Antioxidant content and ascorbate metabolism in cherry tomato exocarp in relation to temperature and solar radiation

Abstract

Considering the economic importance of the tomato and its nutritional benefits to human health, a study was made of how two different environmental factors (temperature and overall solar radiation) influence the nutritional quality of cherry tomatoes during the plant full production cycle. Solanum lycopersicum L. cv. Naomi plants were grown in an experimental greenhouse. Three fruit samples were taken over the full production period: first sampling at the beginning of harvest (7 January 2004), second at mid-harvest (22 March 2004) and third at harvest end (30 May 2004). Values for temperature and overall accumulated solar radiation peaked at a maximum in the third sampling, without lowering the yield with respect to previous samplings. Regarding the antioxidant activity in the exocarp fraction of the cherry tomato fruits, the results showed that the increase in temperature and solar radiation diminished the lycopene and β-carotene contents in the third sampling, inducing defective pigmentation (sunscald). This occurred simultaneously with an increase in lipid peroxidation during the third sampling, quantified as lipoxygenase activity and malondialdehyde content. Finally, in relation to ascorbate metabolism, the higher temperatures and stronger solar radiation at the third sampling increased the oxidation of reduced ascorbate (AsA) due to intensified ascorbate peroxidase (APX) and ascorbate oxidase (AO) activities and a depression of the enzyme dehydroascorbate reductase (DHAR). In conclusion, the results indicate that despite the oxidation of AsA by APX and AO, the minimal regeneration of the latter, together with the greater lipid peroxidation with increasing temperature and solar radiation in the greenhouse, explained the lower content of antioxidants in the exocarp and therefore the loss of nutritional quality of the cherry tomato fruits grown under these conditions.

Effects of Salt and Water Stress on Plant Growth and on Accumulation of Osmolytes and Antioxidant Compounds in Cherry Tomato

“…A clear symptom of oxidative damage is cell membrane degradation; therefore, MDA -a product of membrane lipid peroxidation -is an excellent marker of oxidative stress (Del Rio et al, 1996). In this study a significant increase of MDA levels in tomato leaves upon salt and water stress treatments of the plants was obseved, in agreement with previous reports showing a salt-induced increase of MDA contents in tomato leaves (Shalata and Thal, 1998), roots (Shalata et al, 2001) and fruits (Rosales et al, 2006).…”

The Effect of Potassium Biofortification Over Yield and Nutritional Quality of Cherry Tomato Fruits

“…One of the most characteristic phytonutrients in tomato fruit, Lyc represents roughly 80% of all carotenoids and has a high capacity to eliminate ROS (Rao et al, 1998). Many studies have demonstrated a strong relation between the nutritional quality of tomato and its Lyc content (Constán-Aguilar et al, 2014; Rosales et al, 2006). Also, K significantly affects the concentration of such pigments as Lyc and β-carotene, which can be used as inner-quality indicators for tomato, based on analytical and sensorial properties (Ramí rez et al, 2012).…”

“…These results appear to agree with those of the present study at 24 and 29 WAT (Table 3) (Figs. 1 A and 2 A, 2B), as the decline in the lycopene content could be due to the oxidation of this compound to β-carotene; however, β-carotene degradation also intensifies from 35 to 40ºC (Rosales et al, 2006;Gautier et al, 2005).…”

Cherry tomato yield in greenhouses with different plastic covers

“…Air temperature reduction is one of the tomato greenhouses main objectives (ROSALES et al, 2006), since elevated temperatures resulted from high light intensity can severely limit productivity and nutritional quality of this crop (ADAMS et al, 2001). To this end, shading screens are the most used option (SERRANO et al, 2001), principally the thermoreflective screens, which have the ability to reduce the sensible heat accumulated inside the greenhouses by the incident solar radiation reflection (GUISELINI et al, 2010).…”