关键词: 水培, 水稻, 镉铅铜复合污染, 转移率, 镉低积累突变体

Abstract: As heavy metal pollution in nature is dominated by multiple heavy metal pollution, the current study investigated the Cd uptake, transport and grain accumulation of a low-Cd-accumulation rice mutant (T2-1), based on field and hydroponics experiments. The results showed that Cd accumulation was significantly lower in T2-1 than in the wild type 9311. Compared with 9311, Cd accumulation in T2-1 with a single Cd-contaminated field was significantly reduced by 29.72%-61.63%. However, the content of Cd in grains of T2-1 planted on the plots contaminated by multiple heavy metals was reduced by only 11.07%. The results indicated that other heavy metals affected the absorption and transfer of Cd by T2-1 under the conditions of multiple heavy metal pollution. Under hydroponic conditions, seedling height and dry weight decreased with the addition of Pb and Cu. Compared with Cd and Cd-Pb treatments, addition of Cu had more significant effects on inhibiting rice growth. The trend of seedling height and dry weight were the same at 15 and 30 d. Dry matter accumulation of T2-1 was slightly smaller than 9311, which might be related to the energy consumption of fixing more Cd in roots of T2-1. The accumulation of Cd in root of T2-1 was greater than that of 9311, while that Cd transfer from root to shoot was lower in T2-1 than in 9311. Low concentration of Pb significantly promoted Cd uptake by rice seedlings, indicating that low concentration of Pb enhance Cd bioavailability in rice. In the Cd-Cu and Cd-Pb-Cu treatments, the contents of Cd in shoots and roots of two rice seedlings decreased significantly compared with those under Cd stress alone. Cu can inhibit the transfer of Cd in T2-1, and the inhibitory effect is much greater than the promotion effect of Pb. Overall, application of low-Cd-accumulation rice mutant has a promising option to alleviate Cd pollution in rice production and enhance food security. Whereas, as multiple heavy metal pollution affects the absorption, transportation and accumulation of Cd in rice，the identification of multiple heavy metal pollution should be considered in the screening of low-Cd-accumulation cultivars.

Key words: hydroponics, rice, Cd-Pb-Cu interaction, transfer rate, low-Cd-accumulation mutant