No abstract

Beggiatoa was obtained from six habitats, including four water-saturated soils from rice fields. The isolate of Beggiatoa from Bernard clay, when reinoculated into soil treatments from pure culture, significantly reduced hydrogen sulfide levels in soils and increased oxygen release from rice plants. Rice plants significantly increased Beggiatoa survival in flooded soils. Some hydrogen sulfide was necessary for survival of the Bernard clay isolate; high concentrations of hydrogen sulfide killed the Bernard clay isolate but were tolerated by a Crowley silt loam isolate from Eagle Lake, Texas. The results suggest that Beggiatoa may be an element of wetlands plant ecosystems.

No abstract

In flooded rice fields a decline in total nematode populations began shortly after the onset of soil anaerobiosis and was correlated with a sustained increase in concentration of molecular hydrogen sulfide in the soil-water phase. Laboratory tests showed that hydrogen sulfide at concentrations found in flooded fields killed 100 percent of nematodes in 5 to 10 days. The effect of hydrogen sulfide and its pattern of occurrence in the soils of water-saturated rice fields suggest that this compound can be a significant factor in the etiology and control of certain plant diseases.

No abstract