Effects of 3-Indole Butyric Acid (IBA) on the Physiological and Biochemical Indexes of Adventitious Root Formation in Peach Rootstock GF677

Purpose To clarify the effects of hormone induction on the formation of adventitious root of clonal rootstocks.

Methods Clear water was used as the control (CK), the bases of 1-year-old spikes of peach clonal rootstock GF677 were treated with 200, 500, 800 and 1100 mg/L 3-indole butyric acid (IBA), the physiological and biochemical indexes changes during the rooting process of its cuttings were studied.

Results The root induction effect index of 200 mg/L IBA treatment (T₁) was significantly higher than that of other treatments (P<0.05), the rooting rate reached 94.63%. The contents of total nitrogen (TP), total phosphorus (TP), and total potassium (TK) of cuttings showed a downward trend, with a decrease greater than that of CK. The activities of polyphenol oxidase (PPO), peroxidase (POD), and indoleacetic acid oxidase (IAAO), and the content of indole acetic acid (IAA) in cuttings increased first and then decreased, and the peak value appeared at the formation stage of adventitious root (21 days), with the maximum amplitude of T₁ treatment. The content of cytokinin (CTK) in the treatment groups gradually decreased, with T₁ treatment showing the largest decrease. The content of ethylene (ETH) showed a slow increase, and the T₁ treatment showed the smallest variation. Correlation analysis results showed that the rooting rate was extremely significantly negatively correlated with the contents of TN, TP, TK, and CTK (P<0.01), and extremely significantly positively correlated with IAA content, and the activities of IAAO and PPO (P<0.01).

Conclusion T₁ treatment increases the enzyme activity of cuttings significantly, and accelerates the synthesis of IAA. It indicates that the exogenous hormone 200 mg/L IBA can better regulate its oxidase and endogenous hormone levels and promote adventitious root formation.