ABSTRACT

We evaluated the use of manganese-containing amendments (Mn amendments) to improve the Mn uptake of a low-cadmium (Cd) rice cultivar, Koshihikari Kan No.1 (Oryza sativa L.), with a loss of function in the OsNramp5 that transports Mn and Cd, which was developed from an elite japonica cultivar Koshihikari. A flooded soil incubation experiment demonstrated that an increase of dissolved Mn in soils was induced by adding all 14 Mn amendments and was highly dependent on the citric acid-extractable Mn in the amendment. From the result of the incubation experiment, we selected three Mn amendments, namely, SM-1 (remarkably high Mn availability), FME-2 (high Mn availability), and SM-3 (moderate Mn availability) for a pot experiment. The pot experiment was carried out using two kinds of Mn-deficient soils with different pH (soil A and B). Manganese uptake by Koshihikari Kan No.1 was only less than one-tenth of that by Koshihikari grown on the same kinds of control soils. Dissolved Mn in soils and Mn uptake by Koshihikari Kan No.1 were substantially improved with the application of Mn amendments in the order SM-1 > FME-2 > SM-3; however, the magnitude was much more prominent in soil A than soil B. Lower soil solution pH of soil A would promote Mn dissolution from amendments and prevent dissolved Mn from adsorption on solid phase. Manganese uptake by Koshihikari Kan No.1 increased linearly with the increased dissolved Mn in the observed range (R² = 0.972, p < 0.001 for soil A and R² = 0.978, p < 0.001 for soil B). We concluded that the application of Mn amendment to Mn-deficient soils would be a promising countermeasure to ensure the healthy growth of Koshihikari Kan No.1. Additionally, soil pH control along with the application of Mn amendment would be of significance to improve the effectiveness of the application. The findings provide useful information for soil management to enhance Mn uptake by using the existing and future low-Cd cultivars with the mutant osnramp5 allele.

摘要

我们评估了使用含锰改良剂 (Mn 改良剂) 来提高低镉 (Cd) 水稻品种 Koshihikari Kan No.1 (Oryza sativa L.)的 Mn 吸收，该品种在 OsNramp5 中丧失功能运输锰和镉，这是从优良粳稻发展而来的栽培品种越光。淹没土壤孵化实验表明，通过添加所有 14 Mn 改良剂，土壤中溶解的 Mn 增加，并且高度依赖于改良剂中的柠檬酸可提取 Mn。根据孵化实验的结果，我们选择了三种锰改良剂，即 SM-1（锰含量高）、FME-2（锰含量高）和 SM-3（锰含量适中）用于盆栽试验。盆栽试验使用两种不同pH值的缺锰土壤（土壤A和B）进行。Koshihikari Kan No.1 对锰的吸收仅不到 Koshihikari 在相同类型的对照土壤上的吸收量的十分之一。通过按 SM-1 > FME-2 > SM-3 的顺序施用 Mn 改良剂，土壤中溶解的 Mn 和 Koshihikari Kan No.1 对 Mn 的吸收得到显着改善；然而，土壤 A 中的量级比土壤 B 显着得多。土壤 A 较低的土壤溶液 pH 值会促进 Mn 从改良剂中溶解并阻止溶解的 Mn 吸附在固相上。Koshihikari Kan No.1 对锰的吸收随着观察范围内溶解锰的增加而线性增加（[R ²  = 0.972，p <0.001土壤A和- [R ²  = 0.978，p <0.001土壤B）。我们得出的结论是，在缺锰土壤中应用锰改良剂将是确保越光 1 号健康生长的有希望的对策。此外，土壤 pH 值控制以及锰改良剂的应用对于提高应用的有效性具有重要意义。这些发现为土壤管理提供了有用的信息，通过使用具有突变osnramp5等位基因的现有和未来的低 Cd 栽培品种来提高 Mn 吸收。