The Effect of Foliar Spray Fertilizers on the Tolerance of Hordeum vulgare to UV-B Radiation and Drought Stress

The impact of foliar spray fertilizers (Aton Az) on the resistance of spring barley (Hordeum vulgare L.) against to individual and combined UV-B radiation and drought effects were investigated. Barley seeds were sown in pots prepared with neutral pH peat substrate. When the 2nd true leaf unfolded, i.e. 7 days after germination, the first spray with microelement and free amino acid fertilizers was carried out; two days after this application, the different irradiation (1 and 3 kJm–2 d–1) UV-B doses and drought effects were started. Exposure lasted for 6 days. The main characteristics of all investigated indicators were assessed at the end of exposure. The largest positive effects of fertilizers on the photosynthetic rate and water use efficiency of barley were found solely under the impact of drought. Foliar spray fertilizers decreased oxidative stress injury in the leaves by decreasing the malondialdehyde content under solely effects of drought and UV-B radiation, while under the combined effect of the mentioned stress factors, the changes were statistically insignificant. A stronger positive impact of foliar fertilization was detected on the content of photosynthetic pigments (a and b) at solely UV-B radiation effect than at combined effect of investigated factors, when significant changes were detected only in individual cases.