Cutting height of main crop has profound effects on cadmium but not arsenic concentration of ratoon crop in rice

Rice contamination with heavy metals seriously threatens human health. Ratoon rice plays a vital role in food security in China, whereas limited information is available on its heavy metal accumulation. Cutting height of main crop is an important crop management practice affecting the growth and yield of ratoon crop (RC), whereas its effects on heavy metals accumulation in RC is still unknown. Field experiments were conducted in 2019 and 2020 to investigate the effects of different cutting heights (high: 45 cm, medium: 15 or 25 cm, and low: 5 cm) on cadmium (Cd) and arsenic (As) concentrations in RC. Cutting height had small and inconsistent effects on As concentration in RC. However, grain Cd concentration of RC in high and medium cutting heights were significantly reduced by 87.5 % and 79.8 % than that in low cutting height, respectively. Similarly, Cd concentrations of stubble and straw at maturity were also significantly lower in high and medium cutting heights than in low cutting height. Regenerated tillers in the low node position were responsible for the differences in Cd concentration among the cutting heights. The increase in cutting height of main crop significantly decreased Cd concentration but has small effects on As concentration in RC. Our results suggest that high cutting height during the harvest of main crop should be considered when rice ratooning is practiced in the environment with Cd-contaminated soil.