Responses Of Phenolic Compounds In Poplar Leaves To The Temperature Strikingly Dropped In Autumn

The experiment used three poplar varieties(P,psuedo-simonii×P.nigra×P.nigra C L.'A5', P.psuedo-simonii×P.nigra×P.nigra C L.'HeilinⅢ',P.deltoides×P.cathangana) with different frozen resistance as tesing materials.The membrane permeability,phenols content, polyphenoloxidase activity and soluble sugar content response to the temperature strikingly dropped in different frozen resistance poplar leaves which treated with low temperature when poplar won't enter into dormancy phase in autumn.The results was showed:The membrane permeability of three poplar varieties leaves raised with temperature down. The membrane permeability has no significant change with slight treatment of temperature strikingly dropped,but come with stronger treatment of temperature strikingly dropped, membrane permeability has significant changed.P.deltoides×P.cathangana has most significant changed,P.psuedo-simonii×P.nigra×P.nigra C L.'A5' has a little changed.This show that membrane of P.psuedo-simonii×p.nigra×p.nigra C L.'A5' leaves has the highest resistance to chilling injury,then P.psuedo-simonii×p.nigra×p.nigra C L.'HeilinⅢ' and P. deltoides×P.cathangana.After treatment of temperature strikingly dropped,there is no significant change in in total phenol,lignin,flavonoid in leaves of three poplar varieties,but our research also find that the content of total phenol and lignin in P.deltoides×P.cathangana leaves is low.the content of condensed tannin in leaves changes with different frozen resistance of poplar varieties. condensed tannin content in leaves of P.deltoides×P.cathangana is lower then in P.psuedo-simonii×P.nigra×P.nigra C L.'A5' and P.psuedo-simonii×P.nigra×P.nigra C L.'HeilinⅢ',and the content of condensed tannin in P.deltoides×P.cathangana leaves has no significant change all long.As the temperature was low outside,polyphenoloxidase activity in P.psuedo-simonii×P. nigra×P.nigra C L.'A5' and P.psuedo-simonii×P.nigra×P.nigra C L.'HeilinⅢ' leaves raised remarkably with enhancing the degree of temperature strikingly dropped,polyphenoloxidase activity in P.deltoides×P.cathangana always has no significant change,but the activity of polyphenoloxidase in P.deltoides×P.cathangana leaves is higher than in P.psuedo-simonii×P. nigra×P.nigra C L.'A5' and P.psuedo-simonii×P.nigra×P.nigra C L.'HeilinⅢ' leaves.The soluble sugar content in three poplar varieties leaves raised with temperature down. In two days when temperature dropped naturally,P.psuedo-simonii×P.nigra×P.nigra C L.'A5' leaves has highest soluble sugar content,and P.deltoides×P.cathangana leaves has lowest.