Strategy of Ginkgo biloba L. in the mitigation of salt stress in the urban environment

Abstract

Abstract Ginkgo biloba is recommended in street plantings in many countries due to its resistance to urban conditions. Our research confirmed the relatively low sensitivity of G. biloba to unfavorable urban conditions salt stress. The research consisted of two field experiments with urban trees and a controlled potted experiment with young trees. There was a large diversity of reactions between the older street trees and the young trees from the pot experiment. In both experiments, the leaves demonstrated high values of Cl and Na. The street tree leaves contained an average of 1.13% Cl and 1061\u2009mg\u2009kg−1 Na. In the pot experiment, depending on the NaCl dose, the Cl content ranged from 0.07% to 4.80%, and Na ranged from 40.4\u2009mg \u2009kg−1 to 7953\u2009mg \u2009kg−1. The street tree leaves did not have any damage, and in the pot experiment, the first measurable damage to the leaves appeared with leaf Cl and Na contents of 2.42% Cl and 4.86\u2009mg\u2009kg−1 Na. The health conditions of the leaves, even at the highest levels of Cl and Na, were not bad (damage index of 2.4 on a six-point scale). In urban conditions, an increasing amount of Cl was accompanied by an increase in polyprenols in the leaves. In the model experiment, there was no increase in the content of these compounds with a concomitant increase in the NaCl dose. The G. biloba strategy may rely on the ability to synthesize polyprenols acquired during the process of adaptation. This ability was only possessed by older street trees; young trees in the pot experiment did not develop this ability.