Abstract:

【Objective】 The objectives of this research were to study the effect of different concentrations of cinnamon acid application on respiratory rate and its key enzymes activity in roots of seedlings of Malus hupehensis Rehd. The mechanisms were discussed so as to provide a basis for further study on the cause of diseases in apple continuous cultivation. 【Method】 Twenty milliliters of different concentrations of cinnamon acid were added to the containers, and the respiratory rate of roots was measured by solution OXY-LAB oxygen electrodes under 25℃ and the key enzymes’ activity was also determined. 【Result】 At 5 and 25 mg•kg-1(soil), the total respiratory rate had a similar trend with tricarboxylic acid cycle (TCA) and pentose phosphate pathway(PPP) , T1, and T2 were higher than the control on the 1st day and then declined three days late but they had a recover on the last day. Embden-Meyer-hot-Parnas pathway (EMP) had a declined trend forever. The respiratory rate of the total and three pathways were decreased under 125 mg•kg-1(soil). The enzyme activity of pyrophosphate-dependent phosphofructokinase (PFK), glucose-6-phosphate dehydrogenase (G-6-PDH) and malate dehydrogenase (MDH) were similar to relative respiratory pathway. 【Conclusion】 Cinnamon acid destroyed the respiratory mechanism of roots of seedlings of Malus hupehensis Rehd., and reduced the respiratory rate of total, EMP, TCA and PPP, meanwhile, reduction of respiratory rate are increased with the improvement of concentration of cinnamon acid. Three enzymes have a similar trend with respiratory rate.

Key words: cinnamon acid, Malus hupehensis Rehd., roots, respiratory rate, enzyme activity