| 要約: | Nodule endophytes and associated bacteria are non-symbiotic bacteria that colonize legume nodules. They accompany nodulating rhizobia and can form beneficial associations, as some of them are plant growth-promoting rhizobacteria (PGPR) that are able to promote germination and plant growth and increase tolerance to biotic and abiotic stress. White lupin (<i>Lupinus albus</i>) is a legume crop that is gaining relevance as a suitable alternative to soybean as a plant protein source. Eleven nodule-associated bacteria were isolated from white lupin nodules grown in a Tunisian soil. They belonged to the genera <i>Rhizobium</i>, <i>Ensifer</i>, <i>Pseudomonas</i> and <i>Bacillus</i>. Their plant growth-promoting (PGP) and enzymatic activities were tested in vitro. Strains <i>Pseudomonas</i> sp., L1 and L12, displayed most PGP activities tested, and were selected for <i>in planta</i> assays. Inoculation with strains L1 or L12 increased seed germination and had the same positive effects on all plant growth parameters as did inoculation with symbiotic <i>Bradyrhizobium canariense</i>, with no significant differences among treatments. Inoculation with efficient nitrogen-fixing rhizobia must compete with rhizobia present in the soil that sometimes nodulate efficiently but fix nitrogen poorly, leading to a low response to inoculation. In such cases, inoculation with highly effective PGPR might represent a feasible alternative to boost crop productivity.
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