Year-to-year Variations in Antioxidant Components of High-Lycopene Tomato (Solanum lycopersicum L.) Breeding Lines

Abstract

A two-year field study (2013−2014) was performed to evaluate phytochemical content and antioxidant activity of two high-lycopene tomato breeding lines (HLT-F71 and HLT-F72) grown under open field conditions as compared to the traditional cultivar (cv) Rio Grande. Two open-field trials were conducted in 2013 and 2014. Three tomato cvs were used: two high-lycopene tomato advanced breeding lines (HLT-F71 and ‘HLT-F72’) (F7 generation), and the open-pollinated cv Rio Grande commonly grown in Tunisia. Regardless the growing years and cvs, lycopene content ranged from 98.8 to 280.0 mg/kg fw, total phenolics from 176.1 to 831.8 mg GAE/kg fw flavonoids from 169.7 to 552.1 mg RE/kg fw and total vitamin C from 183.4 to 370.0 mg/kg fw. Significant year-to-year variability was only detected in total phenolics and flavonoid content. No significant year-to-year variability in antioxidant activity was detected in high-lycopene lines. Disregarding the cv, tomato berries harvested on July 2014 had 143% - 224% higher total phenolics and 8% to 47% higher flavonoid contents compared to tomato berries harvested on July 2013. However, disregarding the cv, tomato berries harvested on July 2013 had 6% -17% higher lycopene and 8% -21% higher LAA compared to berries harvested on 2014. During the second growing year, the higher temperature, particularly prior to harvest, determined a decrease in lycopene content and a significant increase in total phenolics regardless the cv. Although the huge variability in total phenolics and the decrease in lycopene content during the second harvest, the antioxidant activity was not affected by year-to-year variability. This reveals consistent functional quality of these cvs and minimal genotype*environmental conditions interaction.