Abstract

Both root-knot nematode and sugarcane aphid are economic pests of sweet stem sorghum. In most cases, these pests are economically managed through plant resistance. Nematode resistant sweet stem sorghum cv. ‘Ndendane-X1’ is highly sensitive to sugarcane aphid, with limited information on how it would perform under aphid infestations. This study was conducted during 2018 at Green Biotechnologies Research Centre of Excellence, University of Limpopo, South Africa with an objective to investigate the effects of sugarcane aphid on sucrose in sweet stem sorghum and its resistance to Meloidogyne species. Three separate trials, each for M. incognita race 2 (Trial 1), M. incognita race 4 (Trial 2) and M. javanica (Trial 3), were initiated under microplot conditions, using 2 × 2 factorial experiment arranged in randomised complete block design (RCBD). At 150 days after planting, in Experiment 1, 2 and 3, nematode × aphid interaction significantly reduced sucrose from 17 to 74%, increased nematode reproductive potential from 152 to 320%, reduced plant growth from 20 to 48% and nutrient elements in leaf tissues from 40 to 52%, respectively. In conclusion, the sugarcane aphid broke resistance to Meloidogyne species in sweet stem sorghum cv. ‘Ndendane-X1’ and therefore, aphid population densities should be managed if growers have to benefit from the nematode resistance of the test cultivar.