Rhizosphere soil method for evaluating the Allelopathic potentiality of the Soils of paddy weeds around the root

摘要

The allelopathic impact of soil collected the beneath root zone of paddy weeds viz. Cyperus difformis, Echinochloa crusgalli, Paspalum paspaloides and Sagittaria trifolia on paddy seeds like Tarom, Neda and Fajer varieties were investigated under laboratory condition in 2009. To prove the allelopathic effect of root zone soil of above weeds, the soil was analyzed to obtain the values of pH, EC, Total Nitrogen, Phosphorus, Potassium, Zinc, Copper, Manganese and Iron. The results showed that radicle length of Tarom variety were significantly affected when were allowed to growth in soil collected beneath the root zone of Cyprus difformis over control with confidence level 95 % only. Germination of above variety was significantly hampered by collected root zone soil of all selected weeds except Paspalum paspaloides. The major phytotoxicity was caused by Echinochloa crusgalli over control. The rhizosphere soil of Echinochloa crusgalli significantly diminished radicle length of Neda variety only. The soil collected beneath the roots of selected weeds suppressed hypocotyl length of above test crop while had a weak effect on percentage of germination. In case of Fajer variety, radicle length of paddy seedling was significantly hampered by all the selectedweeds. Collected root zone soil of Echinochloa crusgalli proved more inhibitory effect on radicle length of test crop. Hypocotyl length of above test crop was significantly decreased due to all studied weeds while root zone soil of Echinochloa crusgallihad significant inhibitory effect on germination percentage of above test crop only. Root zone soil analysis proved that soil collected beneath the roots of Echinochloa crusgalli had less quantity of Total Nitrogen, Organic Matter, Phosphorus over otherweeds and control soil. It indicates that growth of studied weed particularly Echinochloa cms galli changed soil chemistry and reduced soil nutrient content. In general, seedling growth of Fajer variety was more sensitive to allelopathic inhibition of studied weeds over Neda and Tarom varieties.