Comparative Study on the Endogenous Hormone Contents in Cuttings of Populus yunnanensis and P. tomentosa

Purpose Endogenous hormones contents in cortices of the cutting base of Populus yunnanensis and P. tomentosa were tested to investigate the effect of endogenous hormones on adventitious root formation of cuttings.

Methods The cuttings of easy-to-root P. yunnanensis and difficult-to-root P. tomentosa were cultured in soil. High performance liquid chromatography (HPLC) was used to examine the dynamic changes of IAA, ABA, GA₃ and ZT in cortices of the cutting base.

Results The cuttings of P. yunnanensis were 7 d for forming callus and 21 d for formatting adventitious roots, while P. tomentosa had callus in 21 d and failed rooting by 49 d. The contents of IAA and ZT in cortices of the cutting base of P. yunnanensis were higher than those in cortices of the cutting base of P. tomentosa, but the difference was not significant (P>0.05). However, the ABA and GA₃ contents in cortices of the cutting base of P. tomentosa were significantly higher than those in cortices of the cutting base of P. yunnanensis throughout the rooting process (P<0.01).

Conclusion IAA and ZT were not the main factors to affect the adventitious root formation, but the high contents of ABA and GA₃ in cortices of the cutting base could be the main inducement of cuttings of P. tomentosa failed to take adventitious roots.