Effects of various warming patterns on Cd transfer in soil-rice systems under Free Air Temperature Increase (FATI) conditions

Abstract Global warming has become an important research topic in different disciplines around the world, especially in the fields of environment quality and food security. As a potential problem in soil environments, cadmium (Cd) contamination of rice under global warming conditions has not been thoroughly investigated. In this study, the fate of Cd in soil-rice systems under various warming patterns was studied via pot experiments under Free Air Temperature Increase (FATI) conditions. The patterns of warming included different temperatures (0.5 °C and 0.8 °C), different day-night durations (nighttime, daytime, and the whole day), and different warming stages (WSx) (including WS1 (seedling to tillering), WS2 (jointing to booting), WS3 (heading), WS4 (grain filling to milk ripening)). At harvest, samples of different rice tissues were collected and the Cd concentrations were measured. The results showed that warming significantly increased Cd concentrations in grain by 1.45 and 2.31 times, which was positively correlated with the two temperature increases (0.5 °C and 0.8 °C), respectively. Both daytime and nighttime warming significantly increased the Cd concentration in grain, and the daytime dominated Cd translocation from roots to shoots. In addition, warming in individual growth stages contributed to increases in Cd accumulation in grain by 31.6% (WS1), 15.0% (WS2), 20.6% (WS3), and 32.8% (WS4), respectively. Specifically, warming during the vegetative phase boosted Cd translocation from roots to shoots, while warming during maturation further increased Cd uptake and remobilization into grain. The projected results could provide a new and in-depth understanding of the fate of Cd in soil-rice systems under global warming conditions in Cd contaminated areas.