Characterization of finger millet extracts and evaluation of their nematicidal efficacy and plant growth promotion potential

Abstract

Plant-parasitic nematodes pose a significant threat to finger millet crops, poten- tially causing yield reduction of up to 70%. Extracts derived from finger millet vari- eties contain potent bioactive compounds that can mitigate nematode damage and promote plant growth. This study aimed at isolating and characterizing bioactive compounds from the finger millet varieties Ikhulule, Okhale-1, and U-15; evaluat- ing the impact of Ikhulule and U-15 extracts on the mortality of the root lesion nematode Pratylenchus vandenbergae; assessing the growth promotion effects of Ikhulule and U-15 extracts on the finger millet variety Okhale-1; and determining the efficacy of these extracts in managing plant-parasitic nematodes under green- house conditions. Extracts were obtained from both leaves and roots and tested in vitro for nematode mortality and in vivo for growth promotion and nematode control. The results showed that finger millet extracts exhibited strong nematicidal properties in vitro, achieving a mortality rate of up to 98% against P. vandenbergae nematodes. Applying these extracts to finger millet shoots significantly reduced nematode populations in both soil and roots and decreased the reproductive fac- tor to below one (1), indicating an effective nematode control. The study attributes the enhanced nematicidal effects of finger millet extracts to their bioactive com- pounds, particularly dodecanoic acid, phytol, 1,1,4a-trimethyl- 6-decahydro naph- thalene, 2,3-dihydro-benzofuran, 2-methoxy- 4-vinylphenol and ethyl ester, and hexadecanoic acid. These findings suggest that finger millet- derived extracts offer a natural solution for nematode management and broader agronomic benefits, ulti- mately contributing to overall plant health and productivity.