Allelopathic potential of African marigold (Tagetes erecta) in sustainable tomato (Lycopersicon esculentum) production

Abstract: The present study was conducted to investigate the efficacy of African marigold (Tagetes erecta) root extract in controlling root-knot nematodes Meloidogyne incognita species and to determine its effectiveness as an intercropped plant on tomato (Lycopersicon esculentum) morphological and quality traits as well as on soil attributes. The results of the in vivo study revealed that the highest mortality rate (82.33%) of nematodes was observed in T3 treatment (3:1 marigold root extract in distilled water) after 72 hours while minimum egg hatching (9.33) by nematodes was obtained after 12 hours with a similar concentration. Whereas, the pot experiment of intercropping with tomato showed that after 45 days of transplanting, the maximum plant height (79.14 cm), number of leaves (28.22) and leaf area (24.46 cm²) in tomato were obtained in the T3 treatment (Tomato 1 + Marigold 2 + Root knot nematodes (RKN) 1). Similarly, maximum fruit TSS (4.90 °brix) and shelf life (8.67 days) were observed with the same treatment. Concerning root-knot nematode infestation, the maximum number of galls (39.33) and eggs (38.66) on the tomato root system were measured in T4 (Tomato 2 + Marigold 1 + RKN 2). However, the soil analysis of intercropped crops showed that there was no significant impact of marigold and tomato intercropping on soil pH and electrical conductivity, while this intercropping scheme slightly decreased soil nutrient levels.