Abstract:

Protective enzyme（SOD、POD、CAT）,osmotic solut（Pro）,MDA, the protoplasmic membrane penetrability and the leaves water content of four stocks grafted seedlings of Catalpa bungei cl.‘Yu 1’ were studied on drought tolerance by natural drought way. The result showed: in the condition of drought stress, the protective enzymes（SOD、POD、CAT）activity of four kinds of grafted seedlings of C. bungeicl.‘Yu1’ showed the trend of risingdeclining. The protective enzyme activity of seedlings with C. bungeias stocks was higher than the other three kinds of seedlings, and SOD of which had obvious difference(P<0.05) with grafted seedlings with C. ovata. The content of praline of all seedlings showed trend ascended at first and then descending. The MDA content and the protoplasmic membrane penetrability of different grafted seedlings take on a tendency which increased continually, and changing tendency was consistent. The leaves water content of the four grafted seedlings went down. The drought tolerance of the four kinds of graftedseedlings is in the order that grafted seedlings with C. bungei> grafted seedlings with self> grafted seedlings with C. ovata > grafted seedlings with C. fargesii using subordinate function values and which had extremely significant difference between grafted seedlings with C. bungei and other seedlings(P<0.01).

Key words: Catalpa bungei cl.‘Yu1’, stocks, graft, drought tolerance, physiological response