Effect of variety and grafting on lycopene content of ...

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Jul 29, 2008 - ketchup, sauce, and salsa. Lycopene is responsible for ... Tomato plant is a major vegetable where grafting is important worldwide (LEE, 2003).
Acta Alimentaria, Vol. 38 (1), pp. 27–34 (2009) DOI: 10.1556/AAlim.2008.0013 First published online 29 July 2008

EFFECT OF VARIETY AND GRAFTING ON LYCOPENE CONTENT OF TOMATO (LYCOPERSICON LYCOPERSICUM L. KARSTEN) FRUIT L. HELYESa*, A. LUGASIb, Á. POGONYIa and Z. PÉKa a Department

of Horticultural Technology, Szent István University, H-2103 Gödöllő, Páter K. utca 1. Hungary Institute for Food Safety and Nutrition, H-1097 Budapest, Gyáli út 3/a. Hungary

b National

(Received: 16 April 2007; accepted: 17 March 2008)

Lycopene, found primarily in tomatoes, is a member of the carotenoid family and has potent antioxidant capability. The aims of the present study were: 1) to investigate the effect of grafting on lycopene content of tomatoes and 2) to evaluate the effects of different varieties on lycopene content (open-field with supporting-system, open-field with processing varieties) under the same ecological conditions. The effect of grafting on lycopene content was analysed in the case of two varieties, between the years 2001 and 2003. Lycopene content of tomato fruits decreased significantly by grafting. Ten commercial varieties of tomato produced in Hungary were examined for their lycopene content. Lycopene content of tomato turned out to be extremely diverse, and variable (63.0–155.0 mg/kg fresh weight). It was found that the variety of tomato is one of the most important determinants of lycopene content. Keywords: biotic factors, variety, grafted plant, lycopene, tomato

Tomato is an important agricultural commodity worldwide. More than 80% of tomatoes is consumed in the form of processed products such as tomato juice, paste, puree, ketchup, sauce, and salsa. Lycopene is responsible for the characteristic deep-red color of ripe tomato fruits and tomato products. It is the major carotenoid in tomato representing 80–90% of the total pigments in it. Tomatoes and tomato products are the major dietary sources of lycopene, but other foods such as watermelon, pink grapefruit and guava (CLINTON, 1998) can compensate the dietary intake of lycopene. Lycopene is correlated with reduced incidence of some cancer types. It is an acyclic, biologically active carotenoid found in foods, and its preventive role in several cancerous diseases has been proved by epidemiological and experimental data (LUGASI * To whom correspondence should be addressed. Phone: 36-28-522-071; fax: 36-28-420-804; e-mail: [email protected] 0139-3006/$ 20.00 © 2008 Akadémiai Kiadó, Budapest

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et al., 2004). The exact optimum intake of lycopene is unknown; however, men in the Harvard study with the greatest protection against cancer consumed at least 6.5 mg/day (GIOVANNUCCI et al., 1995; KANETSKY et al., 1998). In plant cells, the lycopene molecule is an intermediate of the biosynthesis of betacarotene. All-trans-lycopene is the predominant isomer in fresh tomatoes, but processing leads to the formation of the all-cis isomer, which can account for 35–96% of total lycopene in various tomato-based products (STAHL & SIES, 1996). During processing, a large part of trans-lycopene transforms into cis-lycopene (TAKEOKA et al., 2001). The use of grafted seedlings has become more and more widespread in several parts of the world. Grafted seedlings are commonly used in commercial vegetable cultures in countries such as Korea and Japan, where the percentage of cultivated area of grafted seedlings in outdoor vegetable culture amounts to 81% and 54%, respectively (LEE, 1994). There are several advantages of grafting such as low or high temperature tolerance, salt tolerance, extended harvest period, earliness and increase of yield (LEE & ODA, 2003; POGONYI et al., 2005). Tomato plant is a major vegetable where grafting is important worldwide (LEE, 2003). Soluble solids, ascorbic acid and total soluble sugar content have been found higher in ungrafted tomato plants than those in grafted ones (CHUNG et al., 1997; POGONYI et al., 2005), LOPEZ-GALARZA and co-workers (2004) found lower total solube solids and sugar concentrations in grafted watermelon. Fruits from the synthetic cytokinin-treated tomato plants had also a weaker red colour than fruits set by pollination. However, if tomato plants are grown under saline conditions, salinity increased soluble solids such as glucose and fructose will increase significantly in grafted plants. Concentrations of lycopene have not been affected by salinity, but a significant increase due to grafting has been observed (FERNANDEZ-GARCIA et al., 2004). Antioxidant content of tomatoes depend on genetics, environmental factors (temperature, light, water and nutrient availability), agricultural techniques (varieties, plant growth regulators, harvesting date) and on post-harvest storage conditions (MARTÍNEZ-VALVERDE et al., 2002; DUMAS et al., 2003). According to BRANDT and coworkers (2003) significantly higher lycopene content was observed in glasshousegrown tomatoes (83.0 mg kg–1 f.w.) than in field-grown fruits (59.2 mg kg–1 f.w.) at different harvesting times. Lycopene content is mainly determined by the genetics of the variety being grown (ABUSHITA et al., 2000; HELYES et al., 2003; GIUNTINI et al., 2005). The values ranged from 3.93 to 17.1 mg/100 g lycopene content with variations ranging from more than one to fourfold in lycopene (HELYES et al., 2003). According to KUTI and KONORU (2005) lycopene content varied significantly among the tomato varieties, with cherry tomato types having the highest lycopene content. Greenhousegrown cluster and round tomatoes contained more lycopene than field-grown tomatoes. The main target of the series of measurements was to determine the effects of grafting and cultivars on lycopene content of tomato fruits.

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1. Materials and methods 1.1. Plant material The grafting experiments were conducted in the experimental station of Szent István University, Gödöllő in spring greenhouse forcing beetwen 2001–2003. Tomato varieties were Daniela F1 (in 2001) and Lemance F1 (in 2002 and 2003) as scion was grafted to Beaufort (Lycopersicon esculentum × L. hirsutum interspecific hybrid) rootstock. Date of sowing was January 20th, and date of planting to the greenhouse was March 25th. Plant density was 2.1 plants/m2. The distance between the rows was 1.2 m and the distance between the plants was 0.4 m in the rows. Plants were arranged in four repetitions. Fruit samples were harvested on 21st June. There are hundreds of varieties of tomatoes, including large “beefsteak” type, Italian plum tomatoes, called Roma type, globe, square round, oblong-cylindrical (ideal for processing), pear- and egg-shaped, small, cherry tomatoes etc. Naturally, red tomatoes are most common, these vegetables can also be yellow, green, pink or orange. In 2001, we used five processing varieties (determined growth-type varieties) in one part of open-field experiment (Early Fire, Bonus, Falcorosso, Korall and Nívó). In the other part of our open-field experiments, supporting-system was used. Here five indeterminate varieties (Fanny F1, Thomas F1, Delfine F1, Daniela F1 and Cheresita (cherry tomato)) were examined. In 2002, we examined only one processing variety (Falcorosso) and we investigated three indeterminate varieties on the supporting-system: Delfine F1, Daniela F1 (round type) and Cheresita (cherry type). The main parameters of tomato plant introduction are shown in Table 1. During the growing season all cultivation procedures (nutrition supply, irrigation and plant protection) were conducted according to technological expectations. Table 1. The main parameters of tomato plant introduction Years Actions Date of sowing Date of planting out Plant density (pl./m2) Date of harvest

Determinated varieties 30.03. 11.05. 3.7 29.08.

2001 Indeterminated varieties 30.03. 08.05. 2.1 29.08.

Determinated varieties 28.03. 15.05. 3.7 21.08.

2002 Indeterminated varieties 28.03. 12.05. 2.1 21.08.

1.2. Sampling and analysis At least 5–6 fruits from each repetition were washed, cut, and mixed using a homogenizer (PT 3100; Kinematica Inc., Newark, N.J.) and the juice samples were stored at –18 °C until analysis. Lycopene from homogenised tomato was extracted with n-hexane-methanol-acetone (2:1:1) mixture containing 0.05% BHT. Water-free Na2SO4

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was used to remove water traces of the upper part. Optical density of the hexane extract was measured spectrophotometrically at 500 nm against hexane blank (SADLER et al., 1990) by UV-VIS Spectrophotometer Lambda 3B (Perkin Elmer). Concentration of lycopene was calculated using the specific extinction coefficient (E1cm1% 3150) (MERCK, 1989). Experiments was executed in four repetitions, and the results were expressed as average ± standard error of average of repetitions. One- and two-way analyses of variance (ANOVA) were used to determine significant differences between tomatoes using Microsoft Excel 2003. 2. Results and discussion Lycopene content of fruits from ungrafted and grafted tomato plants harvested on the 21 st of June during three years of greenhouse experiments are shown in Fig. 1. Processing the data with two-way analysis of variance, it was established that neither year nor variety affected the lycopene content of fruits. Contrary to the results of FERNANDEZ-GARCIA and co-workers (2004), in our experiment, grafting caused a significant (23.5% on average; P