玉米生理年龄的差异对N缺乏诊断的影响

Many studies have shown that chlorophyll meter readings （CMRs） can be used to diagnose deficiencies of nitrogen （N） during the growth of corn （Zea mays L.） in small-plot trials, but there is need to address additional problems encountered when diagnoses are made in fields of the size managed in production agriculture. A noteworthy difference between smallplot trials and production agriculture is the extent to which the effects of N are confounded with the effects of other factors such as tillage, landscape, soil organic matter and moisture content. We illustrate how some of these factors can cause differences in the physiological age of plants and introduce errors in the diagnoses of N deficiencies. We suggest methods （measuring the height to the youngest leaf collar and assigning leaf numbers by using the first leaf with pubescence and the ear leaf as references to identify growth stages） for minimizing these errors. The simplified method of growth stage identification can be used to select appropriate plants and leaves for making diagnoses in fields and to distinguish the effects of N from the effects of other factors that influence plant growth.     

Metal contamination from open-cast copper and sulphur mining in southeast Ireland

The metal content was determined in soil and vegetation around the eastern zone of the disused sulphur and copper mines at Avoca (southeast Ireland). A 250 m × 250 m grid survey was conducted covering a total area of 4 km². The mining belt was in the centre of the investigated site and was sampled separately. Iron, Zn, Cu and Cd concentrations in soil and plant material were determined, in addition to soil organic matter content and soil pH. Soil samples taken from the spoil showed elevated Cu and Cd concentrations, and low soil pH and organic matter content. At least 50 per cent of the agricultural sites examined around the East Avoca Mine showed elevated soil Cu and Cd concentrations, whereas Zn and Fe soil concentrations were within the range for unpolluted soils. None of the vegetation analysed had elevated Zn, Cd, Fe or Cu concentrations. Overall there was no indication of serious metal contamination in either soils or vegetation surrounding the mine in spite of extensive dust deposition during open-pit mining activity 15–30 years ago. However, a plume of elevated Cu in the soil was identified, which originated from a large spoil heap and had been spread for some 2·0 km by the prevailing wind.     

饲料中高水平铜对草鱼生长、肝胰脏和肌肉中铜铁锌含量的影响*

 摘要：研究饲料中铜对草鱼生长性能、肝胰脏和肌肉中铜铁锌含量的影响,为饲料中铜的安全添加提供理论依据。用铜含量分别为9.38(对照),28.17,46.21,80.07,208.54,439.50,679.72,873.37,1 365.42mg/kg的试验饲料,饲喂初始体重（25.57 ± 0.47）g的草鱼56d,每14d取样1次。结果表明：饲料铜含量对草鱼的成活率、特定生长率、饲料系数、鱼体水分、鱼体粗脂肪和鱼体粗灰分无显著影响(P＞0.05);而饲料铜含量≥87337mg/kg时,鱼体粗蛋白含量显著低于对照组(P＜0.05)。随着饲料铜含量的升高,草鱼肌肉铜含量无显著变化(其含量为1.52~1.65mg/kg),铁含量显著升高,锌含量则仅在14d时显著降低;肝胰脏铜含量显著升高,56d时,在铜含量1 365.42mg/kg的试验组达到22.97mg/kg;肝胰脏铁含量14d时显著升高,但在56d时呈先升高后降低趋势;肝胰脏锌含量在14d时显著降低,而在56d时,饲料铜含量≥439.50mg/kg的试验组显著高于对照组(P＜0.05)。在本试验条件下,草鱼肝胰脏和肌肉中铜含量均低于我国水产品相关标准中规定的铜的限量。     

Inhibitors of methane production in paddy soils

Global warming is now attracting the world attention. Methane is an important greenhouse gas next to CO₂. Prather et al. (1995) estimated that rice paddy fields account for 14% of all biogenic atmospheric methane. It is considered that methane production from rice paddy fields is increasing along with the increase of the population. Therefore, the development of rice cultivation techniques for reducing methane production is essential, in order to preserve the global environment.     

福建若干山地土壤不同形态氧化铁的主组元分析

研究福建4条代表性山地土壤垂直带谱中铁的形态的结果表明,氧化铁的活化度和游离度随海拔升高而呈现规律性的变化,应用主组元分析法,前两个主组元全铁和游离铁的累计贡献率已达85％以上。据此认为,氧化铁的活化度可以作为划分常湿润铁铝土亚纲和湿润铁铝土亚纲的一项参考依据。     

不同耕作制下水田土壤有机质氧化铁含量的研究

以第四纪红色粘土发育的旱土为供试土壤,淹水种稻,进行水田耕作制模拟试验,研究对土壤有机质、氧化铁含量的影响。结果表明:有机质的增加是冬泡区>冬绿区>冬油区,但只施化肥的冬泡区有机质增加量少;无定形铁的含量及氧化铁的活化度均逐年增加,其增加速度是冬泡区>冬绿区>冬油区:无定形铁含量与有机质含量之间存在一定的相关性。     

污灌水中的铁对土壤性质和水稻生长的影响

以污灌水形式带入农田的铁对水稻影响的研究报道尚少。本文通过水稻盆栽试验,研究不同浓度的含铁污水对土壤pH值、水溶性及交换性亚铁含量和水稻植株含铁量、生长状况及产量的影响。结果表明,在两造的时间内,当污灌水含铁1000ppm以上时减产显著,污灌水含铁600～800ppm时有减产的趋势,污灌水含铁600ppm以下时对产量没有显著影响。水稻亚铁中毒时从老叶叶鞘中部开始发病。晚造糙米含铁量为早造的4～9倍。     

几种土壤中不同形态铁及无定形硅铝的比较研究

分析研究白浆土、黑土和草甸土三类土壤不同形态铁和无定形硅铝表明,游离氧化铁的量在各类土中均为表层大于底层;铁的活化度白浆土高于黑土,而白浆土的白浆层又高于腐殖质层和淀积层;无定形硅、铝在白装土中层次之间分异明显,说明有淋淀现象发生,在黑土和草甸土中差异不大;新鲜有机质对铁的活化有显著作用,络合态铁和土壤腐殖质含量呈明显的正相关。     

有机硫影响稻田土壤甲基汞的产生

为了探讨有机硫化合物在无机汞甲基化过程中所起的作用,以泉州市某企业周边的汞污染稻田土壤为试验材料,以还原型谷胱甘肽为有机硫,采用室内土壤模拟试验的方法,研究了3个浓度(0、500、1 000 mg·kg~(-1))的有机硫施加对土壤中汞甲基化及甲基汞生物有效性的影响。结果表明:和对照组相比,谷胱甘肽添加显著提高了土壤中铁、锰的溶出以及土壤中可溶性碳的含量。此外,谷胱甘肽施用也显著提高了土壤中甲基汞的产生和甲基汞的溶出,对土壤固相中甲基汞的增加率为87.36%～212.48%,对土壤溶液中甲基汞的增加率为4 380.00%～5 890.30%。相关性分析和逐步回归模型表明,土壤中可溶性铁的含量是影响汞甲基化和甲基汞生物有效性的关键因子。研究表明,有机硫促进了汞甲基化,有机硫化合物影响汞甲基化过程不只是有机硫和汞的络合作用,土壤中铁、锰氧化物所起的作用也不容忽视。     

铁、锰胁迫对人参叶片某些生理特征的影响

为了明确铁、锰胁迫对人参生长和生理的影响规律,本试验在Hoagland营养液配方的基础上设定铁、锰胁迫浓度,研究了人参开花期叶片中相应的生理变化.结果表明,高铁胁迫下,叶绿素a、叶绿素b、类胡萝卜素含量均有下降的趋势,其在CFe(0.215 2 mmol/L)胁迫下是正常处理的0.71,0.30,0.33倍,且均与正常水平呈显著差异(P＜0.05),过氧化物酶(POD)活性、可溶性糖及脯氨酸含量呈增加趋势,POD活性为正常处理的4倍,可溶性糖含量是正常处理的14.63倍,脯氨酸含量增加了51.77μg,/g;高锰胁迫下,叶绿素a、叶绿素b、类胡萝卜素含量变化趋势与高铁胁迫基本一致,其在CMn(0.038 mmol/L)胁迫下是正常处理的0.55,0.78,0.13倍,均达到了显著差异(P＜0.05),POD活性为正常处理的2.78倍,可溶性糖含量是正常处理的1.86倍,脯氨酸含量增加了76.42 μg/g.低铁、锰胁迫下,叶绿素a、叶绿素b、类胡萝卜素含量均表现为升高的趋势;POD活性呈降低趋势;可溶性糖含量显著降低;脯氨酸含量明显升高.铁、锰胁迫下,造成人参氧化损伤,光合作用下降,体内积累大量的渗透调节物质.