Round Tomatoes Research Articles

Series del Manejo de Vegetales en Florida – Tipos de Tomate Roma y Redondo

Revised! HS1073, an 11-page illustrated fact sheet by Steven A. Sargent, Jeffrey K. Brecht, Teresa Olczyk and Elena Lon Kan, focuses on effective techniques for post-harvest handling of Roma and round tomatoes. Includes references. Published by the UF Department of Horticultural Sciences, November 2006.

TAMI G GRAPE TOMATO RESPONSE TO NITROGEN RATES

Grape tomatoes (Lycopersicon esculentum Mill.) have recently gained in popularity among consumers because they can be eaten without being cut, they are deep red in color, and their flavor is intense and pleasant. Current N fertilization recommendations have been developed for determinate tomato varieties that have a 3-month long growing season, whereas that of the indeterminate grape cultivars may be up to six months. 'Tami G' grape tomatoes (previously identified as a suitable alternative to 'Santa') were grown on a Lakeland fine sand at the North Florida Research and Education Center-Suwannee Valley, near Live Oak, FL in the Spring of 2005 using standard plasticulture practices under 0%, 33%, 66%, 100%, 133%, and 166% of the current recommended rate for round tomato (224 kg/ha). Tomatoes were transplanted 24 Mar. and harvested, weighed and graded five times between 10 June and 15 July. Soluble solid concentrations (SSC) were also measured at each harvest. Season marketable (SMY, kg/ha) and total yield (TY, kg/ha) response to N rates were quadratic (SMY = -0.16 Nrate 2 + 140 Nrate + 11,821 R 2 =0.56; CV=32%; TY = -0.18 Nrate2 + 153 Nrate + 13949; R 2 =0.54, CV=32%; both p<0.01). Highest SMY and TY occurred between 314 and 392 kg/ha N rates. N rate effect on SMY and TY was significant only for harvest 4 and 5. SSC ranged from 6.25 to 7.5°Brix for harvests 1 to 4 and was not significantly affected by N rate. On harvest 5, SSC tended to be greater with higher N rates. These preliminary results suggest that N fertilization for grape tomato could be done by incorporating 56 to 78 kg/ha of N in the bed, followed by daily rates ranging from 0.5 to 3.5 kg/ha/day. Because the length of the growing season for grape tomato may vary, emphasis should be placed on daily N rates and irrigation management, rather than on seasonal N rate.

EFFECT OF THE VARIETY AND GROWING METHODS AS WELL AS CULTIVATION CONDITIONS ON THE COMPOSITION OF TOMATO (LYCOPERSICON LYCOPERSICUM (L.) KARSTEN) FRUIT

Tomato is one of the most extensively cultivated horticultural crops in the world. Quality factors such as size, firmness, colour, taste, and nutritional content are important criteria for marketing of tomato fruit. The aim of the present study was to evaluate the effects of different varieties (18), cultivation technologies (forcing, open-field with supporting system, open-field with processing varieties) and the connected ecological conditions on the composition of tomato fruit. We have measured the soluble solids (°Brix), carbohydrate, organic acid, lycopene and ascorbic acid contents. These parameters determine the flavour and quality of tomato fruits. The average soluble solids content ranged from 5.2 to 8.7 %. The highest °Brix was observed in the fruits of Favorita (8.7 %, cherry type). Carbohydrate contents constitute nearly 50% of the °Brix. The highest carbohydrate content was observed for Favorita and Cheresita 8 (cherry type) whereas the lowest was detected in Falcorosso. Low acid content was found for Nivo and Delphine Fl cultivars. The sugar acid ratio was 40% higher in the case of the cherry types than that of the other varieties. Average lycopene content of examined tomato varieties was extremely diverse (47.7 133.6 mg.kg -1 ). Ascorbic acid levels ranged from 226 to 381 mg.kg -1 . In case of open-field cultivation with supporting systems, cherry type varieties showed significantly higher °Brix and carbohydrate content than varieties of round tomato type with average fruit weight of 100-130 g. All varieties examined produced significantly higher organic acid contents in forcing as compared to the values of round tomato varieties cultivated in open-fields with supporting systems and processing varieties. Lycopene content was significantly higher in processing varieties.

Changes in Antioxidant Content of Tomato Fruits in Response to Cultivar and Nutrient Solution Composition

The aim of this study was to investigate the effect of cationic proportions (K/Ca/Mg) in the nutrient solution on fruit quality (quality attributes and antioxidant content) using a high-pigment, 'Lunarossa', tomato cultivar and a standard tomato cultivar ('Corfù') grown in soilless culture. Treatments were defined by a factorial combination of three nutrient solutions having different cationic proportions and two indeterminately growing round tomato cultivars. A high proportion of K in the nutrient solution increased the quality attributes (fruit dry matter, total soluble solids content) and the lycopene content of tomato fruit, whereas a high proportion of Ca improved tomato fruit yield and reduced the incidence of blossom-end rot (BER). The highest total antioxidant activity was observed in the treatment with a high proportion of Mg in the Lunarossa cultivar. The high-pigment hybrid has provided a higher antioxidant content (lycopene and alpha-tocopherol content) than the commercial hybrid, but it was more susceptible to BER and consequently less productive.

Effects of genotype and cultivation environment on lycopene content in red‐ripe tomatoes

AbstractLycopene, a natural red pigment found in tomato, is correlated with reduced incidence of some cancers. Forty tomato varieties, including cluster F1 hybrid tomatoes, round breeding line tomatoes (Lycopersicon esculentum Mill) and cherry tomato types (L esculentum var cerasiforme), grown under greenhouse and field conditions were evaluated for their lycopene content using high‐performance liquid chromatography (HPLC) and spectrophotometry. Lycopene content varied significantly among the tomato varieties, with cherry tomato types having the highest lycopene content. Greenhouse‐grown cluster and round tomatoes contained more lycopene (mean = 30.3 mg kg−1) than field‐grown tomatoes (mean = 25.2 mg kg−1), whereas cherry tomato types had a higher lycopene content in field‐grown (mean = 91.9 mg kg−1) than in greenhouse‐grown (mean = 56.1 mg kg−1) fruits. HPLC analysis of lycopene isomeric forms revealed a higher content of all‐trans isomers in all tomato genotypes examined. However, the cis isomeric form was exceptionally higher in the field‐ and greenhouse‐grown cherry tomato L esculentum var cerasiforme cv Gardener's Delight, which contained ∼9.3 and 9.9 mg kg−1 cis isomers respectively. Results indicate that genetics and choice of cultivation environment may have a strong influence on tomato lycopene content. Copyright © 2005 Society of Chemical Industry

Padrão de identidade e qualidade do tomate (Lycopersicon esculentum Mill.) de mesa

O valor comercial do tomate, Lycopersicon esculentum Mill., é definido pelas características de identidade e qualidade presentes no fruto que podem ser avaliadas pela classificação do produto. A presente revisão de literatura teve como objetivo descrever o padrão de identidade e qualidade do tomate de mesa, através da classificação. O tomate de mesa é classificado em grupos, subgrupos, classes e tipos. De acordo com o formato do fruto, o tomate é classificado em dois grupos: oblongo, quando o diâmetro longitudinal é maior que o transversal e redondo, quando o diâmetro longitudinal é menor ou igual ao transversal. Em função do estádio de maturação, o tomate é classificado em cinco subgrupos: verde maduro, pintado, rosado, vermelho e vermelho maduro. A classe é definida em função do maior diâmetro transversal do fruto em relação ao grupo a que pertença. O tomate oblongo é classificado em três classes: grande, médio e pequeno. O tomate redondo é classificado em quatro classes: gigante, grande, médio e pequeno. De acordo com os índices de ocorrência de defeitos graves e leves presentes nos frutos, o tomate é classificado também em tipo: extra, especial ou selecionado e comercial. São considerados defeitos graves: podridão, passado, queimado, dano por geada, podridão apical, e defeitos leves: dano, mancha, ocado, deformado e imaturo. A amostra de tomate que ultrapasse os índices de defeitos previstos pela legislação do Ministério da Agricultura é classificada como fora do padrão.

Antioxidant activity and general fruit characteristics in different ecotypes of Corbarini small tomatoes.

Sixteen ecotypes of Corbarini small tomatoes were studied. The antioxidant activity was evaluated with the DMPD (N, N-dimethyl-p-phenylenediamine) method in the water-soluble fraction (S-AA) and with the ABTS [2, 2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)] method in the water-insoluble fraction (I-AA). S-AA and I-AA were strongly related to each other, varying to a large extent between the ecotypes considered. They were also significantly correlated with fruit weight, total solids, and refractive index. The combination of the latter variables (by multiple regression analysis) accounted for 36% and 44% of the total variability of S-AA and I-AA, respectively. Moreover, when the ecotypes were subdivided according to their shape (round, pear-shaped, oval, and long), S-AA and I-AA were both significantly higher in round tomatoes and lower in the long ones. In conclusion, the antioxidant activity varies to a considerable extent between different ecotypes of Corbarini small tomatoes. These differences are related to shape and some other fruit characteristics.

Sensory analysis, sugar and acid content of tomato at different EC values of the nutrient solution

The influence of three concentrations of nutrient solution (electrical conductivity, EC: 1.0, 3.5 and 6.0 dS m −1) on the sensory properties of tomato was investigated. Two tomato cultivars representing two types—a conventional round tomato (cv. Counter) and a round longlife tomato (cv. Vanessa)—were harvested from a closed hydroponic system with recirculating nutrient solution. The same products were investigated by quantitative descriptive analysis with trained panellists and by an acceptance test with consumers. Furthermore, the contents of reducing sugars and the titratable acid of fruits were analysed. To find explanations for consumer preferences relationships between the results of quantitative descriptive analysis, consumer acceptance tests and the sugar and acid contents of the fruits were investigated. The quantitative descriptive analysis revealed changing intensities of sensory attributes of appearance, firmness by touch, flavour, aftertaste and mouthfeel with increasing nutrient solution EC. However, the change of different sensory attributes was different for the two cultivars. Intensity of unfavourable flavour attributes such as mouldy, spoiled sweetish and bitter was stronger only for the longlife cultivar when cultivated at high EC. Higher EC values resulted in higher contents of reducing sugars and titratable acid, which influenced the intensity of several sensory attributes of smell, flavour and aftertaste evaluated by the descriptive panel. Consumers preferred the flavour from those fruits of both cultivars that were cultivated at EC 3.5 dS m −1. Acceptance in the characteristics flavour, aftertaste and mouthfeel of fruits of the longlife cultivar grown at EC 6.0 dS m −1 was diminished. There were significant correlations between the results of the hedonic consumer assessment of the products and the quantitative descriptive analysis, which could contribute to explain preferences. In most cases, the sensory changes caused by increasing nutrient solution EC from 1.0 to 6.0 dS m −1 improved the quality of the conventional round cultivar but not that of the longlife one.

Dry-matter partitioning in a tomato crop: Comparison of two simulation models

SUMMARYTOMSIM(l.O) and TOMGRO(I.O) are two dynamic models for tomato growth and development. Their sub-models for dry-matter distribution between leaves, stem and fruits were compared and discussed. In both models the simulated dry-matter distribution is regulated by the relative sink strengths of the plant organs. These sink strengths are quantified by the potential growth rates of individual organs, i.e. the growth rates under conditions of non-limiting assimilate supply. This approach is general and not limited to the tomato crop. In TOMGRO(J.O), fruits, leaves and internodes stay within age classes and move from class to class during development, whereas in TOMSIM (1.0), record is kept of every fruit truss separately but leaves and internodes are lumped together (i.e. no record of weight or leaf area per age class as in TOMGRO(l.O)). In TOMSIM(1.0), vegetative sink strength is a constant, whereas in TOMGRO(l.0) it is calculated from potential area expansion rate of leaves and specific leaf area. In both models, the ratio between leaf growth and stem growth is constant. In TOMGRO(l.O) there is a feed-back mechanism which controls the vegetative/generative balance: a higher demand/supply ratio for assimilates induces higher fruit abortion rates. In TOMSIM(l.O) the number of fruits set per truss is not simulated, but is an input to the model. TOM SIM (1.0) functions representing flowering rate, fruit growth period, vegetative sink strength and fruit sink strength were compared with similar TOMGRO(l.O) functions, in their dependence on temperature and physiological plant age. A sensitivity analysis was made for the effects of temperature, flowering rate, and fruit and vegetative sink strengths on dry-matter distribution for both models. A validation of both models was based upon periodic destructive harvests in: 1) a greenhouse experiment in Wageningen, using a round tomato cultivar, consisting of a control treatment and a treatment where every second truss was removed at anthesis, and 2) two greenhouse experiments conducted in Montfavet, using a beefsteak tomato cultivar. Daily shoot dry-weight increase, average 24 h greenhouse temperatures and numbers of fruits set per truss (in TOMGRO(l.O) numbers of flowers per truss) were inputs to the models. In general dry-matter distribution was simulated well by both models for the cultivar and conditions where they were developed. TOMGRO(1.0)'s poor performance in one of the validations resulted from the absence of an assimilate storage pool. To achieve reasonable agreement between measurements and simulations for situations other than where the models were developed, parameter adjustments had to be made, most likely reflecting cultivar differences. Strong and weak points of both models are discussed.