颗粒有机质对水稻镉吸收及转运的影响

采用盆栽试验,通过测定不同颗粒有机质(POM)添加量下土壤、POM中有机碳(POM-C)和Cd(POM-Cd)含量及水稻各部位Cd含量,研究了POM对紫色水稻土水稻镉吸收的影响及机制.结果表明:添加POM提高了土壤有机碳(SOC)、溶解性有机碳(DOC)、POM-C、POM-Cd、POM对Cd的富集系数和土壤有效Cd含量,在POM添加量达2. 5 g·kg~(-1)时可显著提高土壤POM-C和POM-Cd比例.添加POM提高了水稻植株生物量及Cd在水稻植株中的总累积量,但使水稻根Cd含量降低24%～42%,茎叶Cd含量提高9%～30%,籽粒Cd含量在POM添加量为0. 5 g·kg~(-1)和1. 0 g·kg~(-1)时分别降低了17%和36%,添加量为2. 5 g·kg~(-1)时提高了39%.添加POM对Cd在水稻根和茎叶中的分配不显著,但POM添加量较少时可抑制Cd从水稻茎叶向籽粒转运,POM添加达到一定量时,促进Cd从茎叶向籽粒转运,最终提高籽粒中Cd含量.相关分析结果表明,土壤有效Cd是影响茎叶Cd累积的主要因素,POM-Cd总量是影响籽粒中Cd累积的主要因素.因此,添加POM可通过改变土壤SOC、DOC、POM-C、POM-Cd及有效镉含量,影响水稻对Cd的吸收.

Effect of Particulate Organic Matter on Cadmium Uptake and Transport in Rice

A pot experiment was carried out to investigate the effects and mechanism of particulate organic matter (POM) on cadmium uptake of rice on purple paddy soil. Organic carbon content in soil and POM and Cd content in POM and rice were analyzed. The results showed that the contents of total soil organic carbon (SOC), dissolved organic carbon (DOC), organic carbon in POM (POM-C), Cd in POM (POM-Cd), and the Cd enrichment factor in POM increased with the application of POM. When POM was applied at a rate of 2.5 g·kg^-1, the proportion of POM-C and POM-Cd in soil significantly increased. Application of POM also increased rice plant biomass and enhanced the accumulation of Cd in rice. The Cd content was reduced by 24%-42% in rice roots and increased by 9%-30% in rice shoots with POM application, whereas it was reduced by 17% and 36% in rice grains when the application of POM was 0.5 g·kg^-1 and 1.0 g·kg^-1, respectively, but increased by 39% when the application of POM was 2.5 g·kg^-1. Application of POM had no significant effect on the distribution of Cd in rice roots and shoots, but significantly affected the distribution of Cd in rice grains. The transportation of Cd from shoots to grains was inhibited at low rates of POM, but was promoted at high rates of POM, and consequently increased the Cd content in rice grains. Correlation analyses showed that the content of soil available Cd was the main factor affecting Cd accumulation in rice shoots, and the total content of POM-Cd in soil was the main factor affecting Cd accumulation in rice grains. Therefore, the addition of POM to soil could affect the Cd uptake of rice by changing the content of SOC, DOC, POM-C, POM-Cd, and available Cd in paddy soil.