Soil‐Test Methods for Florida Sands Treated with an Aluminum–Water Treatment Residual and Various Phosphorus Sources

Use of aluminum (Al)–rich water treatment residuals (Al‐WTR) has been suggested as a practice to immobilize excessive phosphorus (P) in Florida soils that could represent an environmental hazard. Fertilizer P requirements can differ in WTR‐amended and unamended soil, so careful selection of soil‐testing methodology is necessary. Acidic extractants can dissolve WTR sorbed P and overestimate plant‐available P. We evaluated the suitability of the Mehlich 1 P (M‐1P) and other agronomic soil‐test procedures in an Al‐WTR‐treated Florida soil. Bahiagrass (paspalum notatum Fluggae), ryegrass (Lolium perenne L.), and a second bahiagrass crop were grown in succession in a Florida topsoil amended with four sources of P at 44 kg P ha^?1 (P‐based rates) and 179 kg PAN ha^?1 [nitrogen (N)–based rates] and three WTR rates (0, 10, and 25 g kg^?1 oven‐dry basis). Both water‐extractable P (WEP) and iron (Fe) strip P (ISP), but not M‐1P, values of soil sampled at planting of each grass were greater in the absence than in the presence of WTR. Total plant P uptake correlated with WEP (r² = 0.82^***) and ISP (r² = 0.75^***), but not M‐1P (r² = 0.34^***). Correlations of the dry‐matter yield, P concentration, and P uptake of the first bahiagrass were also better with WEP and ISP than with M‐1P values. However, regression of plant responses with M‐1P improved after the first crop of bahiagrass. Both WEP and ISP values were better predictors of available soil P than M‐1P in a field study with same four P sources surface applied to established bahiagrass at the same two P rates, with and without WTR. Both WEP and ISP are recommended as predictors of P adequacy in soils treated with WTR, especially for soils recently (< 5 months) treated with Al‐WTR.     

浙江省慈溪市面粉类早点中铝含量研究分析

[目的]了解浙江省慈溪市在售面粉类早点中铝残留状况。[方法]于2014、2015年在慈溪市20个乡镇街道的早餐店、快餐店、食品超市及流动早餐车中抽取281份包子馒头和油条样品;同时,在各乡镇粮油店、超市共抽取30份小麦粉样品。按照GB/T 5009.182-2003《面食制品中铝的测定》方法检测,结果采用SPSS统计学软件分析。[结果]78批油条样品中,铝残留检出率为71.8%,超过100mg/kg的样品为33.3%,铝残留中位数为28.0 mg/kg,最高检出值为290.0 mg/kg,两年度间不存在显著差异。203份包子馒头样品中,铝残留检出率为33.0%,铝残留中位数为0 mg/kg,最高检出值为293.0 mg/kg,两年间存在显著差异。30份小麦粉样品铝残留均未检出。[结论]面粉类早点加工过程中使用含铝膨化剂导致食品中铝残留。     

Aluminum Tolerance in Sunflower Plants Is Associated with Phosphorus Content in the Roots

Sunflower is considered one of the most promising crops for agro-industry development. This plant is adaptable to different soil and climate conditions but is very sensitive to aluminum (Al). Considering that the different plant species have developed different mechanisms to cope with Al, this work evaluated the effect of Al stress on plant growth and nitrogen (N), phosphorus (P), and potassium (K) contents in 25 sunflower genotypes. The results showed that Catissol, EXP 11-26, HLA 860 HO, and H 358 were the most Al-tolerant and IAC-Uruguai, AG 960, EXP 44-49, IAC-Iarama, BRS G27, EXP 887, and H 251 were the most Al-sensitive. We also observed that maintenance of P content in roots of stressed plants seems to play an important role in Al-stressed sunflower plants, suggesting that it could be used as a physiological marker during the screening for Al tolerance in this species.     

植物铝毒害的产生及防治研究进展

土壤中的活性铝积累到一定程度时,即对植物产生毒害。土壤酸化是引起活性铝浓度增加的主要原因。土壤的酸度、富铝化程度、阳离子交换量、有机质含量、微生物种群和数量等因素都会影响到土壤中活性铝的释放,而增加钙的供应、施入有机质、增施磷肥或硅酸、种植牧草和绿肥、接种菌根菌剂、选育和种植耐铝植物等可防治铝对植物的毒害。     

Effects of vegetation history on distribution of Al in surface soils of suburban forests in Aichi Prefecture, Japan

This study examined the distribution of water-extractable Al in soils from forest sites near Nagoya in Aichi Prefecture. The mean concentrations of water-extractable Al in surface soils varied markedly among sites, with the values at site FGB (126 mg/kg) higher than those at sites FG (11.8 mg/kg) and FCB (33.8 mg/kg). Comparisons of the acid buffer capacity of vegetation at the sites revealed that forest cover has a higher capacity for neutralization than the denuded state. We found that the effects of acidic accumulation in the surface soils of suburban forests might depend on vegetation history, and that forest soils that once had no vegetation cover accumulated labile Al due to acidification. The phenomenon was particularly distinct on granite bedrock.     

低分子量有机酸对土壤中铝的化学行为的影响

本文从Al在土壤中的水解-沉淀、吸附-解吸、活化、迁移、降低毒性以及对含Al矿物的表面性质的影响等方面综述了低分子量有机酸对Al的化学行为的影响,并提出了今后需要进一步加强研究的一些方面。     

生物措施缓解酸性土壤铝毒害研究进展

酸性土壤在世界上广泛存在,Al毒是酸性土壤限制作物生长和产量的主要限制因子之一.本文概述了酸性土壤Al毒害问题以及作物的耐Al机制,总结了遗传改良植物的耐Al性、向土壤或植物根际接种外生菌根真菌和其他耐Al微生物以缓解酸性土壤Al毒害的研究进展.以上措施在酸性土壤中的生态系统恢复具有应用前景.     

四季豆根边缘细胞特性及铝对其活性的影响

以四季豆为研究材料,研究了四季豆根边缘细胞数目和存活率的变化及不同浓度铝对四季豆根边缘细胞的影响。结果表明:不同长度根洗脱下来的边缘细胞数目存在差异,其中10mm根的边缘细胞数目达到最大值;随着铝浓度的提高,边缘细胞的存活率明显下降;铝胁迫下短时间内(6h)边缘细胞可保持较高的活性,但6h后,边缘细胞活性迅速降低。     

Effect of cyclooxygenase 2 on hippocampal neuronal damage induced by aluminum in rats

AIM:To study the relationship between cyclooxygenase 2(COX-2) and the damage of hippocampal neurons by aluminum overload in rats. METHODS:Newborn SD rats(less than 24 h) were used to establish the model of primary culture of hippocampal neurons. The neurons were treated with aluminum at concentration of 200 μmol/L. The techniques of RNA interference(RNAi) and cell transfection were used to study the role of COX-2 in hippocampal neuron. Following RNAi by cell transfection, Western blotting analysis was used to determine the protein expression of COX-2. Cell growth was assayed by the method of MTT. The pathological changes of the neurons were observed by fluorescence labeling. The activity of superoxide dismutase(SOD) and lactate dehydrogenase(LDH), and the content of malondialdehyde(MDA) were detected for evaluating cell damage. RESULTS:COX-2 RNAi by cell transfection significantly decreased the protein expression of COX-2 without changing the neuronal pathomorphology, cell viability, SOD activity and MDA content. However, it obviously improved livability and SOD activity of the hippocampal neurons, which were aluminum-overloaded. Inhibition of COX-2 expression also reduced the leakage of LDH and the content of MDA, and ameliorated the pathological changes in neurons. CONCLUSION:Moderate silence of COX-2 expression not only significantly affects the morphological changes and physiological functions of hippocampal neurons, but also prevents the neurons from aluminum-induced damages.     

黄瓜根边缘细胞生物学特性及其对铝的响应

 以黄瓜为试验材料, 研究了黄瓜根边缘细胞的生物学特性及其对铝毒的响应。试验结果表明,在黄瓜种子萌发过程中, 根边缘细胞有很高的活性。当根长度在25 mm, 根边缘细胞数目达到最高值5 480个, 根伸长到10 mm时, PME (果胶甲基酯酶) 相对活性达到最高值, 然后随着根的伸长, PME相对活性逐渐下降。在铝处理的条件下, 黄瓜根长及边缘细胞的存活率会随着铝液浓度的升高依次递减, 说明铝毒对根的发育有明显的抑制作用及危害, 而根冠的PME活性却有所提高, 说明了PME与植物铝毒胁迫之间存在着相关性。铝毒条件下边缘细胞PME活性的提高, 使细胞壁的果胶去甲基化, 增加了Al³⁺的结合位点, 从而避免铝更多地进入细胞内, 造成对植物的毒害。