Distribution of Glutathione in Osborne Fractions as Affected by Additions of Ascorbic Acid,Reduced and Oxidised Glutathione

Kernels of the wheat class DNS were stored for 21 months at 20°C. Flours were milled before (I) and after storage (II). Doughs from II were firmer than those from I, possibly due to the decrease of reduced glutathione (GSH) from 124 to 30 nmol/g. The two flours, as well as doughs that were prepared by the addition of GSH, oxidised glutathione (GSSG) and ascorbic acid (AA), were fractionated into albumin, globulin, gliadin, and acid-extractable and acid unextractable glutenin. During kneading of flour-water doughs, endogenous GSH was preferentially bound to the acid-extractable glutenin leading to an increase of protein-glutathione mixed disulphide (PSSG). Whereas addition of GSH to a dough enhanced the amount of PSSG in the acid-unextractable glutenin. GSSG increased the extensibility of the doughs but to a lesser extent than GSH and was mainly bound to the acid-extractable glutenin, most likely by an SS/SH interchange reaction with the SH groups of the proteins. GSH and GSSG, both in the presence of AA, also became bound into the glutenin but without an impairment of the improver action of AA on dough rheology. It is discussed that the addition of AA leads to a rapid conversion of GSH into GSSG, which then becomes attached to the glutenin. The increase of total non-peptide bound cysteine (PSSC) in the acid-extractable glutenin, which was favoured by AA, can be explained by a reaction of endogenous cystine with protein SH groups.     

外源抗坏血酸对镉毒害小麦幼苗的缓解作用

为了解抗坏血酸(AsA)对Cd2+毒害小麦幼苗生长的缓解作用,以小麦品种周麦27为材料,采用室内水培法分析了在Cd2+胁迫下小麦幼苗经不同浓度AsA处理后的生长及生理变化。结果表明,外源AsA能显著提高Cd2+胁迫下小麦幼苗的株高、根长、地上部干重、根系干重、根系活力、光合色素含量、渗透调节物质含量、抗氧化酶活性及叶片净光合速率、气孔导度和蒸腾速率,显著降低丙二醛含量和相对电导率以及叶片胞间CO2浓度。说明Cd2+胁迫下外源AsA可以通过提高小麦幼苗渗透调节物质含量及抗氧化酶活性来清除活性氧自由基,减少其对光合色素蛋白大分子的攻击作用,降低膜脂过氧化伤害程度,维持光合作用和细胞膜的稳定性,从而缓解了Cd2+对幼苗生长的毒害作用,其中以35mg·L-1 AsA的缓解效果最好。     

Foaming Properties of White Wheat Flour-Yoghurt Mixture as Affected by Fermentation

Effect of fermentation on the foam stability (FS) and overrun (O) of a white wheat flour-yoghurt mixture was investigated using response surface methodology with concentration (0·5–1·5%, w/v) and whipping time (30–120 s) being the independent variables. Regression equations for predicting the FS and O were developed. Results suggest that concentration had the most pronounced effect on the overrun while concentration and whipping time were both effective on foam stability. Response surface plots suggest that fermentation causes a decrease in the overrun, possibly resulting from the change in the structure of protein due to breaking down of molecules into small nitrogenous molecules as a result of fermentation. Fermented sample has a better foam stability (i.e8·0±0·1 min) than unfermented control sample (i.e5·0±0·1 min) at the same concentration and whipping time.     

Continuous Spectrophotometric Assay and Properties of Ascorbic Acid Oxidising Factors in Wheat

A continuous spectrophotometric assay was developed to measure ascorbic acid oxidation in crude Na₂SO₄ extracts of flour. The rate of ascorbic acid oxidation in flour extracts measured using this method was similar to the rate in flour-water suspensions and 2–4 fold less than the rate in dough measured using an indophenol-xylene extraction method. Flour extracts appeared to contain two ascorbic acid oxidising factors; one with optimal activity at pH 6·3 and 30 °C and the other with optimal activity at pH 10 and 40 °C. The pH 6·3 factor had properties similar to those of ascorbate oxidase (EC 1·10·3·3) in its pH and temperature stability, strong inhibition by NaN₃, KCN and diethyldithiocarbamate, inactivation by proteases, and greater stereospecificity towards -ascorbic acid than -isoascorbic acid. The pH 6·3 factor was most concentrated in the pollard milling fraction of wheat and was lowest in flour. The pH 10 factor had several properties indicating non-enzymic oxidation of ascorbic acid; it was not inactivated by proteases, it was inhibited poorly or not at all by the above ascorbate oxidase inhibitors, and it had low specificity for stereoisomers of ascorbic acid.     

抗坏血酸对盐胁迫下小麦幼苗生长抑制的缓解效应

为探明抗坏血酸(AsA)对盐胁迫下小麦幼苗生长的调控作用,采用室内水培法研究了不同浓度AsA处理对0.1 mmol·L-1 NaCl胁迫下2个小麦品种(周麦9号和周麦23号)幼苗生长的影响.结果表明,外施AsA极显著提高了盐胁迫下小麦幼苗的根长、芽长,幼苗叶片的Pro和可溶性蛋白含量以及根系活力显著升高,细胞膜透性及膜脂过氧化产物MDA含量显著降低.2个小麦品种对AsA处理的敏感程度存在差异,ASA对周麦23号的缓解效果相对较好.本实验中以1.5 mmol·L-1外源AsA缓解效果最好.     

施磷量对弱筋小麦扬麦9号籽粒淀粉合成和积累特性的调控效应

以弱筋小麦扬麦9号为材料,在缺磷土壤（速效磷含量4．1mg／kg）上进行施磷量试验,研究施磷量对小麦籽粒淀粉合成、积累及相关酶活性的影响。结果表明。在施磷（P2O5）0～108kg／ha范围内,增加施磷量,籽粒直链淀粉、支链淀粉、总淀粉积累量、积累速率上升,旗叶蔗糖磷酸合成酶（SPS）活性和蔗糖含量提高,籽粒蔗糖合成酶（SS）活性增强。籽粒蔗糖含量提高。籽粒ADPG焦磷酸化酶（AGPP）、可溶性淀粉合成酶（ssS）、束缚态淀粉舍成酶（GBSS）活性提高,成熟籽粒直链淀粉、支链淀粉、总淀粉含量下降。施磷量超过108kg／ha后,直链淀粉、支链淀粉、总淀粉积累量、积累速率及蔗糖含量、SPS、SS、AGPP、SSS、GBSS酶活性呈下降趋势。     

Dielectric Relaxations of Frozen Wheat Doughs Containing Sucrose, NaCl, Ascorbic Acid and Their Mixtures

The effects of sucrose, NaCl, and ascorbic acid on dielectric relaxations of frozen wheat doughs were investigated using dielectric analysis (DEA). All ingredients were dissolved in distilled water used to prepare wheat flour doughs to optimum consistency using a 10 g bowl Micro-Mixer. DEA measurements were made at a heating rate of 1 °C/min from −150 to 10 °C. Before the measurements, samples were equilibrated at −30 °C for 15 min to allow maximum ice formation, and then cooled at 1 °C/min to −150 °C. The frequencies used were 0·1, 0·5, 1, 5, 10, 20, 50, 100 and 1000 Hz. The dissipation factor (tan δ) of DEA showed an α-relaxation (glass transition), two low temperature relaxations (β and γ) and ice dissolution. Added NaCl had a markedly depressed the glass transition temperature (T_g′) and onset of melting of ice temperature (T_m′), probably because of the higher conductivity of the frozen material, and the decreased transition temperatures of the unfrozen solute phase. At the higher frequencies, the α-relaxation coincided with melting of ice, and all relaxation temperatures (α, β and γ) increased with increasing frequencies.     

Spatial Variability Patterns of Wheat Growth and Soil Properties in a Small Field as Affected by Tillage Intensity

Abstract

The objective of this study was to obtain information about spatial heterogeneity as a basis for site-specific soil and crop management in small fields. The spatial variability patterns of wheat growth parameters and soil properties, e.g. nitrate, available phosphate, pH, and soil surface hardness, were investigated on a 0.25 ha field of Humic Andosol in 1998 - 1999. Two plots in the field had been tilled with different intensities since autumn 1997. A plot was minimum-tilled with a rotary tiller (MT) and the other plot was conventionally tilled with a moldboard plow and disc-harrowed (CT). Raw data, collected from 100 locations with 2.5 m×5 m spacing in each plot, were divided into trends (large-scale deterministic structure) and residuals (small-scale stochastic structure) by median polishing. Trends were more dominant in CT than in MT. The trend of wheat above-ground biomass at harvest was similar to those of soil nitrate and available phosphate. These trends were partly due to high variability across rows, possibly caused by the same traffic direction of farming operations for several years. The residual data, on the other hand, showed no correlation among the parameters. The spatial dependency of the residual data for soil properties, except for pH, was not apparent for distances larger than the minimum sampling distance (2.5 m). It is concluded that modification of fertilizer application based on the trend data may improve the efficiency of fertilizer use while small-scale site-specific management based on the residual data may be practically difficult. Key words :     

Gas Cell Stabilisation and Gas Retention in Wheat Bread Dough

Gas cell stabilisation and gas retention are of considerable interest because of their technological significance in bread making. We review recent studies in relation to the stabilisation of gas cells and the mechanisms of gas retention, and discuss how these may be affected by the liquid phase of dough. The possibility is discussed of the involvement of surface active materials, such as proteins and pentosans dissolved in the dough aqueous phase, and, perhaps more importantly, non-starch polar lipids in the formation and stabilisation of gas cells. There is accumulating evidence for the hypothesis that liquid films play a critical role in the mechanisms of gas retention in dough. The hypothesis proposes that two closely related, consecutive stages are involved in dough expansion. During the first stage, the expanding gas cells remain discrete until discontinuities develop in the starch–protein matrix, leaving areas containing only a liquid film. The timing and the degree to which such discontinuities occur is largely dependent on gluten proteins. The second stage involves an increase in the surface area of the liquid film as discontinuities become increasingly frequent during expansion. Failure of the lamellar film to maintain the rate at which new surface area is generated leads to the rupture of this film and, consequently, the loss of gas retention. Consideration is also given to the role of bakery fat in gas retention and to additional factors that affect gas retention in wholemeal doughs, in particular the physical disruption of the foam structure of such doughs by components of the outer layers of the grain.     

利用抗坏血酸揭示小粒黑豆对胞囊线虫抗性的研究

以抗感大豆胞囊线虫3号生理小种的小粒黑豆(ZDD1412)和辽豆10为试材,温室盆栽条件下人工接种大豆胞囊线虫,以未接种作对照,接种后7、14、21、28和35 d取样,测定大豆根内抗坏血酸含量和抗坏血酸过氧化物酶(APX)活性的动态变化以及不同浓度抗坏血酸对大豆胞囊线虫胞囊孵化和二龄幼虫抑制率的影响.结果表明:抗病品...     

Wheat Yield and Water Use as Affected by Micro-Basins and Weed Control on the Sloping Lands of Morocco

Summary

Traditionally in Morocco the wooden plow was the most widely used implement for soil tillage, especially on sloping lands. Mechanization was introduced on flat areas and was extended more and more toward sloping lands, so the tillage accentuated the problems of water runoff and soil erosion. The objective of this study was to determine the effect of micro-basins on runoff, water storage by increasing infiltration, and wheat yield. In addition, the interaction with weeding was tested to reduce water losses by evapotranspiration from weeds. Four treatments were used, as follows: BW (micro-basins, weeded), NBW (no micro-basins, weeded), BNW (micro-basins, not weeded) and NBNW (no micro-basins, not weeded). Field experiments were carried out during three years using a split plot design with four replications: two at Meknès in 1990-91 and 1991-92 and a third at Khémisset (1992-93). Slopes were 2.5% for Meknès and 3.5% for Khémisset. Rainfall received was 523.3, 483.7, and 473.0 mm, respectively, for the 1990-91, 1991-92, and 1993-94 growing seasons.

The results showed that the effect of micro-basins in interaction with weeding was statistically significant in 1990-91 and 1993-94 for soil water storage, grain yield, spikes/m², kernels/m², thousand kernel weight, and water use efficiency. In 1991-92, yield increases were not significant, because of a drought that lasted almost two months after emergence. We conclude that these technical management practices are especially important in rainy years when rainfall intensities are high and cause water runoff.     

Relationship Between Gliadin Alleles and Dough Strength in Italian Bread Wheat Cultivars

Dough strength, as determined by Alveograph W, was studied in Italian bread wheat cultivars grown at several locations over 21 years of testing. Broad sense heritability of Alveograph W was found to range between 0·40 and 0·82, variation in this parameter being affected by genotype×year interactions. Standardised Alveograph W values (Wst) across 40 environments (location–year combinations) were computed for 54 cultivars with reference to the long-term control (cv. Mec), and a quality score based on the Wst value was given to each gliadin allele occurring in at least four of the 54 cultivars analysed. Significant differences in Wst values were observed at theGli-B1,Gli-B2andGli-A2loci. AllelesGli-B1b,Gli-B2candGli-A2bwere significantly related to high gluten strength. An overall quality score based on allelic composition at these loci explained 41% of the observed Wst variation in the 54 cultivars used for the score definition, and 23% to 48% of W value variation in three sets of independent data. The combination of this score with a quality score based onGlu-1alleles coding for highM_rglutenin subunits could explain, on average, about 50% of gluten strength variation.     

硅肥对干旱胁迫下冬小麦旗叶抗坏血酸-谷胱甘肽循环系统及产量的影响

为从抗坏血酸-谷胱甘肽循环的抗氧化角度提示硅元素的抗旱机理,以冬小麦品种豫麦49-198为材料,研究了硅肥对不同干旱胁迫（对照、轻度胁迫、重度胁迫）下小麦旗叶抗坏血酸-谷胱甘肽循环系统中关键基因表达、抗氧化物质含量及产量的影响。结果发现, 在轻度和重度胁迫持续10 d时,施用硅肥与不施用硅肥比较,小麦旗叶抗坏血酸分别提高了16.57%和8.39%,小麦旗叶中抗坏血酸-谷胱甘肽循环系统关键酶基因TaAPX、TaGR、TaGS相对表达量分别提高了60.23%、73.61%、11.35%和87.97%、25.70%、114.64%;在轻度胁迫和重度胁迫持续20 d时,施用硅肥与不施用硅肥比较,小麦旗叶抗坏血酸含量分别提高了18.03%和6.81%,小麦旗叶中抗坏血酸-谷胱甘肽循环系统关键酶基因TaAPX、TaGR、TaGS相对表达量分别提高了124.54%、44.42%、56.80%和118.19%、41.42%、269.21%;小麦籽粒产量分别提高了29.23%和33.31%。以上结果说明,施用硅肥可以增强小麦旗叶抗坏血酸-谷胱甘肽循环系统功能,提高小麦植株的抗旱性,增加籽粒产量。     

农田土壤Nmin对马铃薯块茎形成的影响

为明确农田土壤矿质氮(Nmin)含量对马铃薯块茎形成的影响,在内蒙古阴山北麓马铃薯主产区大田条件下,利用主栽马铃薯品种‘克新1号’,通过设置不同供氮水平,研究了薯田土壤Nmin含量对块茎形成的时间、数量以及重量的影响。结果表明:土壤Nmin含量在18⁵0 mg/kg范围内时均可形成块茎,且在18.6450 mg/kg范围内时均可形成块茎,且在18.64¹9.94 mg/kg可较早形成块茎,超过50.57 mg/kg时,不形成块茎;较高的土壤Nmin含量会降低块茎形成的数量,在内蒙古阴山北麓地区,马铃薯出苗39 d以后,块茎数量不再增加;虽土壤Nmin含量的增加推迟了块茎的形成时间,但较高的土壤Nmin有利于马铃薯生育后期单株块茎重量的增加。     

Overexpression of a Gluten Protein in Transgenic Wheat Results in Greatly Increased Dough Strength

The transgenic wheat line B73-6-1 contains additional genes encoding a gluten protein called HMW subunit 1Dx5, resulting in a four-fold increase in the proportion of this component in the seed proteins and corresponding increases in the proportions of total HMW subunits and total glutenins. This is associated with a dramatic increase in dough strength, as measured using a small scale Mixograph, with dough produced from B73-6-1 being too strong to be used in conventional breadmaking.     

铁观音鲜叶茶多酚含量与气象因子的相关性研究

为探明影响铁观音鲜叶茶多酚含量的关键气象因子,本研究收集安溪主要产茶乡镇的铁观音秋季首轮新梢生长期（45 d）内的总降水量、日均温、有效积温、最高气温、最低气温、平均相对湿度及10 cm地温,分析其对铁观音鲜叶茶多酚含量的影响。皮尔森相关分析、主成分分析与偏最小二乘回归分析表明影响安溪县不同产地秋季铁观音鲜叶茶多酚含量的关键气象因子为45 d总降水、最高气温以及平均相对湿度,其中总降水与最高气温与鲜叶茶多酚含量呈显著正相关,平均相对湿度与鲜叶茶多酚含量呈负相关。     

Phytic Acid Level in Wheat Flours

The phytic acid content of refined (hand-made and factory-made) and whole (factory-made) wheat flours, much consumed in the Canary Islands, have been determined in this study. A total of 200 samples of flours from different types (100 refined and 100 whole) were analysed. The method proposed by Garcı́a-Villanova et al. (1982) was used for determination of phytic acid content in wheat flours. Most of the phytic acid concentrations are within the range 2–4 mg/g for the refined flours and 6–10 mg/g for the whole ones. The arithmetic mean obtained from all the samples studied is 3·77 mg/g for hand-made, refined flours, 2·96 mg/g for factory-made refined flours and 8·50 mg/g for the whole ones. On analysing the phytic acid content in all the flour samples, significant differences were observed for the different types of flour. Refined flours had a content lower than whole ones.     

UV-A辐射对大豆芽苗菜中抗坏血酸含量的影响

以黑暗培养为对照,以白光、红光、蓝光、黄光、UV-A和UV-B为处理,研究了不同光质对大豆芽苗菜生长和抗坏血酸含量的影响。结果表明:与对照相比,光照处理显著降低了大豆芽苗菜下胚轴的长度(白光除外),且显著提高了下胚轴和子叶中抗坏血酸含量。与其它光质处理相比,UV-A连续光照36 h后,下胚轴和子叶中抗坏血酸含量提高最显著。进一步着重研究了UV-A的调节机理,与对照相比,UV-A连续光照36 h后,大豆芽苗菜子叶中谷胱甘肽含量显著升高,下胚轴和子叶中DHAR、GR酶活性及其基因的相对表达量均显著提高。综上所述,光照有利于大豆芽苗菜中抗坏血酸含量的积累;UV-A可能是通过提高DHAR、GR酶活性及基因的表达量显著提高抗坏血酸的含量。     

Wheat Straw Modified with Palmitic Acid as an Efficient Oil Spill Adsorbent

Raw wheat straw was modified to obtain a new oil absorption material, using palmitic acid as the esterifying agent in dimethyl sulfoxide (DMSO) without additional catalysts. The oil absorbency of the esterified wheat straw material towards 0^# diesel reached 24.31 g/g under the following optimum reaction conditions: pretreated wheat straw: palmitic acid weight ratio of 1:10, reaction temperature of 90 °C, and reaction time of 3 h. The chemical composition and structure of wheat straw fiber before and after esterification reaction were compared using Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM) methods. The results indicate that the esterification reaction was carried out smoothly, and the wheat straw afterwards had lower crystallinity and a rougher surface with more irregular folds. Additionally, the oil sorption capacity, selectivity, and absorption kinetics of the esterified wheat straw were also investigated. The esterified wheat straw showed good potential for converting agricultural residues into efficient cellulosic oil sorbents.     

外源抗坏血酸对铝毒害大麦幼苗的缓解效应

为了明确抗坏血酸对作物铝毒害的作用,采用营养液培养试验研究了叶面喷施不同浓度抗坏血酸(AsA)对2个耐铝能力差异较大的大麦品种幼苗铝毒害的缓解效应。结果表明,与单独铝处理相比,喷施0.01、0.05和0.25mmol·L-1 AsA对铝胁迫大麦幼苗均有较好的缓解作用,大麦幼苗株高、生物量和叶绿素含量等均提高,功能叶丙二醛(MDA)和可溶性糖含量、超氧化物歧化酶(SOD)和过氧化物酶(POD)活性等均显著低于单独铝处理。但0.5mmol·L-1 AsA喷施后缓解效应下降,植株生物量等下降,MDA含量等上升。表明适宜浓度的外源AsA可有效缓解铝毒害引发的大麦生长抑制和氧化胁迫,但浓度过高则产生氧化作用,铝敏感基因型反应更强烈。本试验中以0.25mmol·L-1的AsA缓解效果最佳。