Research Of Allelopathy And Its Mechanism On Aqueous Extracs From Hot Pepper

Hot pepper(Capsicum frutescens L.) is an important solanaceae crop species, which is cultivated widely around the world. However, it can cause serious problems including poor plant growth, declining production and quality when it is cultivated consecutively for years on the same land. Allelopathy may be one of the reasons for continuous cropping obstacle of hot pepper. Now, it is a key project to overcome its disadvantageous effects. By means of bioassay in laboratory, the allelopathy of hot pepper aqueous extracts on seed germination and seeding growth of six vegetables was studied in this paper, in which the sensitivity of cucumber and cowpea to hot pepper aqueous extracts was determined. Then the allelopathic mechanism of hot pepper was discussed by the measured of soil enzyme activity, protective enzyme activity and chlorophyll fluorescence parameter in cucumber and cowpea. The main results were presented as follows:1.The allelopathy of hot pepper was changed with the difference of receivers plant.The resulted showed that the sequence of hot pepper aqueous extracts was cucumber> tomato> cabbage> chinese cabbage> lettuce> cowpea. Which suggested that cowpea can be the optimization crop in the hot pepper rotation, while avoided to cucumber.2.The allelopathy of hot pepper was different with the difference of hot pepper aqueous part. The allelopathic effect order of different part aqueous extracts was leaf>root>stem. Because of the deeply allelopathy in leaf, it was suggested that the residue of leaf was cleaned timely to reduce the allelopathy effect on the next crop.3.The allelopathy of hot pepper was different with the hot pepper aqueous extracts concentration. In present study,the allelopathy of hot pepper aqueous extracts showed double effects, promoted at low concentration and inhibited at high concentration. In the concentration of0.01g/mL and0.02g/mL, the receivers were stimulated by the aqueous extracts from root and steam, while it were inhibited in the concentration of0.03g/mL and0.04g/mL. In the concentration of0.01g/mL, the receivers were stimulated by the aqueous extracts from leaf, while was inhibited in the other concentration. 4. With the changing of root environment, the increasing of protective enzyme activity and the decreasing of photosynthesis, the research results of allelopathy mechanism showed that the receiver crops were effected by the hot pepper aqueous extracts. With the increasing of aqueous extracts concentration, the regular of each physiological index was presented, in which the urease activity was increased; the sucrase activity, the catalase activity and root activitiy were increased at the beginning, while decreased later; the activities of SOD,POD, the content of MDA and the Fo in receptor vegetable were increased, while the Fv/Fm、ΦPSⅡ-、qP、ETR、chlorophyll was decreased, finally impaired the process of PS Ⅱ.