淮南矿区不同植物重金属修复能力研究

土壤重金属污染是当今面临的一个较为重要环境问题,而土壤重金属污染的植物修复则是治理污染环境的重要手段之一,以淮南市某煤矿复垦区为例,根据不同植物的重金属富集系数及其转移系数,研究分析不同植物对不同重金属的富集能力;结果表明:车前草对Cu、Ni、Cd、Hg和As元素的富集能力较强,狗尾巴草对As、Ni和Cd元素有较强的富集能力;苦苣菜对Cu、Mn、Ni、Cd、Hg和As元素具有较强的富集能力;芦苇对Cu、Ni、Cd和Hg元素的富集能力较强;车前草、狗尾巴草对Hg元素的转移能力强;苦苣菜对重金属元素的转移能力较差;芦苇对重金属元素(除了Ni以外)的具有较强转移能力。     

镉胁迫对水稻颖果充实和生理活性的影响

通过盆栽试验探讨Cd^2＋胁迫对扬稻6号和粳稻941颖果充实和生理活性的影响,结果表明：Cd^2＋胁迫降低颖果呼吸速率、光合速率以及ATP含量;降低颖壳和果皮叶绿素含量;使颖果灌浆速率减慢,鲜干重增加的速率减缓,灌浆的天数变短,最终成熟颖果干重降低。说明Cd^2＋胁迫降低颖果呼吸活性、能量物质以及其它生理活性,从而降低颖果的代谢活性和发育时间,最终导致贮藏物质的合成和积累量降低。     

豫灵冶炼厂周边土壤重金属污染及植物重金属累积特征研究

了解豫灵土壤污染现状和筛选重金属富集植物对污染土壤进行修复,采用火焰原子吸收光度法对豫灵冶炼厂周边土壤中重金属含量进行了测定,并对7种植物铅、镉的吸收和富集能力进行了研究,结果表明：豫灵冶炼厂周边土壤中Pb、Cd的含量严重超标,分别为821.574mg/kg和62.207mg/kg。采集的7种植物样品对Pb、Cd的吸收能力存在明显差异,苦荬菜、茵陈蒿和播娘蒿对Pb、Cd的吸收能力均较强,植物体内Pb的含量分别为423.95、358.275和303.5mg/kg,Cd的含量分别为54.60、49.425、55.175mg/kg。茵陈蒿和播娘蒿属于杂草,适应性强,利用其对矿区土壤进行修复,不经人工干预即可正常生长,成本较低,因此可作为该污染区土壤修复的选择物种。     

Accumulation and distribution of arsenic and cadmium by tea plants

It is important to research the rules about accumulation and distribution of arsenic and cadmium by tea plants, which will give us some scientific ideas about how to control the contents of arsenic and cadmium in tea. In this study, by field inves- tigation and pot trial, we found that mobility of arsenic and cadmium in tea plants was low. Most arsenic and cadmium absorbed were fixed in feeding roots and only small amount was transported to the above-ground parts. Distribution of arsenic and cadmium, based on their concentrations of unit dry matter, in tea plants grown on un-contaminated soil was in the order: feeding roots>stems≈main roots>old leaves>young leaves. When tea plants were grown on polluted soils simulated by adding salts of these two metals, feeding roots possibly acted as a buffer and defense, and arsenic and cadmium were transported less to the above- ground parts. The concentration of cadmium in soil significantly and negatively correlated with chlorophyll content, photosyn- thetic rate, transpiration rate and biomass production of tea plants.     

Effects of ammonium application rate on uptake of soil adsorbed amino acids by rice

In recent years, excessive use of chemical nitrogen (N) fertilizers has resulted in the accumulation of excess ammonium (NH ₄ ⁺ ) in many agricultural soils. Though rice is known as an NH ₄ ⁺ -tolerant species and can directly absorb soil intact amino acids, we still know considerably less about the role of high exogenous NH ₄ ⁺ content on rice uptake of soil amino acids. This experiment examined the effects of the exogenous NH ₄ ⁺ concentration on rice uptake of soil adsorbed glycine in two different soils under sterile culture. Our data showed that the sorption capacity of glycine was closely related to soils;’ physical and chemical properties, such as organic matter and cation exchange capacity. Rice biomass was significantly inhibited by the exogenous NH ₄ ⁺ content at different glycine adsorption concentrations. A three-way analysis of variance demonstrated that rice glycine uptake and glycine nutritional contribution were not related to its sorption capacity, but significantly related to its glycine:NH ₄ ⁺ concentration ratio. After 21-d sterile cultivation, the rice uptake of adsorbed glycine accounted for 8.8%;–22.6% of rice total N uptake, which indicates that soil adsorbed amino acids theoretically can serve as an important N source for plant growth in spite of a high NH ₄ ⁺ application rate. However, further studies are needed to investigate the extent to which this bioavailability is realized in the field using the ¹³C, ¹⁵N double labeling technology.     

Organic nitrogen components in soils from southeast China

Objective:To investigate the amounts of extractable organic nitrogen(EON),and the relationships between EON and total extractable nitrogen(TEN),especially the amino acids(AAs) adsorbed by soils,and a series of other hydrolyzed soil nitrogen indices in typical land use soil types from southeast China.Under traditional agricultural planting conditions,the functions of EON,especially AAs in the rhizosphere and in bulk soil zones were also investigated.Methods:Pot experiments were conducted using plants of pakchoi(Brassica chinensis L.) and rice(Oryza sativa L.).In the rhizosphere and bulk soil zone studies,organic nitrogen components were extracted with either distilled water,0.5 mol/L K2SO4or acid hydrolysis.Results:K2SO4-EON constituted more than 30% of TEN pools.K2SO4-extractable AAs accounted for 25% of EON pools and nearly 10% of TEN pools in rhizosphere soils.Overall,both K2SO4-EON and extractable AAs contents had positive correlations with TEN pools.Conclusions:EON represented a major component of TEN pools in garden and paddy soils under traditional planting conditions.Although only a small proportion of the EON was present in the form of water-extractable and K2SO4-extractable AAs,the release of AAs from soil exchangeable sites might be an important source of organic nitrogen(N) for plant growth.Our findings suggest that the content of most organic forms of N was significantly greater in rhizosphere than in bulk soil zone samples.However,it was also apparent that the TEN pool content was lower in rhizosphere than in bulk soil samples without added N.     

Characterization of (68)Zn uptake, translocation, and accumulation into developing grains and young leaves of high Zn-density rice genotype

Zinc (Zn) is an essential micronutrient for humans, but Zn deficiency has become serious as equally as iron (Fe) and vitamin A deficiencies nowadays. Selection and breeding of high Zn-density crops is a suitable, cost-effective, and sustainable way to improve human health. However, the mechanism of high Zn density in rice grain is not fully understood, especially how Zn transports from soil to grains. Hydroponics experiments were carried out to compare Zn uptake and distribution in two different Zn-density rice genotypes using stable isotope technique. At seedling stage, IR68144 showed higher ⁶⁸Zn uptake and transport rate to the shoot for the short-term, but no significant difference was observed in both genotypes for the long-term. Zn in xylem sap of IR68144 was consistently higher, and IR68144 exhibited higher Zn absorption ratio than IR64 at sufficient (2.0 μmol/L) or surplus (8.0 μmol/L) Zn supply level. IR64 and IR68144 showed similar patterns of ⁶⁸Zn accumulation in new leaves at seedling stage and in developing grains at ripening stage, whereas ⁶⁸Zn in new leaves and grains of IR68144 was consistently higher. These results suggested that a rapid root-to-shoot translocation and enhanced xylem loading capacity may be the crucial processes for high Zn density in rice grains.     

Targeted yield concept and a framework of fertilizer recommendation in irrigated rice domains of subtropical India

Soil test crop response （STCR） correlation studies were carried out in Vindhyan alluvial plain during 2001 to 2004 taking IR-36 as test crop to quantify rice production in the context of the variability of soil properties and use of balanced fertilizers based on targeted yield concept. The soils were developed on gently sloping alluvial plain with different physiographic settings and notable variation in drainage condition. Soil properties show moderate variation in texture （loamy to clay）, organic carbon content （4.4 to 9.8 g/kg）, cation exchange capacity （10,2 to 22.4 cmol （p＋）/kg） and pH （5.3 to 6,4）, Soil fertility status for N is low to medium （224 to 348 kg/ha）, P is medium to high （87 to 320 kg/ha） and K ranges from medium to high （158 to 678 kg/ha）. Database regarding nutrient requirement in kg/t of grain produce （NR）, the percent contribution from the soil available nutrients [CS （%）] and the percent contribution from the applied fertilizer nutrients [CF （%）] were computed for calibrating and fbrmulating fertilizer recommendations. Validity of the yield target for 7 and 8 t/ha was tested in farmers＇ fields and yields targets varied at less than 10%. The percent achievement of targets aimed at different level was more than 90%, indicating soil test based fertilizer recommendation approach was economically viable within the agro-ecological zone with relatively uniform cropping practices and socio-economic conditions.