determinations from tomato fruits show that this parameter is greatly influenced by biological material as well as cultivation and fertilization system used. The variants where high fertilization doses were used also showed an increased fruit acidity, as did the Menhir hybrid and the fruits obtained from bag cultures, as compared to classical culture system. The most important recommendations of this PhD thesis are as follows: Obtaining vigorous and tall plants, with a high number of leaves, inflorescences and fruits is possible through cultivation of plants in PE bags, together with radicular and foliar fertilizations. If sowing, pricking out and culture establishment times are respected, as presented in the thesis, large productions can be obtained at the end of May, beginning of June, when there is a deficit of tomatoes on the market, and the selling price is high; 270

9 In order to obtain high productions, the classical culture system should be replaced with PE bags, while fertilization should be performed with high amounts of radicular and foliar fertilizers; The Menhir hybrid presented a higher productivity, with an increased percentage of extra fruits, as compared to Cronos; the fruits also showed a higher nutritional value, which recommends its use for cultivation; In order to obtain fruits that posses a high dry matter, vitamin C and acidity content, we recommend PE bag cultivation versus greenhouse soil cultivation. 271