Nitrogen is a fundamental macronutrient that can be renewable. Leguminous crops applied nitrogen to the soil, thereby improving soil fertility. Nickel and cobalt are pivotal in nitrogen metabolism and biological nitrogen fixation within legumes. This investigation determined two applications of nickel and cobalt to the soil, which were applied at three different rates (0, 50, and 100 mg of nickel and cobalt kg?1 soil) with three replicates. The treatment of 0 mg of nickel with 100 mg of cobalt kg?1 soil resulted in the highest seed yield value (3.65 Mg ha?1). The treatment T5 (0 mg of nickel with 100 mg of cobalt kg?1 soil) achieved a fresh nodule weight of 304.30 kg ha?1. The greatest mean soil nitrogen concentration value was found in T6 at the flowering stage, which showed a mean value of 34.30 mg N kg?1 soil. Additionally, the best correlation was observed between nitrogen uptake in seeds and broad bean seed yield, with an R2 value of 0.88. The average concentrations of nickel and cobalt in the soil achieved values from 0.85 to 22.60 mg Ni kg?1 soil and 0.43 to 5.79 mg Co kg?1 soil, respectively, with all mean values below the acceptable toxicity thresholds. This research provides significant insight into the role of nickel and cobalt in enhancing legume nodulation to improve the yield of commercial broad bean plants.
Leaf area, seed yield, protein, PCA, nitrogen uptake, leaf cobalt concentration