外源蔗糖对小麦幼苗耐盐性的影响

本研究选取小麦品种"沧6001"(抗盐性品种)和"石4185"(盐敏感品种)为试验材料,采用水培方法,对加入蔗糖后两个小麦品种的耐盐性进行比较。结果表明,盐胁迫下,"沧6001"和"石4185"小麦根系生长均受到抑制,"石4185"根系受到抑制的程度大于"沧6001";蔗糖预处理可以显著缓解盐胁迫对根系生长的抑制作用。蔗糖预处理12 h后,"沧6001"和"石4185"的可溶性糖含量上升,与"石4185"相比,"沧6001"具有更高的可溶性糖水平,但是蔗糖预处理后"石4185"可溶性糖含量的增加量高于"沧6001"。H2DCFDA荧光探针检测和PI荧光染色检测结果表明,蔗糖预处理可有效降低盐胁迫下小麦幼苗体内活性氧累积水平,保护细胞膜的完整性并减小根尖细胞死亡率。蔗糖预处理可以提高小麦幼苗SOD和APX(P<0.05)、CAT活性(P>0.05)。本研究对于理解外源物质对小麦耐盐性影响的生理机制及筛选耐盐性的小麦品种具有指导意义。     

鲜食玉米剥皮机的设计与试验

为了解决中国在鲜食玉米加工中的剥皮难题,在借鉴国外先进鲜食玉米剥皮技术的基础上研制出一种鲜食玉米剥皮机。该机采用一对转辊相向转动,转辊与玉米穗苞叶接触产生摩擦将玉米苞叶先搓起一角,之后一对转辊夹住苞叶旋转将其剥掉。该设备可适应玉米籽粒含水率介于58%～73%间的原料,对脆嫩易剥的鲜食玉米籽粒品种的破损率≤5%、剥净率≥90%、剥皮质量好。解决了中国鲜食玉米剥皮技术存在的剥净率偏低、破损率等主要性能指标不能满足使用要求的难题。经过对该设备试制、试验结果表明,完全适合高水分鲜食玉米穗剥皮。     

季节性干旱条件下氮肥与密度运筹对鲜食糯玉米产量的影响

为探讨季节性干旱下糯玉米的高产栽培模式,本试验研究了氮肥和密度运筹下糯玉米的产量与氮肥农学利用率.结果表明,在9至11月的干旱条件下,随着密度和施氮量的增加,鲜果穗产量逐渐增加,在氮肥用量(225 kg/hm2)和6万株/hm2处理下玉米鲜果穗产量最高,比不施氮处理提高了32.29％.氮农学效率表现较高的为中施氮量(175 kg/hm2)、中密度(5.25万株/hm2)和中施氮量(175 kg/hm2)、高密度(6万株/hm2)处理,分别为10.57 kg/kg和11.79 kg/kg,表现最低的为高施氮量(275 kg/hm2)、低密度(4.5万株/hm2),为3.76 kg/kg.因此,在南方红壤地区,通过合理搭配氮肥量和种植密度,可以在季节性干旱下实现鲜食糯玉米的高产.     

氮素水平对单作和间套作小麦玉米品质影响的比较研究

以间套作小麦玉米、单作小麦和单作玉米为研究对象 ,研究了在间套作和单作条件下氮素水平对小麦、玉米品质的影响。结果表明 ,间套作小麦和单作小麦相比具有明显的间套作品质优势 ,且间套作小麦表现出明显的边行品质优势。在相同施氮水平下 ,间套作小麦的蛋白质含量、沉淀值、干、湿面筋含量等品质指标均明显高于单作小麦 ,施氮水平显著改善单作和间套作小麦的品质指标 ;而间套作玉米和单作玉米相比则表现出明显的间套作品质劣势 ,在相同施氮水平下 ,间套作玉米的蛋白质含量、脂肪含量、百粒重等品质指标明显低于单作玉米 ,施氮水平显著改善间套作玉米的蛋白质含量、脂肪含量、百粒重等品质指标。     

小麦、玉米施用微生物接种剂增产效应初报

施用微生物接种剂、化肥或化肥与微生物接种剂配施均能促进小麦、玉米的个体发育 ,提高净光合强度 ,通过提高穗粒数和千粒重来提高产量 ,以化肥与微生物接种剂配合施用的处理效果最显著 ,与对照相比 ,小麦增产 33.9% ,玉米增产 2 7.3% ;这说明适当降低化肥用量并配合施用生物肥料 (拌种或追施 ) ,可以在不增加 (甚至减少 )肥料投入的情况下提高小麦、玉米的产量 ,提高经济效益     

Effect of sucrose ester addition on nucleation and growth behavior of milk fat-sunflower oil blends

The effects of addition of the sucrose esters (SE) P-1670, P-170, and S-170 to a high-melting fraction of milk fat (HMF) and its blends with sunflower oil (SFO) on nucleation and growth were studied by laser polarized light turbidimetry and polarized light microscopy (PLM). The three SE delayed nucleation of HMF at the temperatures selected. P-1670 did not modify average crystal size after 3 h at crystallization temperature (T(c)) or crystal size distribution and modified crystallization kinetics only slightly. P-170 and S-170, however, markedly diminished crystal size and narrowed crystal size distribution. Activation free energies of nucleation at equivalent supercooling, calculated using the Fisher-Turnbull equation, significantly increased with addition of SE. According to these results, among the mechanisms described in the literature for fats or emulsions, the cocrystallization hypothesis is the one that better described the effects of sucrose esters on crystallization behavior in these systems.     

再生水灌溉对冬小麦和夏玉米产量及品质的影响

食作物是利用再生水灌溉的主要农作物之一,产量和品质是决定其再生水灌溉可行性的重要因素,该文系统研究了再生水灌溉对典型粮食作物——冬小麦、夏玉米产量与品质的影响规律,为粮食作物再生水安全灌溉提供科技支撑。通过田间试验得出：再生水灌溉处理与清水处理相比,冬小麦和夏玉米平均增产6.49%和5.42%,再生水灌溉对冬小麦和夏玉米产量没有显著影响（α＝0.05）;再生水灌溉对冬小麦和夏玉米籽粒中的粗蛋白、可溶性总糖、粗灰分、粗淀粉和还原型Vc含量等主要品质指标无显著性影响（α＝0.05）;再生水灌溉处理的冬小麦籽粒中全氮质量分数平均增加10.2%、夏玉米籽粒中全氮、全磷质量分数平均增加10.40%和16.40%,冬小麦籽粒中全磷、全钾含量和夏玉米籽粒中的全钾含量没有明显变化。该研究成果对于推动再生水灌溉利用具有积极意义。     

Radioimmunoassay of deoxynivalenol in wheat and corn

With the availability of antibody against deoxynivalenol triacetate (DON-triacetate), a radioimmunoassay (RIA) for DON in wheat was developed. DON is extracted from the sample with acetonitrile-water (84 + 16), defatted with hexane, and then reacted with acetic anhydride to form DON-triacetate. The reaction mixture is loaded onto a C-18 cartridge to remove excess reagents and impurities. Acetylated DON is eluted from the cartridge with 50% methanol in water, and then analyzed by radioimmunoassay utilizing antiserum against DON-triacetate and tritiated DON-triacetate. Overall recovery for DON added to wheat between 50 and 5000 ppb was 86% with a standard deviation of 7% and coefficient of variation of 8%. The limit of detection for DON was about 20 ppb. Analysis of 12 naturally contaminated wheat, corn, and mixed feed samples for DON revealed that RIA results agreed well with thin layer chromatographic analyses performed by other laboratories.     

外源碳、氮处理对春小麦花后干物质积累及籽粒产量的影响

为探明小麦花后碳、氮代谢平衡对干物质积累和产量的影响,采用质量浓度2%的尿素和5%的蔗糖作为外源氮、碳调控物质,在强筋型龙麦33和中强筋型克旱19两种类型春小麦的抽穗期叶面喷施,分别于喷施后5、10、15、22、29和36 d取样,测定小麦植株不同部位器官的干重,并于成熟收获后取样测定产量构成。结果表明:小麦抽穗后旗叶的干物质积累逐渐增加,而倒二叶的干物质积累降低,但籽粒灌浆阶段,旗叶和倒二叶总的干重趋于稳定,进入籽粒成熟期后重量急剧降低;穗下节鞘、倒二节鞘的干物质积累呈单峰曲线,节鞘干物质积累量占地上部干物质积累的比例逐渐降低。外源氮处理缓解了旗叶干重损失,促进了穗下节鞘和倒二节鞘的干物质积累,而外源碳处理反之。外源碳、氮处理不同程度提高了穗轴单位长度干重,显著降低了无效小穗比率,提高了穗粒数和千粒重,尤其是外源氮处理作用显著,龙麦33和克旱19的无效小穗比率分别降低了3.3%、3.7%,穗粒数增加了19.7%、8.4%,千粒重分别增加了2.7、1.4 g,外源喷施蔗糖、尿素使龙麦33和克旱19的单产分别提高了6.9%、15.8%和10.1%、16.9%。因此,外源氮、碳处理通过增加旗叶干物质积累促进了穗轴单位长度干重,提高物质向穗部的输导能力,从而减少了无效小穗,提高了穗粒数和千粒重,增加了籽粒产量,尤其是氮处理作用显著。     

Effect of alpha-amylases from different sources on the retrogradation and recrystallization of concentrated wheat starch gels: relationship to bread staling

Concentrated starch gels were supplemented with four alpha-amylases from different sources. The retrogradation and recrystallization of the gels were evaluated using differential scanning calorimetry (DSC) and X-ray crystallography. Correlations between the retrogradation data and the carbohydrate fractions extracted from these gels were determined. The thermostable (TBA) and intermediate temperature stability (ISBA) bacterial alpha-amylases were most effective in decreasing the rate of retrogradation of the starch in the gels. The cereal alpha-amylase at the high level (CAH) was also effective. Supplementation with the alpha-amylases increased the crystallinity of the gels. Gels supplemented with TBA or ISBA were most crystalline and retrograded to a lesser extent. The results indicated that DSC gives not only a measure of recrystallized amylopectin but also a measure of total order (recrystallized amylopectin and double-helical content). The maltooligosaccharides produced by the enzymes did not appear to be responsible for the reduced rates of retrogradation, but they appeared to be an expression of the degree of starch modification that was responsible for the inhibition of retrogradation. The crystallinity and retrogradation data were similar to results reported for bread and strongly suggest that bread staling is caused by the retrogradation of starch. The results also indicate that alpha-amylases decrease the rate and extent of retrogradation of starch gels by inhibiting the formation of double helices.     

Factors affecting the collection and fitting of nuclear magnetic cross-relaxation spectroscopy data with application to waxy corn starch

An examination of the methods for nuclear magnetic cross-relaxation spectroscopy (CRS) data collection and analysis was conducted using water and an aqueous waxy corn starch suspension to better perform and interpret the results obtained using CRS. The CRS data collection properties evaluated were the time to achieve steady state saturation, the direct saturation of liquid protons, generation of transverse magnetization, and dependence of the offset frequency and radio frequency (RF) field strength of longitudinal relaxation in the presence of RF saturation. Effects were evaluated for variations of input values of RF saturation field strength, apparent cross-relaxation rate, and solid longitudinal relaxation rate on the results for solid content and solid internal mobility from fitting NMR data to modified theoretical expressions. Discrepancies between fitted and stoichiometric values for the solid to liquid proton ratio were investigated. The fitting procedure used a Gaussian line shape for RF saturation of the solid-like spin system and a Lorentzian line shape for RF saturation of the liquid-spin system. Conditions under which acceptable results can be obtained with limited data sets are discussed.     

Limited survey of deoxynivalenol in wheat and corn in the United States

A limited survey was conducted over a 2-year period to determine the incidence and levels of deoxynivalenol (DON) in corn and wheat grown in selected areas of the United States. Samples of corn (198) and wheat (247) were collected and analyzed by a gas chromatographic method. Sixty-six percent of the corn samples collected in 1984 and 30% of the corn samples collected in 1985 contained DON. The average concentration of DON in corn, by state, ranged from 0.11 to 1.20 micrograms/g; the maximum concentration was 2.47 micrograms/g. Only 2 of the 247 samples of wheat contained DON at a concentration greater than 2 micrograms/g, which is the level of concern suggested by the Food and Drug Administration for wheat entering the milling process for human consumption.     

Comparative study of the retrogradation of intermediate water content waxy maize, wheat, and potato starches

The retrogradation of extruded starches from three different botanical sources was studied in concentrated conditions (34 +/- 1% water) at 25 degrees C using differential scanning calorimetry (DSC) and isothermal calorimetry, Fourier transform infrared spectroscopy (FTIR), and wide-angle X-ray scattering. Potato starch showed the highest rate of retrogradation (approximately 0.17 h(-1)) followed by waxy maize (approximately 0.12 h(-1)), while the retrogradation of wheat starch was the slowest (approximately 0.05 h(-1)). In addition to the kinetics, the extent of molecular order in the retrograded samples was studied in detail in terms of "short-range" (helical) and "long-range" (crystalline) distance scales. The amylopectin crystallinity indices were essentially the same (approximately 47-51% amylopectin basis) for the three starches. However, significant differences were found in the enthalpy of melting measured by DSC after "full" retrogradation (potato, 11.6 +/- 0.7; waxy maize, 9.0 +/- 0.5; and wheat, 6.1 +/- 0.3 J/g of amylopectin). The degree of short-range molecular order in the retrograded state determined by FTIR was waxy maize > potato > wheat. The effect of amylopectin average chain length and the polymorphism of the crystalline phase were taken into account to explain the differences in the retrogradation enthalpies.     

秸秆还田与施氮对冬小麦生长发育及水肥利用率的影响

田间试验研究了小麦-玉米一年两熟耕作区玉米秸秆还田与氮肥配施和化肥单施对冬小麦生长发育、籽粒产量及氮肥表观利用率和水分利用效率的影响。结果表明, 施氮量相同时, 秸秆与氮肥配施越冬前和拔节期冬小麦总茎数和单株分蘖数低于化肥单施, 施氮量在75~225 kg·hm^-2 时, 植株干重高于化肥单施; 孕穗期到成熟期植株干重、成穗率和产量构成因素秸秆与氮肥配施处理高于化肥单施处理, 籽粒产量增加58.9~339.6kg·hm^-2, 水分生产率提高0.026~0.083 kg·m^-3。施氮量在75 kg·hm^-2 时, 秸秆与氮肥配施的氮肥表观利用率低于化肥单施; 在150~300 kg·hm^-2 时高于化肥单施。因此, 针对目前黄淮海麦区小麦-玉米一年两熟种植制度下, 秸秆还田前期生物争氮、后期供肥能力增强的特点, 秸秆连续还田后配施纯氮225 kg·hm^-2, 可有效提高灌水和氮肥利用率, 实现冬小麦高产高效栽培。     

Effect of starch on the molecular mobility of amorphous sucrose

Molecular mobility in amorphous solid biomaterials is modulated by the composition and environment (primarily temperature). Phosphorescence of the triplet probe erythrosin B was used to generate a mobility map within amorphous sucrose films doped with starch ranging from 0.001 to 0.1 g starch/g sucrose. Data on the emission energy and lifetime of erythrosin B in sucrose and sucrose-starch films over the temperature range from 5 to 100 °C indicates that starch influences the molecular mobility as well as dynamic site heterogeneity of amorphous sucrose in a dose-dependent manner. At a starch/sucrose weight (wt) ratio below 0.005, both emission energy and lifetime decreased, and both the dipolar relaxation rate and nonradiative quenching rate k(TS0) increased, indicating that starch increased the matrix molecular mobility. At a ratio above 0.005, both emission energy and lifetime increased, and the dipolar relaxation rate and nonradiative quenching rate decreased, indicating that starch decreased the matrix mobility both in the glass and in the melt. The mobility showed a minimum value at a ratio of 0.01. The interactions existing in the sucrose-starch matrix are considered as the determining factor to influence the molecular mobility of sucrose-starch mixtures. Changes in the distribution of emission energies (emission bandwidth) and lifetimes indicated that starch increased the spectral heterogeneity at high contents while showing insignificant change or a slight decrease in the heterogeneity at low starch contents. These data illustrate the complex effects of a polymer with mainly linear structure and flexible conformation on the mobility of an amorphous, hydrogen bonded sugar matrix.     

Amyloglucosidase hydrolysis of high-pressure and thermally gelatinized corn and wheat starches

The study of glucose production using amyloglucosidase as a biocatalyst was carried out using high-pressure and thermally gelatinized corn and wheat starches. For corn starch, the measured initial rate of glucose production obtained from thermal gelatinization is faster than that obtained from the two high-pressure treatments, but the equilibrium yield of glucose was found to be similar for the three treatments. High-pressure treatments of wheat starch significantly improve the equilibrium yield of glucose compared with those obtained from the thermally gelatinized wheat starch. This difference has been related to the formation of amylose-lipid complexes during heating and could also explain previous physicochemical differences observed between high-pressure and thermally gelatinized starch.     

华北地区小麦、玉米两季秸秆还田存在问题及对策研究

介绍了华北地区冬小麦—夏玉米轮作一年两熟中秸秆还田的方式、现状。采用实地调查、文献资料查阅和专家走访等研究方法,总结和分析了华北地区小麦、玉米秸秆直接还田存在的相对还田量大、秸秆粉碎质量差、秸秆与土壤混合不匀、麦田病虫害加重及还田机械部件磨损严重等问题。并提出了小麦秸秆全量还田、玉米秸秆还田与收集利用并重、夏玉米秸秆及时粉碎还田、土壤轮耕、麦田施尿素调节C/N、造墒播种防病治虫、政府补贴推动等措施。为华北地区小麦、玉米秸秆还田技术的机理研究和推广应用提供参考。     

不同基因型糯玉米氮素吸收利用效率的研究Ⅲ.氮素分配转移特性的基因型差异

为了解糯玉米氮素分配转移规律及其与氮索吸收利用的关系，揭示氮素分配转移的基因型差异及其对产量形成的作用，本文在同一氮素供应水平下研究了31个糯玉米品种的氮素分配转移特性。结果表明，糯玉米生育期间氮素的分配中心是随生长中心转移而变化的，开花前主要分配在叶片和茎秆中，开花后氮素的分配中心开始由茎、叶转向雌穗，并逐渐以子粒建成为中心。糯玉米不同品种各器官氮素转移率及其对收获产品的贡献率存在显著差异。相关分析表明，氮素转移率主要影响产量、氮素利用效率及氮收获指数的高低，而对氮素吸收总量的影响较小。通径分析表明，鲜穗高产品种茎秆的氮素转移率较高，鲜子粒高产品种茎秆和雄穗的氮素转移率较高，成熟子粒高产品种叶片、苞叶及穗轴的氮素转移率均较高；叶片的氮素转移率高有利于品种鲜穗、鲜子粒及成熟子粒氮素利用效率的提高。属于高产、氮素吸收量大、氮素利用效率高基因型的6个品种，其鲜食期和成熟期的氮素总转移率平均值分别为25．53％和47．60％，比其他品种分别高27．48％和22．94％；鲜食期和成熟期的子粒氮收获指数平均值分别为0．35和0．62，比其他品种分别高8．43％和9．90％。