Combined Effects of Ozone and Nitrogen on Secondary Compounds, Amino Acids, and Aphid Performance in Scots Pine

Abstract

AbstractCombined effects of O3 and N supply on Scots pine (Pinus sylvestris L.) were studied in two separate growth chamber experiments exposing seedlings to 0, 0.075, 0.15, and 0.3 µL/L of O3 during 8 h/d, 5 d/wk for a period of 5 wk. Seedlings were fertilized with low, medium, and high levels of N. Ozone and N availability affected concentrations of several primary and secondary metabolites. More changes on metabolites were detected in Exp. 1 (with seedlings ceasing their annual growth) than in Exp. 2 (with seedlings actively growing). Overall, high O3 exposure levels significantly decreased concentrations of monoterpenes and increased concentrations of resin acids. Concentrations of total phenolics were not affected by O3 exposure. Mostly lower concentrations of monoterpenes and resin acids were found at a medium N‐fertilization level than at low and high N‐fertilization levels, while total phenolic concentration decreased by enhanced N availability. In Exp. 1, significantly elevated concentrations of free amino acids were found at O3 concentration of 0.3 µL/L. Nitrogen availability did not have remarkable effects on amino acid concentrations. In Exp. 1, both O3 and N had a significant effect on the MRGR of the aphid Schizolachnus pineti. In Exp. 2, the weight of the females and nymphs and the total number of reproduced nymphs were significantly affected by O3 and N. Only a few interaction effects were found, suggesting that the N supply does not significantly modify O3‐induced effects on studied primary and secondary compounds and aphid performance in Scots pine seedlings.