Effects of chlorsulfuron and cadmium on metabolites of maize seedlings

The impact of persisting herbicide residues on succeeding crops is of great concern to farmers because even the presence of very low concentrations can inhibit growth of crop and cause crop reduction. Furthermore, wastewater irrigation can lead to cadmium accumulation in soils. Thus, the co-occurrence of low amounts of herbicide residues and cadmium within agricultural fields are difficult to avoid. How the combination of these two pollutants affect plant metabolites remains to be elucidated and thus warrants investigation. Maize seeds were planted in soil that had been sprayed with chlorsulfuron and Cd, then we studied the effects of exposure to the herbicide chlorsulfuron (0.001, 0.003, 0.005, 0.008, and 0.010 mg kg^-1) and cadmium (as 5.0 mg kg^-1 CdCl₂) on maize seedlings by utilizing nuclear magnetic resonance (NMR) after 21 d. Principle component analysis of¹H NMR spectra clearly discriminated between control and treatment groups. Compared with chlorsulfuron-only treatments, treatments using both contaminants showed higher content of phenolic acids, aspartic acid, choline, β-galactose, and α-glucose in the seedlings. Contrary to previous reports, we found larger pools of branched-chain amino acids in seedlings exposed to chlorsulfuron and CdCl₂. These findings indicate that CdCl₂ did not aggravate the effects of chlorsulfuron on maize seedlings metabolites. CdCl₂ elicited significant changes in plant metabolism at a concentration that did not impair plant growth. Moreover, chlorsulfuron did not inhibit branched chain amino acid synthesis.