Cobalt and molybdenum stimulate compounds of primary metabolism, nitrogen forms, and photosynthetic pigments in peanut plants (Arachis hypogaea L.)

The objective of this study was to evaluate the effects of cobalt (Co) and molybdenum (Mo) doses in the treatment of seeds on the biosynthesis of nitrogen compounds, photosynthetic pigments, sugars, and production of peanut plants. The doses of Co and Mo used were 0, 2, 3, and 4 mL kg⁻¹ seed, which were applied immediately before sowing. Seeds treated with Co and Mo at a dose of 4 mL kg⁻¹ yielded peanut plants with higher concentrations of photosynthetic pigments, carotenoids, and sucrose in leaves. Application of Co and Mo doses also increased biological nitrogen fixation by increasing the concentration of allantoic acid, nitrate, ammonia, and amino acids in leaves. The concentration of total amino acids corresponded to most of the nitrogen compounds (on average 50%), followed by the concentrations of nitrate (35%), ammonia (11%), allantoic acid (7%), and allantoin (0.2%). Application of 4 mL kg⁻¹ increased the production of total amino acids compared with the control treatment. Pod yield was not affected by the Co and Mo doses; however, treatment of peanut seeds with 4 mL kg⁻¹ was the most viable alternative for increased production of primary metabolism compounds, nitrogen forms, and photosynthetic pigments in peanut plants. This study provides important information regarding the role of Co and Mo in the biological nitrogen fixation of peanut plants. Future experiments should be conducted using a dose of 4 mL kg⁻¹ with different genotypes to verify the potential for increasing peanut yield.