Response of nutrient elements in leaf tissues of sweet sorghum (Sorghum bicolor) to interactive effects of soil-drenched triterpenoid phytonematicides

Abstract

Root-knot (Meloidogyne species) nematode population densities on various crops, including sweet sorghum, were consistently decreased by three triterpenoid phytonematicides that are currently available as Nemarioc-AL, Nemafric-BL and Mordica. These compounds have chemically different active ingredients. The interaction between triterpenoid phytonematicides and the accumulation of nutrients in plant leaf tissues has not yet been studied, with the exception of Nemarioc-AL and Nemafric-BL. The objective of this study was to investigate the interactive effects of triterpenoid phytonematicides on accumulation of nutrient elements in leaf tissues of sweet sorghum under microplot conditions in Limpopo Province, South Africa during 2020 and 2021. Nemarioc-AL, Nemafric-BL and Mordica were laid in a 2 × 2 × 2 factorial experiment, respectively. The test treatments were arranged in a randomized complete block design, with eight replications, conducted on artificial microplots containing steam pasteurized soil. At 150 days after inoculation, the second order interaction (Nemarioc-AL × Nemafric-BL × Mordica) significantly (P=0.05) increased accumulation of Ca, K and Mg in leaf tissues of sweet sorghum, but without affecting P, Fe, Na and Zn. Relative to untreated control, second order interaction increased Ca, K and Mg by 206, 164 and 289%, respectively. In accordance with the density-dependent growth principles of entities exposed to allelochemicals, soil-drenched administration of triterpenoid phytonematicides dramatically modified the accumulation of nutritional components in leaf tissues of sweet sorghum.