# Effect of foliar sodium selenite fertilization on oxidative stress and productivity in Olea europaea L., biofortification and quality of extra virgin olive oil

## TL;DR

This study explores how applying sodium selenite to olive trees affects their stress resistance and the quality of olive oil, finding limited impact on oil selenium content.

## Contribution

The study provides new insights into the effects of foliar selenium fertilization on olive tree physiology and olive oil quality.

## Key findings

- Sodium selenite increased selenium levels in leaves but not significantly in olive oil.
- Lower reactive oxygen species levels were observed in leaves treated with specific selenium doses.
- Selenium application showed mixed antioxidant and pro-oxidant effects over time.

## Abstract

Fertilization of plants with selenium (Se) can enhance their resistance to abiotic stresses and improve human health and nutrition. However, Se fertilization in olive trees remains underexplored. This study evaluated the effect of foliar sodium selenite fertilization on leaf Se content, oxidative stress, olive tree productivity, biofortification of extra virgin olive oils (EVOO), and their physicochemical and antioxidant attributes in two mature ‘Arbequina’ olive orchards.

Although Se application did not affect fruit productivity, Se doses were related directly to total Se content in leaves. A slight increase in Se levels in EVOO was observed at the highest dose of sodium selenite applied. Lower levels of reactive oxygen species (ROS) were observed in leaves fertilized with 150 and 100 mg Se dm−3, after the first and second application, respectively. Application of Se had no clear effect on the physicochemical quality of olive oil or its antioxidant properties.

Selenium application was effective in increasing Se concentration in leaves; however, it proved insufficient to enhance Se content in EVOO. Sodium selenite at the applied doses influenced oxidative stress parameters, exhibiting both antioxidant and pro‐oxidant effects over time. © 2025 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.