Avicennia marina (mangrove) soil amendment changes the fungal community in the rhizosphere and root tissue of mungbean and contributes to control of root-knot nematodes
The effect of soil amendment with Avicennia marina (mangrove) on mungbean growth and mungbean
infestation with Meloidogyne javanica was determined in greenhouse pot experiments. Galling and final nematode
population densities were reduced by all soil amendments with mangrove. To better understand whether nematode
suppression by A. marina was caused directly by the release of nematicidal factor(s) into the soil, or was due indirectly
to changes in the fungal community, the diversity of the rhizosphere populations of culturable fungi was assessed
before organic amendment (day 0), after decomposition but before seed sowing (day 15) and at harvest (day
73). Thirteen out of 20 fungal species were isolated from both A. marina-amended and unamended soils, the most
frequent genera being Alternaria, Aspergillus, Fusarium, Penicillium, Trichoderma, Mucor, Myrothecium and
Rhizoctonia. The other seven were found only in amended soils. At different times in the course of the experiment
amended and unamended soils differed significantly in the fungi isolated from the rhizosphere and/or in the concentrations
of A. marina. Trichoderma viride was isolated only from surface-sterilized mungbean roots grown in amended
soils, whereas Chaetomium sp. was isolated only from unamended soils