Ph.D. Program of Agriculture Science, National Chiayi University, Chiayi City, Taiwan.
Agricultural Chemistry Division, Taiwan Agricultural Research Institute, Council of Agriculture, Executive Yuan, Taiwan.
Ecotoxicol Environ Saf. 2019 Mar;169:837-847. doi: 10.1016/j.ecoenv.2018.11.061. Epub 2018 Nov 29.
Selecting rice varieties that absorb less Cd from soil will reduce human health risks posed by Cd through rice consumption. Nine rice cultivars that are commonly grown in Taiwan were used for investigating genotypic differences in Cd tolerance and absorption. Hydroponic testing with Cd treatments of 5, 10, and 50 μM CdCl for 7-day exposure was conducted for the cultivars. The reductions in plant growth by Cd treatments were fitted to a dose-response curve; the modeling parameters, that is, the effective Cd concentration resulting in 50% reduction (EC), were obtained. The Cd concentrations in plant were expressed by a Michaelis-Menten kinetic model and the uptake rate parameters (M/k) were obtained. A field experiment was also conducted in farmland with Cd ~0.2 mg kg in soil. For the rice cultivars used in hydroponics, Cd distributions and physiological traits (CAT, HO, and MDA) in seedlings were related to their tolerances to Cd toxicity. Modeling parameters, EC and M/k, correspond to the Cd concentrations in rice plant. In the field experiment, the Cd concentrations in brown rice of the indica cultivars (i.e., TCS10, TCS17, and TNGS22) were 0.6 mg kg; these were significantly higher than those of the japonica cultivars (i.e. TY3, TK9, TNG71, KH145, TKW1, and TKW3). By contrast, the three cultivars, KH145, TKW1, and TKW3, whose Cd concentrations in brown rice were lower than 0.3 mg kg were considered safe relative to the permissible level of 0.4 mg kg. In addition, for the used cultivars, Cd concentrations in brown rice were well expressed (i.e., r = 0.95) as a function of EC, M/k, and MDA by using multiple regression. Newly bred cultivars could be screened rapidly with hydroponic testing to predict their Cd concentrations in brown rice when grown in the field.
选择从土壤中吸收较少镉的水稻品种将降低通过食用大米摄入镉对人体健康造成的风险。选用台湾地区 9 种常见种植的水稻品种，研究其对镉胁迫的基因型差异及镉吸收。采用水培法，在浓度为 5、10 和 50μM CdCl 的镉处理下进行 7 天暴露试验。用剂量-反应曲线拟合镉处理对植物生长的抑制率，得到有效镉浓度 50%（EC）的模型参数。采用米氏动力学模型拟合植株中镉浓度，得到镉吸收动力学参数（M/k）。同时在土壤镉含量为 0.2mg/kg 的农田进行田间试验。将水培试验中使用的水稻品种与幼苗中镉的分布及生理特性（CAT、HO 和 MDA）相关联，以研究其对镉毒性的耐受性。EC 和 M/k 这两个模型参数与水稻植株中的镉浓度相对应。在田间试验中，籼稻品种（TCS10、TCS17 和 TNGS22）糙米中的镉浓度为 0.6mg/kg，显著高于粳稻品种（TY3、TK9、TNG71、KH145、TKW1 和 TKW3）。相比之下，KH145、TKW1 和 TKW3 这三个籼稻品种糙米中的镉浓度低于 0.3mg/kg，与 0.4mg/kg 的限量标准相比，认为是安全的。此外，对于所使用的品种，用多元回归法，将糙米中镉浓度与 EC、M/k 和 MDA 很好地拟合（r = 0.95）。在水培试验中，可以快速筛选新育成的品种，预测其在田间种植时糙米中的镉浓度。
