Evaluation of screening methods to determine the allelopathic potential of rice varieties against Echinochloa crus-galli Beauv. var. oryzicola ohwi

摘要

This study was conducted to compare four methods (Relay seeding, ratooning, straw meal mixture and hydroponic culture) to identify a simple, rapid and reliable technique for mass screening of rice varieties for allelopathy potential to barnyardgrass (Echinochloa cnis-galli Beauv. var. oryzicola Ohwi). The relay seeding method, revealed differences in barnyardgrass growth inhibition between rice varieties. The hydroponic culture screening method, showed differences in barnyardgrass root length, growth and pH of the culture solution.. The ratoon screening method, showed variability in rice varieties potential for growth inhibition of barnyardgrass. Rice varieties showing high growth inhibition of barnyardgrass were taller, had higher tillers and produced more biomass than did the low inhibition varieties. The rice straw meal and soil Mixture cultivation method also showed the maximum coefficient of variation in barnyardgrass root length. The growth parameters (early vigour, plant height, tillers number) of 39 rice varieties from 2 groups (Japonica and Indica varieties) were compared for suppression effect on root length of barnyardgrass (Echinochloa crusgalli var. oryzicola.). Amongst the 39 rice varieties tested Taichung native I exhibited the highest allelopathic potential. The laboratory screening of rice varieties showed. different growth ability at different growth density and growth stage of rice in the cultivation of soil condition.