Abstract
Rapeseed (Brassica napus L.) is extremely sensitive to both boron (B) and phosphorus (P) deficiencies. Application of chemical fertilizers is generally considered to be an effective agronomic practice to improve crop productivity, and it also affects soil bacterial community. However, there are few studies of the effects of balanced B and P fertilizer applications on crop yield and bacterial communities. In the present study, field experiments with five P application rates (0, 45, 90, 135 and 180 kg P2O5 ha−1) and four B application rates (0, 4.5, 9 and 18 kg Na2B4O7·5H2O ha−1) were conducted in 2016–2017 and 2017–2018 to investigate their effects on seed yield and P use efficiency (PUE) of B. napus. The smallest seed yields were obtained when B or P fertilizers were not applied (P90B0 or P0B9). Balanced B and P applications benefitted yields. The P45B4.5 treatment produced greater seed yield and PUE than the P45B18 treatment, and the P180B18 treatment produced greater seed yield and PUE than the P180B4.5 treatment. Sequencing of 16S rRNA genes revealed that the P90B9 treatment had greater soil bacterial diversity, and a different bacterial community composition, compared with the P90B0 or P0B9 treatments. Overall, our results underline the importance of balanced B and P nutrition for maximal seed yield of B. napus and the effects of B and P fertilizers on the soil bacterial community of B. napus.
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•Balanced application of B and P fertilizers increases soil bacterial diversity.•Appropriate B and P combination has a positive synergistic effect on PUE and seed yield of rapeseed.•The positive synergistic effects differ among rapeseed cultivars.•About 1 Na2B4O7·5H2O: 10 P2O5 in the field experiments reported here improves seed yield of rapeseed.