From Early Toxicity to Grain Accumulation: Warming Effects on Cadmium Uptake and Translocation in Wheat (Triticum aestivum L.)
摘要
Confronted with severe global warming and soil pollution, concerns about food quality are escalating. However, research on quality risks posed by heavy metals in grains under global warming is scant, especially regarding the effect and mechanism of Cd uptake and translocation in wheat. This study conducted a series of multi-scale experiments: a 48-h wheat root elongation test, a 10-day hydroponic experiment and a 24-day soil culture experiment under various warming modes (nighttime warming and continuous warming), and a whole growth experiment under free air temperature increase (FATI), in order to better reveal the effect of warming on the uptake and translocation of Cd by wheat from different levels. One-way analysis of variance was used to test the significance of differences among different treatments. Results indicated that the temperature rise significantly heightened the sensitivity of wheat seedling roots to Cd toxicity, lowering the median effective concentration (EC50 value) of Cd on the elongation of wheat roots (from 3.1 mg kg−1 at 15 °C to 0.66 mg kg−1 at 25 °C). Warming treatments boosted wheat seedlings growth and biomass in hydroponic experiments but reduced root-shoot ratio. Both short-term hydroponic and soil culture experiments showed that warming significantly increased Cd accumulation in wheat seedlings (p < 0.05), enhancing Cd translocation factor and percentage ratio from roots to shoots, and increasing the risk of Cd accumulation in wheat grains. The FATI experiment revealed that temperature increase not only increased the Cd concentration in the aboveground parts of wheat but also significantly increased the Cd concentration in wheat grains by 22.6% to 36.5%. Warming also facilitated Cd translocation from roots to shoots and redistribution to the grains. This study underscores that warming promotes Cd uptake and translocation, providing an experimental basis for Cd exceeding risk warning under future global warming and supporting theoretical research on soil pollution and global change interactions.