Effect of fungicides on association of arbuscular mycorrhiza fungus Rhizophagus fasciculatus and growth of Proso millet (Panicum miliaceum L.)

The detrimental effects of fungicides on non-target beneficial microorganisms such as arbuscular mycorrhizal (AM) fungi are of interest to agriculture. Rhizophagus fasciculatus was found to be predominant (21%) AM fungus in studied soil compared to other species (2-9%). Hence, we have conducted a study to evaluate the potential effects of fungicides Benomyl(Methyl [1-[(butylamino) carbonyl]-1H-benzimidazol-2-yl] carbamate), Bavistin (methyl benzimidazol-2-ylcarbamate), Captan ((3aR, 7aS)-2-[(trichloromethyl) sulfanyl]-3a,4,7,7a-tetra hydro-1H-isoindole-1,3(2H)-dione and Mancozeb (manganese ethylene-bis(dithiocarbamate) (polymeric) complex with zinc salt) on association of R. fasciculatus with Proso millet (Panicum miliaceum L.), an emerging drought-resistant crop that represent a cheap source of nutrients for human in developing country. The results of this study showed significant (P <= 0.05) higher AM colonization (69.7%), spore density (193 spores), plant growth (both lengths and weights of shoots and roots) and grain yield (154 grains per panicle) in mycorrhizal Proso millet plants treated with Captan compared to other fungicides and untreated controls. In contrast, Benomyl had adverse effect in all parameters measured (45.3% AM colonization, 123 spores, 105 grains per panicle, etc.). Our results also showed that AM colonization significantly improve growth and grain yield of Proso millet plants compared with non-mycorrhizal plants. Therefore, the present study demonstrated that Proso millet crops could be improved with native AM fungal inoculation, however, the type of fungicide applied in soil and its effect on plant performance must be seriously considered.