Synthetic Iron Chelates as Substrates of Root Ferric Chelate Reductase in Green Stressed Cucumber Plants

This work studied the behavior of different iron (Fe)-chelates as substrates of ferric chelate reductase (FCR) and their ability as Fe suppliers for mildly chlorotic plants. FCR activity and Fe concentration in xylem sap were determined in green stressed cucumber plants with different stress levels using different synthetic chelates as substrates. Both reduction and Fe concentration in the xylem sap were higher for the less-stable Fe chelates, except for Fe-EDTA, which presented a relatively low Fe concentration in sap. It was concluded that a high stability of the chelate in the nutrient solution reduces the Fe reduction, but other factors, such as the complexation of the Fe(II) by the chelating agents, should be considered when the complete process of Fe uptake is studied. The use of both indexes together, i.e., FCR determination and xylem sap concentration, is useful for understanding the Fe uptake from different Fe chelates.     

小金海棠Fe3+-还原酶基因MxFRO在酵母中的表达及其活性检测

为研究苹果属植物抗缺铁的分子生物学机理,从铁高效基因型小金海棠（Malus xiaojinensis）中克隆了Fe3+-还原酶基因MxFRO。MxFRO2的cDNA序列长2283bp,开放阅读框为2166bp,编码722个氨基酸。半定量RT-PCR结果表明MxFRO在小金海棠的根和叶中均受缺铁胁迫诱导。 将MxFRO转入野生型酵母中,结果表明转基因酵母的Fe3+-还原酶活性是对照的2.8倍,因此我们初步推测MxFRO基因编码的蛋白具有Fe3+-还原酶活性。     

小金海棠Fe3+-螯合还原酶MxFRO2基因启动子的克隆与表达分析

通过染色体步移法从小金海棠（Malus xiaojinensis）基因组中克隆了三价铁螯合还原酶（ferric chelate reductase, MxFRO2）基因翻译起始位点上游1 738 bp的启动子序列。生物信息学分析表明,该启动子片段中存在光响应元件G-box、生长素应答元件、铜元素响应元件、TATA-box、CAAT-box等顺式作用元件。从TAIR网站获得了拟南芥（Arabidopsis thaliana）中8个FRO基因上游的启动子序列,通过PlantCARE分析了其与MxFRO2启动子的异同。根据在线预测结果,克隆了翻译起始位点上游1 644 bp（MxFul）和259 bp（MxD1）两段序列,构建了其与GFP融合的瞬时表达载体,并将重组质粒通过PEG介导法分别转化拟南芥叶片原生质体,结果表明,小金海棠MxFul和MxD1两段启动子序列都能驱动GFP蛋白在拟南芥原生质体中的瞬时表达。     

小金海棠Fe^3＋-还原酶基因MxFRO在酵母中的表达及Fe^3＋-还原酶活性检测

从铁高效基因型小金海棠(Malus xiaojinensis)中克隆了Fe3 -还原酶基因MxFRO.半定量RT-PCR结果表明MxFRO在小金海棠的根和叶中均受缺铁胁迫诱导.将MxFRO转入野生型酵母(Saccharomyces cerevisitae)中,结果表明转基因酵母的Fe3 -还原酶活性是对照的2.8倍,实验初步证明MxFRO基因编码的蛋白具有Fe3 -还原酶活性.     

淹渍对花椰菜根系活力和叶片光合特性的影响

以上海崇明岛花椰菜品种“崇花120天”为试材,于2014年8-11月人工气候室开展盆栽试验,将花椰菜植株根部分别淹水处理3、6、9、12、15d,以正常灌溉为对照（CK）,测定花椰菜的根系活力和叶片光合参数等指标。结果表明：(1)随着淹渍胁迫时间的延长,花椰菜的根系活力呈不同程度的降低。当淹渍胁迫超过9d后,根系活力趋于0;(2)与CK相比,淹渍胁迫3、6、9、12和15d时,叶片最大净光合速率分别下降4.90%、68.13%、78.71%、90.92%和98.68%,与此同时,光补偿点降低、光饱和点也随之增大;(3)淹渍胁迫下花椰菜气孔导度、蒸腾速率和胞间CO2浓度明显下降,淹渍胁迫初期,气孔限制值增大。说明胁迫初期影响花椰菜净光合速率下降的因素为气孔限制因子。(4)淹渍胁迫前6d各项指标下降明显,之后趋于稳定,可以确定淹渍胁迫第6天为致灾临界指标。     

Effects of Sulfur Fertilization on Soybean Root and Leaf Traits,and Soil Microbial Activity

ABSTRACT

A pot experiment was implemented to study effects of sulfur (S) fertilization on soybean root and leaf traits and soil microbial activity in 2004 and 2005. In this experiment, three different treatments were established: 0 mg· kg^{? 1}(CK), 30 mg· kg^{? 1}(A), and 60 mg· kg^{? 1}(B). The results showed that an application of elemental sulfur significantly increased the number of soybean side roots by 8.6% to 33.2% and dry weight by 6.6% to 34.3%, increased the root nodules number by 2.7% to 35.9%, and dry weight by 13.0% to 75.7%, increased chlorophyll content in leaves by 0.4 to 3.9 unit, and increased soybean yield per plant by 7.3% to 12.8%, compared with the control. The application of elemental sulfur also increased the amount of soil microorganism (bacterium, fungi and actinomycete), activity of catalase, urease, neutral phosphatase, and polyphenoloxidase in the same growth stage significantly. The above results showed sulfur supply could promote the growth of soybean, increase the yield, and enhance soil microbial activity. Thirty mg· kg^{? 1} was the suitable rate of sulfur for achieving the highest yield.     

Effects of the Frequency of Iron Chelate Supply by Fertigation on Iron Chlorosis in Citrus

Abstract

A field experiment was carried out in a drip‐irrigated orchard of Clementine (Citrus clementina Ort. ex. Tan) grafted on Troyer citrange (C. sinensis × Poncirus trifoliata) rootstock located in the Valencian Citrus area (Spain). The trees received a single iron (Fe) EDDHA (ethylene diamine diorthohydroxyphenyl acetate) rate (3 g Fe tree^?1) supplied in different application frequencies from April to September (8‐, 4‐, 2‐, or 1‐week intervals). Leaf chlorophyll (Chl) concentrations were estimated every month by using an SPAD‐502 meter. The foliar contents of Fe were also evaluated with time. Mineral composition of leaves, total Chl concentration, yield, and fruit quality were also evaluated at the end of the assay. SPAD readings, Chl, N, K, Mg, Fe, and Mn concentration in leaves increased as a result of Fe application. The concentration of Zn, however, significantly decreased in comparison to the control trees. Iron treatment increased yield and some of the fruit quality parameters, like total juice, sugar, and acid contents. Iron application frequency had not a consistent effect on the concentrations of macro and micronutrients in leaves, yield, and fruit quality. The highest values of SPAD readings and the leaf Chl content were obtained when Fe was applied at 4‐week intervals along the year. These results suggest that soil Fe‐EDDHA application with a moderate frequency could be recommended to the Citrus farmers in the area for a more rational Fe application along the growth cycle in Citrus orchards.     

Comparison of Various Analysis Methods for Determination of Iron Chlorosis in Apple Trees

Abstract

The objective of this study was to compare iron (Fe) concentrations (mg kg^?1) of the leaves measured by different methods and to determine the most suitable method to be used in evaluation of iron chlorosis in apple trees. For this purpose, green and chlorotic leaves were collected from 76 apple orchards in 1998 and 1999. Iron concentrations (mg kg^?1) of dried leaf samples were measured with 4 different methods, 1 N HCl (Method 1), 0.1 N HCl (Method 2), 0.005 M DTPA (Method 3), and 1.5% o-phenanthroline (Method 4). Total Fe concentrations (mg kg^?1) of dried leaf samples were also analyzed. Total chlorophyll and peroxidase enzyme activity in fresh leaf samples were measured. The total chlorophyll, peroxidase enzyme activity, Fe concentrations (mg kg^?1) determined by Method 1, Method 3, Method 4, and total Fe concentrations (mg kg^?1) of green leaves were higher than those of chlorotic leaves. On the other hand, no significant difference was found between Fe concentrations (mg kg^?1) of green and chlorotic leaves, measured with Method 2. Significant relationship observed amongst chlorophyll concentrations, peroxidase enzyme activity, and Fe concentrations (mg kg^?1) of samples suggests that 1 N HCl method was the most suitable method amongst the methods used in this study for apple trees.     

苹果短链脱氢酶基因MdSDR响应腐烂病菌侵染的功能研究

短链脱氢/还原酶(SDR)是一类NAD(P)(H)依赖的氧化还原酶,负责催化生物体内各种代谢活动的氧化还原步骤。为了探究苹果(Malus domestica)SDR(MdSDR)蛋白的功能,利用农杆菌介导的苹果组培苗瞬时转化技术在苹果叶片中瞬时表达MdSDR,然后通过刺伤接种法研究过表达MdSDR对叶片抗病性的影响;利用实时荧光定量PCR(qRT-PCR)技术检测瞬时表达MdSDR后苹果中脂肪酸生物合成相关基因的表达水平;利用气相色谱分析技术检测瞬时表达MdSDR苹果叶片中的脂肪酸含量;利用尼罗红染色检测苹果叶片中的脂滴(LDs)积累情况。结果表明,瞬时表达MdSDR显著增强了苹果叶片对腐烂病菌(Valsa mali)的抗病性,试验组叶片病斑直径相比对照组减小约14.46%(P<0.001);瞬时表达MdSDR后苹果叶片中脂肪酸生物合成相关基因的表达显著上调(P<0.001),其中MdACCase上调48.41倍,MdKAR上调129.79倍,MdENR上调168.20倍,MdHAD上调8.67倍,MdβCT、MdKASⅠ和MdKASⅡ均上调约5倍;然而过表达MdSDR后苹果叶片中脂肪酸的积累水平无显著变化(P>0.05);进一步研究发现,过表达MdSDR后苹果叶片中调控脂滴合成的基因MdSEIPIN显著上调表达(P<0.05),脂滴数量大量增加。本研究初步证明MdSDR能够通过促进脂肪酸的合成,间接提高脂滴的数量,从而提高苹果的抗病性,为苹果抗性品种的研究提供了一定的理论基础。     

Interpretation of Leaf Analysis Performed in Early Vegetation in Apple Orchards

Mid-summer leaf analyses are commonly used as the standard method worldwide to assess the nutritional status of fruit trees. It may be too late to correct nutritional disorders by mid-summer. In this study, reference values that will be used to evaluate the nutritional status of apple trees early in the growing season were derived. To determine the reference values for all sampling periods, the regression curves were created by using the reference values of each period. Correlations were examined between the sixth period and earlier sampling times. The presence of statistically significant correlation coefficients was interpreted as leaf analysis can be used to determine the nutritional status of apples in the early season. It was concluded that leaf analysis can be carried out anytime from commencing two weeks after full loom to lasting 98 days after full bloom for all elements except Iron and Cupper.     

平凉市苹果叶部病害绿色防控技术规程

叶部病害是危害苹果生产的重要因素,科学防控可确保苹果产量和品质。为统一苹果叶部病害绿色防控技术标准,根据取得的最新研究成果并结合生产实践经验,从范围、规范性引用文件、术语和定义、防控原则、防控策略及防控措施等方面制定出了平凉市苹果叶部病害绿色防控技术规程,以期为平凉市苹果叶部病害的综合防控提供技术支持。     

重金属和生物有机肥对苹果根区土壤微生物的影响

通过土壤追施Cd ,Cu和生物有机肥,研究了重金属对红富士苹果根区微生物的危害以及生物有机肥减轻重金属对土壤微生物危害的效应。结果表明:施用生物有机肥后,果园根区土壤细菌、真菌和放线菌数量显著增加,细菌占绝对优势;土壤Cd浓度在10 30mg/kg范围内,随Cd浓度的增加,细菌数量大幅度减少;Cu元素对土壤微生物的危害情况与Cd相似,但程度比Cd轻;从生物有机肥中提取的有机质对Cd和Cu有明显的吸附作用,在pH值6～8的范围内,吸附率随pH升高而提高;在中性微酸的条件下(最适宜苹果栽培的土壤酸碱条件) ,有机质对Cu2 吸附率远高于对Cd2 的吸附率;生物有机肥明显减轻Cd ,Cu对土壤微生物的危害,并且对Cu污染土壤的改善效果更好     

Potassium Supply Influences Molybdenum,Nitrate, and Nitrate Reductase Activity in Eggplant

Abstract

Greenhouse experiments were conducted for two years (1993–1994) with eggplants to study the impact of potassium (K) as K₂SO₄ (0.5 mM, 1 mM, 2 mM, and 3 mM) on molybdenum (Mo) distribution and on aspects of nitrate (NO₃ ^?) metabolism, and fruit quality. The nitrates and Mo in leaf blades, petioles, and fruits as well as foliar in vivo nitrate reductase (NR; E.C. 1.6.6.1) activity were analyzed. In view of these results, the K application at levels exceeding 0.5 mM K, altered the NO₃ ^? and Mo status and distribution in the aboveground organs of eggplant. The 3 mM K distributed the NO₃ ^? proportionally between leaf blades, petioles, and fruits. The 0.5 mM K and the 1 mM K increased the NO₃ ^? and Mo concentration in fruits, respectively. These results indicated the 3 mM K the most appropriate treatment for the greenhouse eggplant production under Mediterranean climate conditions, with reduced NO₃ ^? density in fruits for human consumption.     

Sampling of Sugarcane Leaves in Field Experiments to Determine the Activity of Nitrate Reductase

Nitrogen (N) assimilation depends on nitrate reductase activity (NRA). Leaf sampling methods in field experimentation with sugarcane and analytical procedures are essential for the determination of the maximum activity (MA) of the enzyme. Thus, in five tests, it was possible to determine which period of the crop cycle should be used for leaf collection, the most adequate leaf for collection, the ideal number of leaves to be collected, the period of the day in which the enzyme has MA and which analytical procedures can be optimized. The evaluation of NRA in sugarcane should occur between 95 and 100 days after planting (DAP) and can be performed in any green leaf. In field experiments, it is recommended the collection of 15 leaves, which must occur between 12:00 and 12:30 h, with later incubation of the leaf tissues for 430 min, without vacuum application.     

Rapid Analysis of Apple Leaf Nitrogen using Near Infrared Spectroscopy and Multiple Linear Regression

A quick method was developed for diagnosis of nitrogen (N) in apple trees based on multiple linear regressions to establish the relationship between near-infrared reflectance spectra (NIRS) and the N contents of fresh and dry tissue. Spectral pretreatment methods such as derivatives, smoothing, and normalization were used. The derivatives appeared to be the most effective. The best calibration for fresh leaf gave 0.842 for the correlation coefficient of validation (R_v), 1.119 g kg^?1 for the root mean square error of prediction (RMSEP), and 8.311 for the ratio of the range in reference data from the validation samples to the root mean square error of prediction (RER). The best calibration for dried ground samples was obtained with R_v = 0.952, RMSEP = 0.633 g kg^?1, the ratio performance deviation (RPD) = 3.27, and RER = 13.728. The results showed that calibrations of dry-apple leaf are robust enough for an accurate prediction of N.     

肥料袋控缓释对苹果新根生长和氮素吸收的影响

为从苹果新根生长、发育角度探讨肥料袋控缓释施肥提高氮素利用率的机理,本试验以5年生苹果为试验材料,采用微根管技术对苹果新根生长动态进行连续3年的观测,同时利用¹⁵N同位素示踪技术研究肥料袋控缓释处理对苹果氮素吸收的影响。结果表明,肥料袋控缓释处理土壤的NH₄⁺-N和NO₃^--N浓度维持在12.46 mg·kg^-1以上,变异系数小于27.4%。肥料袋控缓释处理苹果新根发生数量比肥料撒施处理提高了34.2%。肥料袋控缓释处理苹果新根褐变时间为58 d,不施肥处理为34 d,撒施处理为41 d。肥料袋控缓释处理新根中值寿命为224 d,不施肥处理为142 d,撒施处理为182 d。肥料袋控缓释处理新根现存量显著高于撒施处理和不施肥处理,新根年周转率显著低于撒施处理和不施肥处理。8月底苹果根系活力以肥料袋控缓释处理最高(82.54 mg·g^-1·h^-1),显著高于撒施处理和不施肥处理。肥料袋控缓释施肥处理来自肥料的氮占总...     

外源水稻根系和茎叶碳氮在稻田土壤中释放的特征

东北地区气候寒冷,稻田土壤休耕期长,多处于冻结状态;水稻生长期短,土壤温度高且季节性淹水.外源水稻秸秆碳氮在东北地区稻田土壤休耕期和水稻生长期不同水热条件下的释放特征尚不完全清楚.通过室外培养试验方法,利用双标记(13C和15N)水稻根系和茎叶示踪技术和稳定同位素质谱分析技术,研究水稻根系和茎叶在稻田土壤中的腐解率、有...     

垂直孔施有机物对土壤硝酸盐代谢及苹果叶片光合作用的影响

土壤钻孔可改善通气性,施用有机物能增加土壤有机质,将两者相结合,以4年生红富士苹果为试验材料,在根区钻出垂直通气孔后,分别施入玉米秸秆、果树枝、生物炭和发酵果木屑,调查土壤硝酸盐代谢、苹果叶片光合与蒸腾、水分利用效率(WUE)及植株生长量等。结果表明:土壤垂直孔施玉米秸秆或发酵果木屑显著提高土壤硝化—反硝化强度及土壤硝酸还原酶(NR)和亚硝酸还原酶(NiR)活性;垂直孔施玉米秸秆、果树枝或生物炭显著提高叶片净光合速率、蒸腾速率和WUE;垂直孔施上述四种有机物料均显著提高40cm土层土壤的相对含水量,促进新梢加粗和伸长,其中,玉米秸秆的综合效果最显著,它在施用第10个月使土壤硝化强度、反硝化强度、叶片净光合速率和WUE分别提高52.68%、45.81%、57.32%和29.12%。     

腐殖酸对池塘底泥中铅、镉的离子形态分布及其活性的影响

本文探讨了腐殖酸对池塘底泥中铅、镉的离子形态分布及其活性的影响。结果表明,富里酸(FA)能使底泥中铅、镉的碳酸盐结合态、铁锰氧化物结合态和残渣态的含量下降,而有机结合态和可溶态的含量升高,但是胡敏酸(HA)则使其它各形态均向有机结合态转化。随着FA浓度的提高底泥中铅、镉的可溶态含量也呈增高的趋势,但是HA的作用与此相反,这就表明FA能活化底泥中的铅、镉,而HA则起到了钝化作用,且它们的作用随着浓度的增大而增大。另外,无论是FA还是HA它们对底泥中铅、镉的离子形态分布及其活性的影响均表现出对铅的作用大于对镉的作用。     

水稻不同生育期对硒吸收累积及铁膜的吸附特性

采用盆栽试验方法,研究不同生育期水稻各部位对硒的吸收累积及根表铁膜对水稻吸收积累硒的影响机制。结果表明:水稻营养器官生物量在拔节期积累最快,不同时期营养器官中硒含量不同,根中的硒在拔节期达到最大,根和茎中的硒在灌浆期和成熟期被转运至其他部位。水稻各组织中约50%的硒在拔节期和孕穗期被吸收,小穗吸收总硒的47.22%且是在孕穗期完成的,说明这两个时期对于水稻硒吸收累积非常关键。铁膜中硒占总硒的比例在幼苗期高达73.63%,是同时期茎中硒所占比例的4.87倍。随着生育期的推进,铁膜中硒所占比例显著递减,在成熟期降低至20.02%,同时期茎中硒占总硒的比例为65.42%。这表明,根表铁膜在水稻整个生长周期内通过吸附作用使其表面能够富集一定量的硒,在水稻生育后期,当土壤溶液中硒含量较少时,根表铁膜可能会作为一个硒源,吸附在根表铁膜中的硒重新被水稻所利用,铁膜在水稻硒吸收转运的过程中扮演了"缓冲器"的角色。明确不同生育期根表铁膜对水稻硒累积特性,在生产管理中可在不同生育期采取措施提高稻田硒生物有效性,从而为进一步提高农产品中硒含量提供科学依据。