Effects of Three Plant Extracts on Growth and Development of Dodder and Soybean and on Protective Enzymes of Host

The ethanol extracts of Melia azedarach bark and leaves, Eucalyptus robusta , leaves, Sapium sebiferum leaves were studied which treated to dodder and its host soybean seedlings in different concentrations, the impact of three plants extracts on dodder and soybean seedlings were evaluated at the 15 days after spraying. The results showed that three extracts in low concentrations had no significant influence on the growth and development of dodder and soybean seedling. In high concentrations (0.25 g/mL), Eucalyptus robusta leaves extract caused damage to soybean seedling and dodder reached at 64% and 70% respectively, while the damage of Melia azedarach bark extract was 78% to dodder and only 7% to soybean seedlings. On the other hand, the treatment of Eucalyptus robusta leaves and Melia azedarach bark extract led to superoxide dismutase (SOD) activity of soybean's leaves rising, the highest values were 2.37 times and 2.0 times respectively as much as the control groups. But the effects in activities of peroxidase (POD) and catalase (CAT) were different, which the highest value of POD activity caused by Eucalyptus robusta leaves extract was 2.28 times compared to the control group. Whereas CAT activity rose highest under Melia azedarach bark extract treatment, the maximum was 1.58 times than the control group, which suggested the damage to soybean caused by Eucalyptus robusta leaves extract was associated with its lower activity in CAT.