Study Of Reed Aqueous’s Allelopathy On Alligator Weed(Alternanthera Philoxeroides)

As an exotic invasive plants, alligator weed, Alternanthera philoxeroides (Martius) Grisebach, has caused serious ecological damage, economic losses and social impact, which lead to that the weed become the world’s evil nature grass. It is urgent to find an eco-safe, cost-effective measures to control its invasion. The purpose of this study is to invent a comprehensive technology to control and utilization alligator weed. Based on the status research of alligator weed in Shandong Province Nansihu basin, the method and mechanism of reed alternative control were researched. This research will guide the control of alligator weed in Nansi Lake basin, Shandong Province, even northern China.The conclusions were drawn as follows:(一)Aqueous extract of Reed inhibited the germination of Alligator Weed.Allelopathy of Reed on Alligator Weed mainly expressed for decreasing the germination rate and growing speed, delaying the germination and reducing the germination number. At10%concentration, allelopathy was less obvious than20%and50%concentration in both water planting and pot culture experiments. In water planting experiments, germination rate decreased26.7%and86.7%respectively, germination number decreased57.1%and71.4%respectively; In pot culture experiments planting experiments, germination rate decreased26.7%and60.0%respectively, germination number decreased29.8%and59.8%respectively; Aqueous extract of Reed had allelopathy on growing speed of new shoot.(二)The extract of reed had a strong inhibitory effect on the growth of Alligator Weed in hydroponics habitat:√Allelopathy of Reed on biomass of Alligator Weed expressed for inhibition of fresh weight, root shoot ratio and winding number.also the promotion of height; √Allelopathy of Reed on photosynthesis of Alligator Weed expressed for affecting photosynthetic pigment and its changing trend. Experimental result showed that effect on chlorophyll a was stronger than chlorophyll b and carotenes;√The extract of reed affected the catalase (CAT) content of Alligator Weed. CAT activity was significant (p<0.05) under different of concentration of reed extract and stress time. Inhibition effect on CAT activity had a trend of strengthen with the increasing of concentration of reed extract and stress time.At50%concentration, CAT activity decreased sharply on the30d、40d、50d, more than25%.√The extract of reed increased themembrane lipid peroxidation and the membrane passage of Alligator Weed, which leaded to the decreasing of selective permeability and electrolyte spillover. All above speedup ageing and affected the water and ion absorption of Alligator Weed.Results showed malonaldehyde (MDA) content of Alligator Weed was significant (p<0.05) under different of concentration of reed extract and stress time.√The extract of reed affected the growth of Alligator Weed by affecting other physiological and biochemical mechanism. The growth and development status of the root is reflected in the root activity which is the overall indicator of the root vitality.The extract of reed had a strong inhibitory effect on the root activity of Alligator weed and significantly (p<0.01)difference under the different concentration of treatment. Nitrogen and phosphorus content increased with the increasing of the concentration of treatment.(三)The extract of reed had a definite inhibitory effect on the growth of Alligator Weed in native habitat, which is similar to the regular pattern in hydroponics habitat. For instance inhibitory on(四)The inhibitory effect was weaker than it in hydroponics habitat. Allelopathy on Alligator Weed in native habitat showed both promotion and inhibition, but inhibition only in hydroponics habitat.