Foliar application of selenium and nano-selenium affects pomegranate (Punica granatum cv. Malase Saveh) fruit yield and quality

Abstract

This study examined the impact of selenium (Se) (added as Na2SeO4) and Se nanoparticles (N-Se), as a foliar spray, on several growth parameters, mineral content of leaves, yield, physical and biochemical characteristics of pomegranate (Punica granatum L. cv. Malase Saveh). The experiment was conducted over two consecutive years in the northwest of Iran. Se and N-Se were applied once in 2016 and once in 2017 at 1 and 2 μM (Se1 and Se2, N-Se1 and N-Se2, respectively), first at the full-bloom stage and then one month later. Control plants were sprayed with Se-free water. N-Se2 significantly increased the following parameters in the first year (2016) and second year (2017), respectively: leaf area (1.22- and 1.25-fold), chlorophyll content (1.34- and 1.24-fold), number of fruits/tree (1.35- and 1.28-fold), peel thickness (1.33- and 1.27-fold), fruit diameter (1.08- and 1.10-fold), and yield (1.17- and 1.16-fold). N-Se2 significantly increased N (1.23- and 1.22-fold), P (1.36- and 1.44-fold), K (1.08- and 1.11-fold), Ca (1.12- and 1.17-fold), Fe (1.15- and 1.18-fold) and Se (3.33- and 3.25-fold) content in leaves in both years while Zn content was higher after N-Se2 (1.03- and 1.07-fold) and Se1 (1.02- and 1.04-fold) treatments in both years. N-Se2 significantly increased, relative to the control and in the first and second year, respectively, total sugars (1.17- and 1.19-fold), the content of phenolic compounds (1.05- and 1.08-fold), antioxidants (1.23- and 1.25-fold), and anthocyanins (1.23- and 1.27-fold). Se and N-Se treatments enhanced maturity index and decreased fruit cracking. Broadly, our results indicate that a high concentration of N-Se has a greater and more beneficial impact than a low concentration. Future experiments should focus on increasing the concentration of N-Se. These findings can assist in pomegranate fruit production in arid regions.