Over the last three decades, farming systems in Europe and Australia have seen a decline in legume plantings, leading to reduced soil carbon and fertility, and an increase in plant disease, reliance on industrial nitrogen fertilizer and herbicides. In Australia, one reason for this decline has been the movement towards sowing crops and forages into dry soil, before the opening rains, as a consequence of climate variability. This practice predicates against the survival of rhizobial inoculants, and hence generates uncertainty about legume performance. The research reported here was initiated to improve the robustness of a specific forage legume/rhizobia symbiosis to increase nitrogen fixation in low pH, infertile soils. Rhizobial strains (Rhizobium leguminosarum biovar viciae) from Pisum sativum L. were sourced from acid soils in southern Italy and southern Australia. Strains were evaluated for N fixation on the forage legumes P. sativum, Vicia sativa and Vicia villosa, then for survival and persistence in acid soils (pH_Ca 4.6). Fourteen of the strains produced a higher percentage of nitrogen derived from the atmosphere (%Ndfa) compared to commercial comparator strain SU303 (<78%). Twenty‐two strains survived sufficiently into the second season to form more nodules than SU303, which only achieved 3% of plants nodulated. Elite strains WSM4643 and WSM4645 produced six times more nodulated plants than SU303 and had significantly higher saprophytic competence in acid soil. These strains have the ability to optimize symbiotic associations with field peas and vetch in soils with low fertility, carbon and pH that are restrictive to the current commercial strain SU303.

中文翻译：

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从地中海起源中心采购豆科根瘤菌biovar viciae菌株，以优化酸性土壤上生长的饲用豆类的固氮能力

在过去的三十年中，欧洲和澳大利亚的耕作制度减少了豆类作物的种植，导致土壤碳和肥力降低，植物病害增加，对工业氮肥和除草剂的依赖。在澳大利亚，这种下降的原因之一是由于气候多变性，在降雨开始之前，已将作物和草料播种到干燥的土壤中。这种做法不利于根瘤菌接种物的生存，因此对豆类表现产生不确定性。此处报道的研究旨在提高特定草料豆科植物/根瘤菌共生的健壮性，以提高低pH值，不肥沃土壤中的固氮能力。根瘤菌（根瘤菌生物变种蚜）从豌豆（Pisum sativum L.）来自意大利南部和澳大利亚南部的酸性土壤。评估菌株对饲用豆科植物P的固氮作用。豌豆，野豌豆和野豌豆，然后在酸性土壤（pH _Ca4.6）。与商用比较器菌株SU303（<78％）相比，其中14种菌株从大气中产生了更高百分比的氮（％Ndfa）。22个品系到第二季已足够存活，形成了比SU303多的结节，SU303仅结瘤植物的3％。优良菌株WSM4643和WSM4645的结瘤植物产量是SU303的六倍，并且在酸性土壤中的腐生能力明显更高。这些菌株具有优化与豌豆共生关系的能力，并在低肥力，低碳和低pH的土壤中限制了紫罗兰的生长，这限制了目前的商业菌株SU303。