Assessing the efficacy of metal nutrient supplementation for faba bean (Vicia faba L) with the coinoculant Pantoea agglomerans DUS1-2Report

Faba bean (Vicia faba L.) is a valuable crop adapted for climate change. It contributes to cropping system sustainability by providing protein-rich food, biologically fixing atmospheric nitrogen and diversifying production systems. Because the average yield of V. faba in Australia is only 1.3 tonnes per hectare, enhancing V. faba tolerance to abiotic stressors is critical to increasing yield inthe region. Furthermore, V. faba forms a symbiotic relationship with Rhizobium leguminosarum bv. viciae WSM1455, a plant growth-promoting bacterium (PGPB) that produces root nodules where nitrogen fixation occurs. This research aimed to investigate novel applications for mitigating nutrient uptake and enhancing the growth of V. faba under low nutrient conditions by utilising (PGPB) Pantoea agglomerans DUS1-2. V. faba, was treated with four different concentrations of copper, manganese, and zinc, ranging from 100 ? 800 ?M. The different concentrations had no significant influence on the yield production of V. faba. Furthermore, the varying concentrations of metals copper, manganese, and zinc, ranging from 100 ? 800 ?M, did not affect R. leguminosarum and P. agglomerans CFU growth. Therefore, the plants were further treated with 800 ?M of copper, manganese and zinc with inoculation and co-inoculation of R. leguminosarum and P. agglomerans. The results of this study revealed a significant (p<0.05) increases in V. faba dried biomass when inoculated with P. agglomerans and treated with manganese by 231 mg for shoots and when treated with zinc by 112 mg for shoots and 81 mg for roots. These improvements in growth were most likely caused by P. agglomerans ability to solubilize manganese and zinc, providing it with a competitive advantage and allowing the isolate to exert PGP effects on the plants. This study reveals that P. agglomerans may only have PGP effects on V. faba when supplemented with manganese and zinc in low nutrition soils.