[Physiological responses of Salix rehderiana and Populus cathayana grafted seedlings to nitrogen deficiency]. / å·æ»‡æŸ³ä¸Žé’æ¨å±žé—´å«æŽ¥å¹¼è‹—å¯¹æ°®ç´ ç¼ºä¹çš„ç”Ÿç†å“åº”.

ABSTRACT

Morphological and physiological responses of Salix plants are different from Populus to nitrogen (N) deficiency. In this study, grafting technology was used in S. rehderiana and P. cathayana to investigate the graft compatibility of Salix and Populus, and whether grafting could improve the resistance to N deficiency in Salicaceae plants. The survival rate, growth, biomass accumulation and allocation, gas exchange parameters and non-structural carbohydrates (NSCs) were measured to evaluate the resistance to N deficiency among different grafting combinations. The results showed that the graft compatibility between S. rehderiana and P. cathayana was quite high. The survival rate was 74% and 96% in S/P (S. rehderiana was used as scions and P. cathayana as rootstocks) and P/S (P. cathayana was used as scions and S. rehderiana as rootstocks) combinations, respectively. N deficiency reduced the survival rate in all grafting combinations, which were 53.3% and 86.7% in S/P and P/S, respectively. The survival rate of S/P was lower than that of the other grafting combinations. Under control and N-deficient conditions, the height, basal diameter, biomass and net photosynthetic rate (Pn) of P/P and P/S combinations were higher than those of S/S and S/P combinations. N deficiency significantly reduced growth rate, biomass accumulation and Pn in all grafting combinations. The rate between root biomass and aboveground biomass of S. rehderiana rootstock combinations (S/S and P/S) was significantly higher than those of P. catha-yana rootstock combinations (P/P and S/P) under both control and N-deficient conditions. It indicated that more photosynthates might be allocated to belowground in S. rehderiana, while to aboveground in P. cathayana. The NSCs in roots of all grafting combinations were more sensitive to N deficiency than in stems and leaves. Except for the S/P combination, the starch, fructose, sucrose and total soluble sugar concentrations were significantly increased in roots in P/P, S/S and P/S combinations. Additionally, under N-deficient condition, the NSCs contents were significantly higher in P/P and P/S combinations than in S/S and S/P combinations.