Study On Allelopathic Potential And Mechanism Of Some Chinese Rice (Oryza Sativa L.) Germplasms

Allelopathy was defined as any direct or indirect harmful or beneficial effect of one plant (donor plant) on another (recipient plant) through the production of chemical compounds that released into the environment. Applying plant allelopathy to inhibit weeds can not only efficiently reduce the use of chemical herbicide and cost, but also protect environment and improve crop product.Allelopathic potential of 474 rice materials selected randomly in the rice germplasms collection of China National Rice Research Institute were evaluated by sand culture technique combined with chamber. And 11 rice varieties with allelopathic potential (RI< 0.70) were obtained by comparison of the integrated relative factor of barnyardgrass RI ( RI is greater, and allelopathic potential is smaller). After the field experiment and plant leaf water extract test, 3 rice varieties, I-Kung-Pao, No-Ikul716 and D-gu, with allelopathic potential against barnyardgrass (Echinochloa crusgalli (L.) Beauv. var. mitis (Pursh) Peterm) were obtained from 11 rice allelopathic potential materials.4 rice biological types of Zhefu802 varieties of similar genetic background and different plant morphology, IG1, IG4, IG25, IG26, were used in the experiments to study the relation between the competition and allelopathy against weeds. Results showed that rice competition ability against weeds is directly related to rice plant height and tiller angle. The data also demonstrated that rice biological types with strong competition ability to weeds also have strong allelopathic potential.Allelochemicals were analysed in I-Kung-Pao, D-gu and No-Ikul716 with allelopathic potential rice varieties, PI312777 with allelopathy and Xiushui 63 with non-allelopathy by GC-MS (Gas chromatography/ Mass spectrum) technique. The results of GC-MS analysis indicated that there were three peaks within 19-22 min. These 3 peaks are also small straight chain moleculars. Allelopathic rice and non-allelopathic rice have no significant difference in retention time and peak areas.Soluble protein, peroxidase (POD) isoenzyme and Esterase isoenzyme electrophoresis were detected in leaf and root of I-Kung-Pao, D-gu, No-Ikul716 and PI312777 with allelopathic potential and Xiushui63 with non-allelopathic rice varieties. The results indicated that isoenzyme was probable factor affecting the potential of rice allelopathy. The results will be further validated because of less detected varieties.