Effects of aqueous leaf extracts of Parthenium hysterophorus L. on growth, photosynthesis, nitrogen and phosphorus absorption, and antioxidant enzymes of wheat (Triticum aestivum)

摘要

The study was conducted under greenhouse conditions to assess the allelopathic potential of PartheniuM hysterophorus L. on wheat growth, and to discuss its physiological and biochemical mechanism. The bioassay results showed that aqueous leaf extract of Parthenium hysterophorus L inhibited the wheat germination and seedling growth, and the inhibition action increased with the increase of aqueous extract concentration, with inhibition percentages of wheat seed germination, plant height and fresh weight being 18.2%, 28.8% and 51.4% compared to the control, respectively, at aqueous extract concentration 10% (w/v). At all aqueous extract concentrations, the net photosynthetic rate and stomatal conductance were significantly inhibited, contents of chlorophyll, carotenoid, and phosphorus were reduced, and the value of Chi a:b was decreased. At the same time, the nitrogen content and nitrate reductase activity were intensively increased. However, no significant change occurring in stomatal limitation value and intercellular CO2 concentration, except at aqueous extract concentration 10%, at which both of them were obviously inhibited. Glutamine synthetase activity declined at aqueous extract concentration 2% and 4%, but increased at 8% and 10%. Meanwhile, aqueous extract significantly increased the content of malondialdehyde and inhibited catalase activity, and puperoxide dismutase and peroxidase activities were declined enormously by 56.7% and 53.2% compared to the control respectively, at aqueous extract concentration 10%. The present study showed that Parthenium hysterophorus L. leaf exhibits negative allelopathic effects on wheat.