Salicylic acid and abiotic stress influence allelochemicals and inhibitory potential of root exudates of two rice(Oryza sativa) cultivars against Barnyardgrass (Echinochloa crus-galli L.)

This study was performed to analyzing the allelochemicals by HPLC method in two rice cultivars root exudates (Tarom and Neda) under different condition. The selected cultivars were grown in hydroponic system and treated by different levels of salinity and salicylic acid treatments then the exudates were qualified by HPLC method. The inhibitory effects of exudates on barnyardgrass were also investigated. Among the studied cultivars Tarom cultivar had the highest phenolic acids, especially in combined stress and salicylic acid treatment, p-coumaric acid just detected in tarom root exudates and p- hydroxybenzoic acid and vanillic acid were detected only in some combined treatments (such as 4 dS/m, SA 1%; 8 dS/m, SA 1%; 4 dS/m, SA 2%; 8 dS/m, SA 2%). Finally it could be concluded that, in paddies when the salinity problem was observed we could recommended a blend of compounds such as salicylic acid 2% for better seedling stand and releasing of allelochemicals in mentioned condition (salt stress) against the barnyardgrass competition.