不同水分管理模式对镉在水稻植株体内迁移与累积的影响

发布时间：2018-03-28 20:26

本文选题：水分管理　切入点：灌溉水　出处：《中南林业科技大学》2017年硕士论文

【摘要】：本研究通过盆栽试验,探明不同水分管理模式对水稻体内Cd迁移与累积的影响。向土壤添加外源Cd使之达到5 mg·kg-1(编号A)和10 mg·kg-1(编号B)的污染水平,通过盆栽试验研究4种不同水分管理模式(水稻全生育期湿润灌溉(M)、灌浆期湿润和灌浆期后淹水灌溉(M-F)、灌浆期淹水和灌浆后湿润灌溉(F-M)、全生育期淹水灌溉(F))在水稻不同生育期(分蘖盛期、灌浆期、成熟期)对土壤氧化还原电位(Eh值)、土壤Cd的生物有效性、水稻各部位Cd含量以及水稻体内Cd转运系数和富集系数的影响,系统研究了土壤Eh值与水稻各部位Cd含量的相关关系,同时还探讨了土壤含水率对水稻吸收Cd的影响。主要研究结果如下:(1)M处理使土壤Eh值始终保持较高水平,土壤处于氧化状态;F处理使土壤Eh值保持较低水平,土壤处于还原状态;灌浆期开始后,M-F处理的土壤Eh值急剧降低,而F-M处理的土壤Eh值急剧上升。土壤交换态Cd含量和土壤Cd的TCLP提取态含量随着水稻生育期的延长而降低。(2)与M处理相比,F-M、M-F、F处理能显著降低水稻根、茎叶、谷壳、糙米中Cd含量。A污染程度下,在M-F和F处理下,糙米中Cd含量分别为0.19 mg·kg-1和0.10 mg·kg-1,均低于国家食品中污染物限量标准0.20 mg·kg-1的限制。B污染程度下,在F处理下,糙米中Cd含量为0.07 mg·kg-1,低于国家食品中污染物限量标准0.20 mg·kg-1的限制。(3)4种水分管理模式对Cd从根到茎叶转运系数的影响最显著,其转运系数TF茎叶/根大小关系均为:TFMTFF-MTFM-FTFF。同一水分管理模式下,水稻植株体内各部位Cd转运系数的大小顺序为:TF茎叶/谷壳/T谷壳/糙米TF根/茎叶。(4)4种水分管理模式下水稻根、谷壳、糙米的Cd富集系数的大小顺序均为:BCFMBCFF-MBCFM-FBCFF。(5)两种污染程度下,土壤Eh值与水稻各部位Cd含量均呈显著或极显著相关关系。土壤Eh值为50～75 mV可能是水稻急剧积累Cd的阈值范围,将土壤Eh值控制在50 mV以下,能大量减少水稻植株对Cd的吸收和累积。(6)随着土壤含水率的增加,土壤Eh值和土壤有效态Cd含量均逐渐降低。土壤处于中Cd污染程度,土壤含水率大于80%时,糙米中Cd含量显著降低。
[Abstract]:The effects of different water management models on CD transport and accumulation in rice were investigated by pot experiment. The pollution levels of 5 mg kg-1 (No. A-1) and 10 mg kg-1 (number B) were increased by adding exogenous CD to the soil. Pot experiment was conducted to study four different water management models (wet irrigation in whole growing period, wet irrigation in filling stage, water flooded irrigation in filling stage, wet irrigation in filling stage and wet irrigation after filling stage, and flooded irrigation in whole growth period). Different growth stages (full tillering stage) of rice, The effects on soil redox potential (Eh), bioavailability of CD in soil, CD content in different parts of rice, CD transport coefficient and enrichment coefficient in rice were studied. The relationship between soil Eh value and CD content in different parts of rice was systematically studied. The effects of soil moisture content on CD uptake by rice were also discussed. The soil Eh value was kept low and the soil was reduced after the filling stage, and the Eh value of the soil treated with M-F decreased sharply after the filling stage. However, the soil Eh value of F-M treatment increased sharply, the content of soil exchangeable CD and the content of TCLP extract of soil CD decreased with the prolongation of rice growth period. (2) compared with M treatment, the content of soil Eh in F-M treatment decreased significantly compared with that of M treatment, and the content of soil exchangeable CD and the content of soil CD extract decreased significantly, compared with M treatment, the rice root, stem and leaf, and grain hull. The CD content in brown rice was 0.19 mg kg-1 and 0.10 mg kg-1 under M-F and F treatments, respectively, which was lower than that of 0.20 mg kg-1 in national food pollutant limit standard, and under F treatment, the content of CD in brown rice was 0.20 mg / kg ~ (-1) and 0.20 mg / kg ~ (-1) respectively under M-F and F treatments. The CD content in brown rice was 0.07 mg / kg ~ (-1), which was lower than the limit of 0.20 mg kg-1 in national food pollutant limit. The effect of four water management modes on CD transport coefficient from root to stem and leaf was most significant. Under the same water management mode, the order of CD transport coefficient in different parts of rice plant was as follows: 1. The order of CD transport coefficient in different parts of rice plant was: t / T grain hull / brown rice TF root / stem / leaf. The CD enrichment coefficient of grain husk and brown rice were all in the order of 1: BCFMBCFF-MBCFM-FBCFF.5), the soil Eh value was significantly or extremely correlated with CD content in all parts of rice, and the soil Eh value of 500.75mV might be the threshold range of rapid accumulation of CD in rice. If the soil Eh value was controlled below 50 MV, the CD uptake and accumulation of rice plants could be greatly reduced.) with the increase of soil moisture content, the soil Eh value and the soil available CD content decreased gradually, and the soil was in the CD pollution degree. When soil moisture content was greater than 80%, CD content in brown rice decreased significantly.
【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S511;X56

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