No abstract

Uptake of perfluoroalkyl acids (PFAAs) by maize represents a potential source of exposure for humans, either directly or indirectly via feed for animals raised for human consumption. The aim of the following study was, therefore, to determine the accumulation potential of perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) in maize (Zea mays). Two different concentrations of PFAAs were applied as aqueous solution to the soil to attain target concentrations of 0.25 mg or 1.00 mg of PFAA per kg of soil. Maize was grown in pots, and after harvesting, PFAA concentrations were measured in the straw and kernels of maize. PFCA and PFSA concentrations of straw decreased significantly with increasing chain length. In maize kernels, only PFCAs with a chain length ≤ C8 as well as perfluorobutanesulfonic acid (PFBS) were detected. The highest soil-to-plant transfer for both straw and kernels was determined for short-chained PFCAs and PFSAs.

A conventional photometric method to determine chlorophyll concentrations in maize leaves was evaluated. It was tested whether in Mg‐deficient plant tissue the addition of MgCO3 during pigment extraction converts protoporphyrin IX into chlorophyll, falsifying concentration measurements. The non‐destructive N‐tester was used as a reference for the destructive chlorophyll determination. It is shown that both methods are valid for the determination of chlorophyll concentration in Mg‐deficient leaves.

Background Plants evolved various mechanisms to cope with metal stress. Cadmium (Cd) exposure specifically induces the synthesis of thiol‐rich substances such as phytochelatins. Due to the chemical similarity of Cd and zinc (Zn), similar detoxification mechanisms for both metals are under discussion. Aim We conducted a nutrient solution experiment to investigate thiol accumulation of parsley (Petroselinum crispum) and spinach (Spinacia oleracea) cultivars at different metal toxicity levels in vivo. Methods Three metal treatments were applied: 1 µM Zn (control), 10 µM Zn, and 1 µM Zn + 1 µM Cd. After 10 days, thiol accumulation in parsley and spinach cultivars, which differ in their Zn tissue tolerance, was measured. Results Spinach and parsley cultivars differed in metal uptake, translocation, and resistance. In spinach, Cd application induced more severe toxicity symptoms and biomass reduction than Zn. Cadmium toxicity was more pronounced in spinach than in parsley due to higher Cd translocation of spinach cultivars. Despite comparable Zn tissue concentrations, parsley did not show any Zn toxicity symptoms. Due to lower Cd tissue concentrations, only a slight browning of parsley roots was found after Cd treatment. Whereas Cd application induced thiol synthesis in both plant species, Zn excess did not. Conclusion As elevated Zn concentrations in plant tissues did not induce thiol synthesis, a contribution of phytochelatins to Zn homeostasis and detoxification was excluded.