Physiological and biochemical changes during graft union formation in Carya illinoinensis

To reveal the physiological and biochemical mechanism underlying graft union formation in pecan (Carya illinoinensis), dynamic changes content of nutrients, tannin, phytohormones together with key enzyme activities were investigated 0, 3, 5, 7, 10, 14, 18, 22, 31, 40 d after grafting (DAG), homograft unions. During formation, peroxidase (POD) activity increased at 7 - 10 DAG compared that 0 DAG. Polyphenol oxidase (PPO) was higher grafted than ungrafted seedlings (control) 22 DAG, which similar to POD activity. The tannin exhibited a decreasing trend relative control. Indole-3-acetic acid (IAA) zeatin riboside (ZR) from average control 14 31 Abscisic (ABA), soluble sugar, starch, protein generally lower plants Combined our previous anatomical observations, these results suggested that, during development, some enzymes growth promoting hormones might be required for callus proliferation early stage vascular reconnection later stage. Nutrients provided energy whole development process. In contrast, polyphenols inhibiting seemed have negative effects on this