Abstract

Amorphophallus konjac cannot be cultivated on the same field consecutively for extended periods, but can be cultivated on the same grove. The underlying mechanism for this is unknown and may involve the rhizosphere microbial community. Therefore, the different duration and mode for konjac were researched. Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) showed that microbial communities varied by cultivation duration and mode. Seven bacterial phyla were detected in the soil and Proteobacteria was the most abundant of these phyla. The microbial metabolic diversity following three years of continuous cultivation (sample QXFH3) was the highest, and this sample may have contained pathogenic and antagonistic microorganisms. There was almost no disease in the soil sample from grove conditions (QXN0), which was readily distinguishable from soils from field conditions (QXF0). Amino acids, carboxylic acids, and miscellaneous carbohydrates were the main carbon sources utilized by microbes in these soils. The microbial diversity index and multivariate analyses revealed that bacterial diversity increased with cultivation duration.

Key words: Discontinuous cultivation, metabolic function, microbial composition, Amorphophallus konjac.