Responses of ‘Burlat’ Sweet Cherry Trees to Selenium Fertilisation under Low Soil Selenium Conditions

Selenium (Se) malnutrition in humans primarily results from low soil Se availability. In this study, we examined the effects of soil application and preharvest Se sprays on the vegetative growth, yield response, Se nutrition, and fruit quality of ‘Burlat’ sweet cherry (Prunus avium L.) trees. Selenium was applied through (i) soil application at a rate of 250 g ha− 1 or 500 g ha− 1 in each season and in the first year of the study, respectively, and (ii) four preharvest sprays per season at a rate of 15 g ha− 1 spray− 1. Se sprays were applied with or without calcium chloride (CaCl2). Leaves from Se-fertilised trees contained more Se and had enhanced SPAD readings. However, the Se treatments did not affect tree growth and fruit yield. Compared to the control fruit, Se concentrations in fruit from trees sprayed with Se and CaCl2, trees sprayed with Se alone, and trees supplied with Se to the soil were increased 15-, 12-, and 8-fold, respectively. None of the Se treatments affected fruit size, and acidity and the soluble solids concentration (SSC) of the fruit. Only the combined sprays of Se and CaCl2 decreased the incidence of rain-induced fruit cracking. None of the tested Se treatments resulted in leaf injuries. In sweet cherry orchards, at least for the ‘Burlat’ variety, grown in low Se soils, preharvest Se sprays with or without CaCl2 can be recommended to biofortify the fruit with Se and increase SSC in the fruit.