Allelopathic Isolation of Sugarcane Leaf Extract and Inhibitory Activity of Germination and Growth on Barnyard Grass and Slender Amaranth

Abstract

     Sugarcane leaf is a by-product after sugarcane harvesting. Previous reports indicated that the leaves content some substances inhibiting test plants. This study aimed to partially isolate allelopathic compounds of sugarcane (Saccharum officinarum L.) leaf and its inhibitory activity of germination and seedling growth against barnyard grass (Echinochloa crus-galli (L.) Beauv.) and slender amaranth (Amaranthus viridis L.). Dry leaf was extracted by the four times of 50% aqueous-ethanol giving crude yield by 1.4% w/w. The aqueous-ethanol crude (original crude: OR) was partially isolated fractions by acidbase technique giving acidic fraction (AE), neutral fraction (NE) and aqueous fraction (AQ). The fractions were assayed against germination and seedling growth of test species by petri-test method under laboratory condition. The concentrations of 1,250, 2,500, 5,000 and 10,000 ppm were investigated, and distilled water was used as control. The inhibitory activity was significance depending on fractions and concentrations. AE fraction showed the most inhibition on germination and seedling growth of slender amaranth and barnyard grass followed by NE and OR, while AQ did not display the inhibitory effect of these concentrations. The inhibitory effect increased with increasing concentration. Slender amaranth was more susceptible to the fractions than barnyard grass. These results indicated that sugarcane contained growth inhibitory substances lead for further identification of allelochemicals and development into natural herbicides for sustainable agriculture.