The chemical interaction between plants, which is referred to as allelopathy, may result in the inhibition of plant growth and development. The objective of this research was to determine the allelopathic impact of sugarcane (Saccharum officinarum) var. 'HoCP 96-540' field residue and sugarcane bagasse extracts on the germination of three vegetable crops. Tomato (Solanum lycopersicum L.), Chinese kale (Brassica oleracea L. var. alboglabra Bailey), and cucumber (Cucumis sativus L.) seeds were treated with 4 extract concentrations (0, 16.7, 33.3, and 66.7 g/L) from either sugarcane field residue or sugarcane bagasse extracts. Germination of the tomato, Chinese kale, and cucumber seeds decreased as concentration of sugarcane field residue extracts increased. At the highest residue concentration (66.7 g/L), germination decreased by 44%, 82%, and 88% for tomato, Chinese kale, and cucumber, respectively. These results would indicate that sugarcane field residue would not be a suitable natural mulch or soil amendment for local vegetable production, especially where the vegetables were direct-seeded. If evaluated correctly, the sugarcane field residue may be an effective natural mulch for perennial ornamental plants in landscape applications, serving as a physical and chemical barrier to germinating and emerging weed species. Sugarcane bagasse extracts did not inhibit Chinese kale and cucumber germination, and only inhibited tomato germination by 13% at the greatest concentration (66.7 g/L) in 1 experiment. As the first documented bioassay implicating bagasse as allelopathic active, further research should investigate the subject using higher concentrations, and additional sugarcane and tomato varieties. Except for the one instance with tomato germination, it appears that sugarcane bagasse has potential as a natural mulch for vegetable production, although the mulch would only be a physical barrier to weed establishment and not a allelopathic chemical barrier. Future research should determine the allelopathic active compounds in sugarcane field residue and if the concentration of allelopathic chemicals vary by sugarcane variety.

Allelopathy, the chemical interaction between plants, may result in the inhibition of plant growth and development, which can include compounds released from a crop that adversely impact weed species. The objective of this research was to determine the allelopathic impact of sugarcane (Saccharum officinarum) field residue and root water extracts on seed germination of three weed species. Red morningglory (Ipomoea coccinea L.), redroot pigweed (Amaranthus retroflexus L.), and spiny amaranth (Amaranthus spinosus L.)] seeds were treated with five extract concentrations (0, 12.5, 25, 50, and 100 g/L) from either sugarcane field residue or sugarcane root extracts. The field residue and roots were from sugarcane variety 'HoCP 96-540' plant cane. Germination generally decreased with increasing sugarcane field residue extract concentrations in the three weed species tested. At the highest residue concentration (100 g/L), red morningglory, redroot pigweed, and spiny amaranth germination decreased by 29%, 17.5% and 80.5%, respectively. Germination generally decreased with increasing sugarcane root extract concentrations in red morningglory and redroot pigweed, but not with spiny amaranth. The highest root concentration (100 g/L) decreased red morningglory and redroot pigweed germination by 19.5% and 18.5%, respectively. This research provides the first bioassay demonstrating that sugarcane root extracts have allelopathic activity, and specifically in respect to red morningglory and redroot pigweed germination. Future research should investigate the allelopathic compounds present in the sugarcane field residue and roots, determine if the same allelopathic compounds are present and in similar concentrations among other sugarcane varieties, and further examine which weed species may be susceptible to the allelopathic compounds present in sugarcane roots.

Allelopathy, the chemical interaction between plants, may result in the inhibition of plant growth and development, and includes compounds released from a primary crop that adversely impact crop or weed species. The objective of this research was to observe the allelopathic impact of sugarcane (Saccharum sp.) post-harvest crop residue and mill bagasse leachate on seed germination of three other plant species. Oat (Avena sative L.) var. 'Corral', tall morningglory (Ipomoea purpurea L. Roth), and redroot pigweed (Amaranthus retroflexus L.) seeds were treated with 5 leachate concentrations (0, 12.5, 25, 50, and 100 g/L) from either sugarcane crop residue or sugarcane bagasse. Each experiment was repeated twice (Experiment 1 & 2) with each plant species, leachate concentrations, and leachate source (sugarcane crop residue and mill bagasse). The impact of leachates from sugarcane variety 'HoCP 96-540' crop residue and sugarcane bagasse differed by the species evaluated (oat, morningglory, and redroot pigweed), the leachate source (crop residue vs. bagasse), and leachate concentration (0 to 100 g/L). Oat germination was not affected leachate source or concentration. Germination for both weed species, tall morningglory and redroot pigweed, were adversely affected by leachate source and concentration. In both cases, the sugarcane crop residue leachate had a greater deleterious impact on germination than did the bagasse leachate. The response to the leachates was more consistent and severe for tall morningglory germination than redroot pigweed germination. Averaged across experiments, the 12.5 g/L crop residue concentration decreased the tall morningglory germination to 17% compared to 34% germination for the bagasse leachate, and the 100 g/L residue concentration reduce germination to 6% compared to 19% for bagasse 100 g/L bagasse concentration. The 100 g/L concentration of crop residue reduced redroot pigweed germination by 13% (Experiment 1) and 27% (Experiment 2), while the bagasse leachate reduced germination by 5% (Experiment 1) and 15% (Experiment 2). Future research should investigate the allelopathic compounds present in the sugarcane crop residue and bagasse, determine if the same allelopathic compounds are present and in the same concentration among other sugarcane varieties, and further examine which weed and crop species may be vulnerable to the allelopathic compounds present in sugarcane crop residue and bagasse.