Enhancing the content of biologically active components in cluster tomatoes using organic fertilizers

Abstract

Tomatoes (Solanum lycopersicum L.) are a vital agricultural crop with significant nutritional value, attributed to their high content of vitamins, minerals, and antioxidants. The antioxidant properties of tomatoes contribute to reducing the risk of cardiovascular and oncological diseases, positioning them as an important component of a balanced diet and beneficial for public health. The application of organic fertilizers containing fulvic and humic acids is particularly relevant to ensure the production of high-quality and nutritious tomatoes. These compounds, recognized as bio stimulants in plant cultivation, enhance physiological processes in plant cells. They stimulate protein and nucleic acid synthesis, activate enzymatic activity, and regulate metabolic pathways, thereby improving the biochemical composition of tomato fruits, increasing their nutritional quality, and enriching the content of bioactive compounds.

The objective of this study is to evaluate the accumulation of bioactive compounds such as lycopene, total phenols, vitamin C, total sugars, and dry matter in cluster tomato fruits using an Armenian fertilizer containing fulvic and humic acids. Additionally, the research aims to provide practical insights into sustainable agriculture by identifying optimal agronomic practices that enhance the accumulation of these bioactive compounds in cluster tomatoes. The research was conducted on greenhouse-grown cluster tomato hybrids: Syune F1 (Armenian breeding), Prodezo F1 (Rijk Zwaan), Santiano F1 (Rijk Zwaan), Adventure F1 (Rijk Zwaan), and Climbo F1 (Syngenta) during the spring growing seasons from the years 2022 to 2024. The experiment utilized an organic fertilizer, and applied by abiding the following treatment scheme: 1. Control (St) — no organic fertilizer application, 2. Root treatment (RT), 3. Foliar treatment (FT), 4. Combined root and foliar treatment (RT-FT). Biochemical analyses of the tomato fruits were performed to quantify lycopene, total phenols, ascorbic acid, and total sugars using spectrophotometry, while dry matter content was determined via refractometry. Statistical data analysis was conducted using analysis of variance (ANOVA).

The study demonstrated that all treatment types with fulvic-humic fertilizer contributed to improving tomato fruit quality and the accumulation of biologically active components. The most effective treatment was the combined root and foliar application (RT-FT), which resulted in the highest values across all measured parameters. Depending on the hybrid, lycopene content increased by 11.1–15.9%, total phenols by 14.7–22.8%, when vitamin C by 13.1–15.9%, total sugars by 13.5–21.7%, and dry matter by 14.6–22.5% compared to the control. The 'Syune' and 'Climbo' hybrids exhibited the highest accumulation of lycopene and phenols, highlighting their potential for enhancing antioxidant properties. The 'Santiana' and 'Adventure' hybrids were notable for their elevated ascorbic acid content, making them particularly valuable for improving nutritional quality. The best results for sugar and dry matter accumulation were observed in the 'Syune' and 'Prodezo' hybrids, indicating improved flavor profiles in these tomato varieties.

Keywords:  tomatoes, lycopene, total phenols, ascorbic acids, total sugars, dry matter, organic fertilizer, fulvic acids, humic acids