Impact of different selenium doses on leaf gas exchange of the underutilized leafy green Portulaca oleracea grown hydroponically

Selenium (Se) is an essential micronutrient crucial for properly functioning the human immune, endocrine, and reproductive systems. To combat Se deficiency, an innovative and sustainable approach known as Se-biofortification has emerged. This cost-effective strategy involves increasing the Se concentration in edible plant parts or products, thereby improving the nutritional status of the global population. Underutilized leafy greens, characterized by their high nutritional value and resilience to adverse climatic conditions, offer great potential in this context. Despite not being commercially grown or widely consumed, these leafy vegetables can serve as an excellent vehicle for Se-biofortification. Taking all these factors into consideration, an experiment was carried out in the greenhouse facilities of the Laboratory of Vegetable Production at the Agricultural University of Athens, aiming to appraise the impact of Se dosage (0, 2, 4 μmol L-1) on photosynthetic attributes of an underutilized leafy vegetable. The plant species used in this experiment was Portulaca oleracea, which was grown hydroponically using perlite as substrate, while Se was applied through the nutrient solution by incorporating SeO2 into it. For the light response curves of the photosynthetic rate (A), transpiration rate (E), stomatal conductance (Gs), and intercellular CO2 concentration (Ci), the youngest fully expanded leaves were placed inside the chamber of LCpro T (ADC) and irradiated with 0, 87 348, 696, 1044 µmol m-2 s-1. The obtained results clearly indicate that applying Se at a dosage of 2 μmol L-1 can be an effective method for improving the nutritional value of Portulaca oleracea without compromising the photosynthetic apparatus of this underutilized leafy green. This method could be implemented in countries where the consumption of these crops is widespread, but their nutritional value is low due to the soil conditions. In addition, this study could be useful for future research on the biofortification of underutilized crops and for improving global nutrition.