[Evaluation of drought-resistant physiological characteristics of roots and leaves for main greening tree species in Northwest Liaoning Province, China in spring.]

In the present study, the effects of spring drought stress on physiological characteristics of leaves and roots for Populus alba, Ulmus pumila, Syringa oblata and Prunus sibirica were analyzed in Northwest Liaoning Province. The relationships between leaves and roots under drought stress were explored, and drought resistance of the four tree species was evaluated with the method of subordinate function and the gray correlative analysis. The results showed that there were significant differences in osmotic substances contents (soluble sugar, soluble protein and proline), antioxidative enzymes activities (SOD, POD and CAT) and malondialdehyde content among the four tree species and different organs (leaves and roots) (P<0.05). The average subordinative value in leaves increased in a sequence of P. sibirica (0.245), P. alba (0.346), S. oblata (0.412) and U. pumila (0.673), but it increased in roots in an order of U. pumila (0.315), P. sibirica (0.383), S. oblata (0.552) and P. alba (0.558). Meanwhile, the average subordinative value in leaves of P. alba, S. oblata and P. sibirica was lower than in roots, but it was higher in leaves than in roots of U. pumila. The association between physiological indexes and drought resistance showed an order of malondialdehyde > SOD > CAT > soluble protein > proline > soluble sugar > POD in leaves, and an order of malondialdehyde > soluble protein > soluble sugar > CAT > POD > proline > SOD in roots. These results indicated that the drought-resistant capability was different in leaves and roots of the four tree species. The roles of drought-resistance indexes were different between leaves and roots of the four tree species. Different management measures should be selected according to different organs of various tree species.