Wakelin Steven, Tillard Guyléne, van Ham Robert, Ballard Ross, Farquharson Elizabeth, Gerard Emily, Geurts Rene, Brown Matthew, Ridgway Hayley, O'Callaghan Maureen
AgResearch Ltd, Lincoln Science Centre, Christchurch, New Zealand.
Institut National Superieur des Sciences Agronomiques, Dijon, France.
PLoS One. 2018 Feb 28;13(2):e0192607. doi: 10.1371/journal.pone.0192607. eCollection 2018.
Biological nitrogen fixation through the legume-rhizobia symbiosis is important for sustainable pastoral production. In New Zealand, the most widespread and valuable symbiosis occurs between white clover (Trifolium repens L.) and Rhizobium leguminosarum bv. trifolii (Rlt). As variation in the population size (determined by most probable number assays; MPN) and effectiveness of N-fixation (symbiotic potential; SP) of Rlt in soils may affect white clover performance, the extent in variation in these properties was examined at three different spatial scales: (1) From 26 sites across New Zealand, (2) at farm-wide scale, and (3) within single fields. Overall, Rlt populations ranged from 95 to >1 x 108 per g soil, with variation similar at the three spatial scales assessed. For almost all samples, there was no relationship between rhizobia population size and ability of the population to fix N during legume symbiosis (SP). When compared with the commercial inoculant strain, the SP of soils ranged between 14 to 143% efficacy. The N-fixing ability of rhizobia populations varied more between samples collected from within a single hill country field (0.8 ha) than between 26 samples collected from diverse locations across New Zealand. Correlations between SP and calcium and aluminium content were found in all sites, except within a dairy farm field. Given the general lack of association between SP and MPN, and high spatial variability of SP at single field scale, provision of advice for treating legume seed with rhizobia based on field-average MPN counts needs to be carefully considered.
通过豆科植物 - 根瘤菌共生进行的生物固氮对于可持续牧业生产至关重要。在新西兰，最广泛且有价值的共生关系发生在白三叶（Trifolium repens L.）和豆科根瘤菌三叶变种（Rlt）之间。由于土壤中Rlt的种群大小变化（通过最可能数法测定；MPN）以及固氮有效性（共生潜力；SP）可能会影响白三叶的生长表现，因此在三个不同空间尺度上研究了这些特性的变化程度：（1）来自新西兰的26个地点，（2）农场尺度，以及（3）单个田地内。总体而言，Rlt种群数量范围为每克土壤95至>1×10⁸ 个，在所评估的三个空间尺度上变化相似。对于几乎所有样本，根瘤菌种群大小与豆科植物共生期间种群固氮能力（SP）之间没有关系。与商业接种菌株相比，土壤的SP在14%至143%的功效之间。从单个山地牧场田地（0.8公顷）内采集的样本之间，根瘤菌种群的固氮能力变化比从新西兰不同地点采集的26个样本之间的变化更大。除了一个奶牛场田地外，在所有地点都发现了SP与钙和铝含量之间的相关性。鉴于SP与MPN之间普遍缺乏关联，以及SP在单个田地尺度上的高空间变异性，基于田间平均MPN计数为豆科植物种子接种根瘤菌提供建议时需要谨慎考虑。
