College of Biological Science and Engineering, Jiangxi Agricultural University, Nanchang 330045, China; Key Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
College of Resources and Environmental Sciences, Hunan Normal University, Changsha 410081, China.
Sci Total Environ. 2021 May 20;770:145302. doi: 10.1016/j.scitotenv.2021.145302. Epub 2021 Jan 22.
Paddy soil contaminated by cadmium (Cd) has attracted worldwide attention, while foliar spraying of zinc (Zn) could be considered a cost-effective and practical agronomic measure for reducing Cd accumulation in rice grain. However, the effects due to foliar spraying of Zn on different cultivars, as well as the mechanism of subsequent processes taking place are not fully understood up to now. To go a step ahead, a field experiment was conducted with the aim of studying the capability of foliar application of Zn (0.4% ZnSO) to reduce Cd concentration in grain in five late rice cultivars (here named JLYHZ, FYY272, JY284, CLY7 and LXY130), and the antioxidant activities and subcellular distribution of Cd in the leaves. The results indicate that foliar Zn application significantly decreased grain yield in JY284, CLY7 and JLYHZ, compared to controls. In addition, foliar application of Zn significantly decreased Cd concentration in grain of the five rice cultivars, while increased Zn concentration. The effect of foliar application of Zn on transport coefficients of Cd varied greatly for the different rice cultivars. Foliar application of Zn significantly decreased the malondialdehyde (MDA) concentration in rice leaves, and increased peroxidase (POD) activity. Also, it changed the distribution of Cd in the soluble fraction in leaves (expressed as proportion), which was significantly decreased, and the proportion of Cd in the cell wall increased. The structural equation model (SEM) revealed the positive effects of flag leaf Cd, first node Cd, old leaf Cd, and root Cd concentration on grain Cd concentration. Flag leaf Cd had the highest standardized total effects on grain Cd concentration, followed by old leaf Cd. These results indicated that foliar application of Zn was effective in reducing grain Cd concentration of late rice by enhancing antioxidant activities and Cd chelation onto cell wall of leaves, and reducing Cd concentrations in leaves.
被镉（Cd）污染的水稻田引起了全世界的关注，而叶面喷施锌（Zn）被认为是一种经济有效的农业措施，可以减少水稻籽粒中 Cd 的积累。然而，叶面喷施 Zn 对不同品种的影响以及随后发生的过程的机制迄今尚未完全了解。为了更进一步，进行了一项田间试验，目的是研究叶面喷施 Zn（0.4%ZnSO）降低 5 个晚稻品种（分别命名为 JLYHZ、FYY272、JY284、CLY7 和 LXY130）籽粒中 Cd 浓度的能力，以及叶片中 Cd 的抗氧化活性和亚细胞分布。结果表明，与对照相比，叶面喷施 Zn 显著降低了 JY284、CLY7 和 JLYHZ 的籽粒产量。此外，叶面喷施 Zn 显著降低了 5 个水稻品种的籽粒 Cd 浓度，同时增加了 Zn 浓度。叶面喷施 Zn 对不同水稻品种 Cd 转运系数的影响差异很大。叶面喷施 Zn 显著降低了水稻叶片中的丙二醛（MDA）浓度，提高了过氧化物酶（POD）活性。同时，它改变了叶片中 Cd 在可溶部分的分布（表示为比例），显著降低，细胞壁中 Cd 的比例增加。结构方程模型（SEM）揭示了旗叶 Cd、第一节点 Cd、老叶 Cd 和根 Cd 浓度对籽粒 Cd 浓度的正向影响。旗叶 Cd 对籽粒 Cd 浓度的标准化总效应最高，其次是老叶 Cd。这些结果表明，叶面喷施 Zn 通过增强抗氧化活性和叶片细胞壁对 Cd 的螯合作用，以及降低叶片中的 Cd 浓度，有效降低了晚稻籽粒中的 Cd 浓度。
