Abstract Microbial inoculants are gaining prominence in technologically advanced agri-systems due to the need for alternatives to the most pollutant agricultural inputs. The objective of this work was to improve the agronomic performance of the rhizobial inoculants for common bean, based on the superior native strain Rlp-LCS0306 of Rhizobium leguminosarum bv. phaseoli (R), through co-inoculation with non-rhizobial partners, namely the autochthonous isolate RVPB2-2 from Pseudomonas brassicacearum subsp. neoaurantiaca (P) and the type strain of Azotobacter chroococcum. It has been reported that co-inoculation improves nodulation, nodule functions and plant growth, although there is a lack of field testing in technologically advanced agri-systems. This work bridges this gap. In the field trial which was carried out in two different environments, the consortium R + P was the most successful, because it increased the N2 fixation by 51.7 kg ha−1 (87 %) and the yield by 1337 kg ha−1 (59 %), compared with the uninoculated and unfertilised control. In addition, the increased yield observed following inoculation with the above indicated consortium was 16.7 %, compared with the single rhizobia inoculation, and this increase was also superior to that observed with other consortia. The superiority of the R + P consortium could partially be explained because in this study, there was an increased tendency for improved nodule biomass and function following co-inoculation. While this increase was not deemed to be statistically significant, it is noteworthy that nodule biomass increased by 25 % in average and N-fixed by more than 20 %, which, in turn, could be explained by the indole-3-acetic acid (IAA) production and 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity of the P strain. However, further delineation of the system is required in order to explain the yield improvement exerted by the consortium. Here, we observed, i) the strong plant growth-promoting potential displayed by the P strain; ii) the colonisation of the nodules by the P strain; and iii) the strategy of colonisation of complementary spaces inside the nodules by P (intercellular) and the rhizobia (intracellular), by confocal microscopy.

中文翻译：

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普通豆对与根瘤菌和假单胞菌内生菌共接种的产量反应和根瘤内不同定植空间的微观证据

摘要 由于需要替代污染最严重的农业投入物，微生物接种剂在技术先进的农业系统中越来越突出。这项工作的目的是改善普通豆类根瘤菌接种剂的农艺性能，基于豆科根瘤菌 bv 的优良天然菌株 Rlp-LCS0306。菜豆 (R)，通过与非根瘤菌伙伴共同接种，即来自芸苔假单胞菌亚种的本土分离物 RVPB2-2。neoaurantiaca (P) 和色球菌固氮菌的典型菌株。据报道，虽然在技术先进的农业系统中缺乏现场测试，但联合接种可改善根瘤、根瘤功能和植物生长。这项工作弥合了这一差距。在两种不同环境下进行的现场试验中，联盟 R + P 是最成功的，因为与未接种和未施肥的对照相比，它增加了 51.7 kg ha-1 (87%) 的 N2 固定和 1337 kg ha-1 (59%) 的产量。此外，与单一根瘤菌接种相比，接种上述菌群后观察到的产量增加了 16.7%，而且这种增加也优于使用其他菌群观察到的增加。可以部分解释 R + P 联合体的优越性，因为在本研究中，共接种后结核生物量和功能的改善趋势增加。虽然这种增加在统计上并不显着，但值得注意的是，结核生物量平均增加了 25%，固氮增加了 20% 以上，反过来，可以通过 P 菌株的吲哚-3-乙酸 (IAA) 产生和 1-氨基环丙烷-1-羧酸酯 (ACC) 脱氨酶活性来解释。然而，需要进一步描述该系统，以解释联合体实现的产量提高。在这里，我们观察到，i) P 菌株显示出强大的植物生长促进潜力；ii) P 菌株对结核菌的定植；iii) 通过共聚焦显微镜观察 P（细胞间）和根瘤菌（细胞内）在根瘤内的互补空间定植的策略。i) P 菌株显示出强大的植物生长促进潜力；ii) P 菌株对结核菌的定植；iii) 通过共聚焦显微镜观察 P（细胞间）和根瘤菌（细胞内）在根瘤内的互补空间定植的策略。i) P 菌株显示出强大的植物生长促进潜力；ii) P 菌株对结核菌的定植；iii) 通过共聚焦显微镜观察 P（细胞间）和根瘤菌（细胞内）在根瘤内的互补空间定植的策略。