The Allelophatic Effects of Acacia mangium leaves on the Seed Germination and Initial Growth of Maize (Zea mays L.) and Rice (Oryza saliva)

Laboratory and greenhouse experiments were conducted to study the allelophatic effects of Acacia mangium on the germination and initial growth of two cash crops, maize (Zea mays) and rice (Oryza sativa). The germination, relative growth rates and the biomass allocation of maize and rice were determined using fresh and litter A. mangium leaves that were grinded and soaked for 24hrs; the filtrates were then diluted into 5 concentrations, 10%, 25%, 50%, 75% and 100%. Based on the results obtained from the present study, the A. mangium leaves extract exhibit allelophatic potential on rice, as indicated by the low seed germination and the initial growth to a certain extent but no effects was observed in maize. In term of relative growth rates (RGR) of elongation length of the seedlings, the concentration of the extract has an insignificant effect while it is more affected by the type of materials used which are control (distilled/tap water), fresh and dry A.mangium leaf extract. Overall, the growth of the seedlings were not affected negatively by the A.mangium leaf extract although the germination percentage in rice had a significant negative effect. Further studies are necessary to determine the exact chemical constituents of A.mangium accounting for its allelopathic activity. Besides that, it is suggested that a higher concentration of A. mangium leaf extract is used for future study.