Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 16, 2006
Publication Date: October 1, 2006
Citation: Viator, R.P., Johnson, R.M., Grimm, C.C., Richard Jr, E.P. 2006. Allelopathic, Autotoxic, and Hormetic Effects of Post-Harvest Sugarcane Residue. Agronomy Journal. 98:1526-1531. Interpretive Summary: With green cane harvesting, 3 to 6 tons per acre of post-harvest residue is deposited on the field surface covering the sugarcane that must reemerge for a subsequent crop. If this residue is not removed from the row top, sugar yields are reduced 5 to 15%. One possible reason for this yield loss may be the presence of toxic substances released from this leafy material as it decays. To determine the presence of possible toxicity, tomato, oat, rye, and sugarcane were grown using a mixture of water and sugarcane residue. This mixture reduced the germination of oats and rye by 17 and 14%, respectively, and seedling growth of oats and rye by 48 and 8% compared to seeds treated with pure water. Moreover, sugarcane germination was reduced by 50%, and sugarcane leaf development was delayed when using this residue and water mixture. Chemical analysis revealed the presence of benzoic acid, a known toxic substance to many crops. Agricultural equipment exists that can reposition the residue from the top of the row, where sugarcane is emerging, to the inner-row space where weeds usually grow. The presence of the benzoic acid in this space may aid in weed suppression which could reduce herbicide use. Proper residue management will ensure optimal sugarcane growth and weed control, which will both result in higher yields, increased profits, and environmental sustainability.
Technical Abstract: The allelopathic effect of sugarcane (interspecific hybrids of Saccharum spp.) post-harvest residue on oat (Avena nuda), rye (Secale cereale), tomato (Lycopersicon esculentum), and sugarcane was investigated with water soluble extracts of the residue. Oat and rye germination was reduced by 17 and 14%, respectively, and radical growth of oat and rye was reduced by 48 and 8% relative to the control (water only). The higher concentrations of residue extracts exhibited autotoxicity by reducing the germination of sugarcane by 50% and delaying early leaf development. Moreover, the lower concentration of 10% increased sugarcane bud germination by 90% compared to the control indicating hormetic effects, also. Oat, rye, and tomato effects showed poor correlation with the extract effects on sugarcane. Chemical analysis by GC/MS indicated the extract contained benzoic acid and dimethylbenzene, documented allelochemicals. Agricultural equipment exists that can reposition the sugarcane residue from the top of the row, where sugarcane is emerging, to the inner-row space where weeds usually grow. The presence of allelochemicals in this space may aid in weed suppression which could reduce herbicide use. Proper residue management could aid in optimal sugarcane growth and weed control, which will both result in higher yields, increased profits, and environmental sustainability.