摘要
Impacts of potassium (K) deficiency and elevated carbon dioxide (eCO2) on seed constituents have rarely been explored in most crops including soybean. A controlled environment experiment was conducted with soybean grown under a sufficient (5.0 mM) and two deficient (0.50 and 0.02 mM) levels of K fertilization at ambient (aCO2) and eCO2 (400 and 800 μmol·mol-1, respectively). Both treatments significantly affected several constituents, with the K deficiency having stronger impacts than eCO2. Out of 49 seed constituents, K deficiency and eCO2 influenced 41 and 16 constituents, respectively. The K deficiency primarily decreased on average 16 constituents including minerals (e.g., K, P, Mg, Mn, Zn, Fe, B), oil, and essential fatty acids (e.g., linoleic and linolenic acids) but enhanced 25 constituents such as protein, amino acids, simple sugars, and stress-responsive metabolites (e.g., sugar alcohols mannitol and myo-inositol and proline). An accumulation of N while decreased C concentration resulted in the lower C:N ratio in the seeds of K-deficient plants. However, protein:oil, C:K, N:P, and N:K ratios were consistently greater under K deficiency. The eCO2 also decreased minerals such as P, S, Zn, B, and essential fatty acids but enhanced the concentration of six constituents including alanine, oleic acid, fructose, and sugar alcohols across K fertilization. In addition, the impact of eCO2 on several amino acids appeared to be dependent on the severity of K deficiency. For instance, eCO2 decreased essential amino acids (e.g., valine, phenylalanine, isoleucine) in the seeds of severely K-deficient plants but not in the other treatments leading to a K × CO2 interaction. Results showed that CO2 enrichment is likely to exacerbate the decline in the concentration of seed minerals such as P, K, S, Zn and B, essential fatty acids, and amino acids under K limited conditions.
Impacts of potassium (K) deficiency and elevated carbon dioxide (eCO2) on seed constituents have rarely been explored in most crops including soybean. A controlled environment experiment was conducted with soybean grown under a sufficient (5.0 mM) and two deficient (0.50 and 0.02 mM) levels of K fertilization at ambient (aCO2) and eCO2 (400 and 800 μmol·mol-1, respectively). Both treatments significantly affected several constituents, with the K deficiency having stronger impacts than eCO2. Out of 49 seed constituents, K deficiency and eCO2 influenced 41 and 16 constituents, respectively. The K deficiency primarily decreased on average 16 constituents including minerals (e.g., K, P, Mg, Mn, Zn, Fe, B), oil, and essential fatty acids (e.g., linoleic and linolenic acids) but enhanced 25 constituents such as protein, amino acids, simple sugars, and stress-responsive metabolites (e.g., sugar alcohols mannitol and myo-inositol and proline). An accumulation of N while decreased C concentration resulted in the lower C:N ratio in the seeds of K-deficient plants. However, protein:oil, C:K, N:P, and N:K ratios were consistently greater under K deficiency. The eCO2 also decreased minerals such as P, S, Zn, B, and essential fatty acids but enhanced the concentration of six constituents including alanine, oleic acid, fructose, and sugar alcohols across K fertilization. In addition, the impact of eCO2 on several amino acids appeared to be dependent on the severity of K deficiency. For instance, eCO2 decreased essential amino acids (e.g., valine, phenylalanine, isoleucine) in the seeds of severely K-deficient plants but not in the other treatments leading to a K × CO2 interaction. Results showed that CO2 enrichment is likely to exacerbate the decline in the concentration of seed minerals such as P, K, S, Zn and B, essential fatty acids, and amino acids under K limited conditions.
