Functional, Flavor and Visual Traits of Hydroponically Produced Tomato Fruit in Relation to Substrate, Plant Training System and Harvesting Time

Christos Mitsanis,Theologos Koufakis,Dimitrios Gerasopoulos,Athanasios Koukounaras,Danai Christina Aktsoglou,Pavlos Tsouvaltzis,Anastasios S. Siomos

doi:10.3390/horticulturae7090311

Christos Mitsanis, Theologos Koufakis + Show 5 more

Open Access

https://doi.org/10.3390/horticulturae7090311

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Journal: Horticulturae	Publication Date: Sep 14, 2021
Citations: 6	License type: CC BY 4.0

Affiliation: Aristotle University of Thessaloniki

Abstract

Currently, a great portion of tomatoes is produced by soilless cultivation systems and the substrate selection among the various materials is one of the most important factors affecting yield and quality traits. On the other hand, grafting has been successfully used in soilless systems to ensure long-term cultivation. However, due to the high cost of grafted seedlings, plant training systems are sought. Given the fact that most literature refers to studies intended to mainly reveal production differences among treatments and the quality aspect was secondary, the present study was focused on the evaluation of tomato fruit functionality, flavor and visual traits. Tomato plants cv ‘Beef Bang F1’ were cultivated in a glasshouse hydroponic culture in four substrates: rockwool slabs, perlite in sacks, pumice in sacks and pumice in 9 L pots. The type of cultivated plants used were self-rooted or grafted onto ‘Defensor’ trained in single and double stems. Tomato fruit were harvested three times during the season (6 June, 31 July, 6 November). The fruit quality was measured based on visual (average fruit mass, and Minolta color values), flavor (dry mass, soluble solids content, titratable acidity, pH, flesh firmness) as well as functional traits (total phenolic content, ascorbic acid, lycopene, β-carotene, total carotenoid content and antioxidant capacity). Harvest time was the most important factor followed in many of these cases by the substrate (flavor and functional traits), as well as in certain cases by the plant grafting/training (flavor traits and antioxidants) or by both in some flavor traits and antioxidants. Correlation of color values with lycopene, though significant, was weak. Each individual harvest time revealed the rise in different parameters. Pumice, whether used in pot or in sack, enhanced the visual and flavor attributes the most, self-rooted plants and mid-summer harvest resulted in the highest tomato fruit quality.

Highlights

Tomato fruit is considered the most popular vegetable among consumers worldwide because of its availability throughout the year and its richness in beneficial for human health phytochemicals such as carotenoids, vitamin C and phenolics, all possessing antioxidant capacity [1,2,3,4,5,6]
Analysis of variance indicated that visual (Table 1), flavor (Table 2) and functional traits (Table 3) were predominantly influenced by the harvest date factor, since most of the variation accounted for this factor; a visual trait (L*) or some flavor ones, such as dry matter (DM)
The substrate factor influenced total soluble solid content (TSS), TSS/titratable acidity (TA), Flesh firmness (FF) and functional traits except β-CAR, but the variation accounted for was between 19.0 and 15.3% for TSS and total antioxidant capacity (TAC), respectively, while the variation accounted for other parameters was below 10.5%

Summary

Introduction

Tomato fruit is considered the most popular vegetable among consumers worldwide because of its availability throughout the year and its richness in beneficial for human health phytochemicals such as carotenoids (lycopene and β-carotene), vitamin C and phenolics, all possessing antioxidant capacity [1,2,3,4,5,6]. Tomato fruit antioxidants have been reported to contribute to protection of free radicals which are considered as risk factors in the development of cancer and cardiovascular diseases [7]; based on fresh tomato fruit antioxidant potential, they have been proposed to be termed a “functional food” [8,9] and the nutritional quality traits can be referred to as functional. Tomato fruit phytochemical content is affected by different biotic and abiotic factors, such as cultivar, production system, plant grafting and training techniques, harvest ma-. A great portion of tomatoes is produced by soilless cultivation systems which ensures high yields and quality production. The soilless production system is known to provide a soilborne disease-free environment as well as proper nutrition-irrigation according to the needs of the plants. In soilless production systems the substrate type is considered among the most important factors affecting yield and quality of greenhouse grown vegetables [14]

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