Some significant functions of silicon to higher plants

Silicon may be regarded as an essential element to cereals plant from an agronomic viewpoint. It is implicated as a factor influencing the degree of susceptibility of cereals to fungal attack. Vegetation in the tropics contains much more silicon for the protection. Once the silicon dioxide has been taken up by plants, it is rapidly accumulated in insoluble form and remains in the tissues. Yield response over the control will not be obtained if available silicon exceeds 11 mg SiO₂/100 g in the soil. The addition of silicon to the culture solution, at the rate of 75 ppm Si, decreased the accumulation of Mn, Cu, Fe, Zn, N, P and transpiration rate, but increased Ca, Mg, Si and carbohydrate contents. It is concluded that addition of silicon is particularly effective when combined with a heavy rate of nitrogen and magnesium.     

Changes in the phenolic compound content and antioxidant activity in developmental maize kernels and expression profiles of phenolic biosynthesis-related genes

Phenolic compounds have various nutritional and functional properties, especially antioxidant activity. The objective of this study was to explore the relationship between the phenolic compound accumulation, antioxidant property and gene expression during maize kernel development. In this study, we explored the effects of developmental stage on the accumulation of phenolic compounds and their antioxidant activities. The expression levels of genes involved in phenolic biosynthesis were also studied. The results showed that the total phenolic content (TPC) and total anthocyanin content (TAC) were gradually increased from 15 to 48 days after pollination (DAP), whereas the total flavonoid content (TFC) decreased continuously. The antioxidant activity of maize kernels was increased gradually and positively associated with TPC. ZmCHSs in flavonoid biosynthetic pathway played important roles for total flavonoid accumulation at both early and later development stages. The expression pattern of ZmANS corresponded to the accumulation of total anthocyanin during kernel development. These results revealed that developmental stage affected the accumulation of different phenolic compounds, antioxidant activity and related gene expression. The antioxidant activity of maize kernels was dependent on the total phenolic accumulation which was related to the expression profiles of the genes participated in phenolic synthesis.     

用滚筒初清筛清理后小麦品质的变化

为了提高小麦储藏的稳定性,在小麦入仓前先用滚筒初清筛清理,结果显示：容重由773g/L增加到777g/L,水分含量由12.6％降低到12.5％,有机杂质含量由0.4％降低到0.2％,无机杂质含量由0.7％降低到0.3％,不完善粒由13.2％降低到12.0％,破碎粒由2.8％降低到1.9％,清理效果良好.     

不同水肥管理对冬小麦灌浆影响的模拟研究

在河北省衡水市中国-加拿大合作研究试验站,结合田间试验对不同水肥管理条件下冬小麦的灌浆过程进行了研究。结果表明,小麦粒重的大小主要取决于灌浆时间和强度,子粒的灌浆过程可较好地用Logistic函数描述。小麦生长前期的水分胁迫有利于加快其发育进程,促使早抽穗灌浆。灌浆期适宜的水分状况可延缓小麦的灌浆进程,由于较大灌浆速率持续的时间较长,增加千粒重的潜力较大。小麦的群体密度是影响收获粒重的主要因素之一,随着穗密度的增大,灌浆速率和千粒重逐渐降低。随着施氮量的增加,小麦的干粒重下降,这主要与施氮的增穗作用有关。     

Geographic variation for spike and grain characteristics in durum wheat germplasm adapted to dryland conditions

Summary A set of 109 durum wheat accessions, selected from a world collection for their adaptation to dry environments, were further evaluated under moisture-limiting conditions. The entries were subdivided into 9 gene pools based on their country of origin. Data are presented to assess the phenotypic variation and distinctiveness of these pools for some spike and grain features. Analysis of variance revealed highly significant differences among materials of diverse origin for all traits except protein content. Within-country variation was generally wide as regards spike length and 1000-kernel weight. The Ethiopian germplasm presented a remarkable variability and distinctiveness. Entries with interesting values for breeding purposes were detected in most country gene pools. In general, selection of germplasm adapted to harsh environments did not result in a loss of variability for the considered traits, with the possible exception of protein content. Ethiopian entries presented the highest number of significant pairwise character correlations. The two most important traits in a discriminant analysis by country of origin were spike density and 1000-kernel weight. Diversity among gene pools was further assessed by a canonical analysis. The first three canonical variables explained 90% of the total variance. The gene pools of Ethiopia, Greece, Egypt and Jordan appeared clearly distinct from the other germplasm subsets studied. Geographically distinct patterns emerging from this study could be the result of the combined effect of natural and human selection.     

Effect of nitrogen supply on carbon and nitrogen partitioning after flowering in maize

Low nitrogen (N) supply may change assimilate partitioning between plant organs. We measured the effect of N supply on partitioning of recently assimilated ¹³C and recently absorbed ¹⁵N between generative and vegetative plant organs of two maize genotypes (Zea mays L.) 14 d after silking, i.e., during the lag phase of kernel growth. Furthermore, net partitioning of dry matter and N were assessed during grain filling. Plants were grown in a greenhouse in large containers. Our hypothesis was that N deficiency reduces grain set due to low partitioning of carbon (C) and N to the grains during the lag phase and reduces grain yield also because of excessive remobilization of N from the leaves during grain filling. During the lag phase, low N supply increased partitioning of recently assimilated photosynthates towards stem and roots at the expense of partitioning towards reproductive organs. However, despite of diminished sink strength of the reproductive organs for photosynthates, sugar concentrations in the grains of N‐deficient plants were increased, indicating that kernel set and potential kernel weight were not limited by low C supply at the end of the lag phase. In contrast to C, partitioning of recently absorbed N towards the reproductive organs was increased at low N supply at the expense of partitioning towards the roots. This indicates different mechanisms for the regulation of C and N distribution within the plant. During grain filling, biomass partitioning between plant organs was more affected by genotype than by rate of N supply. Nitrogen accumulation in the grains substantially exceeded total N uptake in the plant after flowering. Excess N accumulation in the grains was covered mainly by depletion of stem N at high N supply and by depletion of leaf N at low N supply. However, high concentrations of nonstructural carbohydrates in the stem at maturity indicated that grain yield of N‐deficient plants was not limited by low source strength of N‐depleted leaves.     

3维图像处理系统在稻米品质检测中的应用研究

利用微切片3维图像处理系统对稻米的品质特性进行了探索性的研究。结果表明，借助于3维可视化技术，可以对稻谷的外观品质、营养品质及蒸煮品质等进行更为直观且客观的观察与测定。尤其是在营养成分分布密度的评价、心白米内部组织的分析、蒸煮过程中组织结构变化的观测等方面，取得了传统研究方法难以获得的结果。利用该系统对垩白度的定量化测定，为食品的定量形态学研究开辟了一条新的研究途径。     

鲜湿面抗老化剂复配工艺优化及老化动力学

鲜湿面货架期内硬化主要与淀粉老化密切相关,为抑制鲜湿面老化,该研究以瓜尔豆胶、硬脂酰乳酸钠、水溶性大豆多糖、β-环糊精进行复配,以硬度值为指标,应用响应面进行优化,并通过差示量热扫描仪（differential scanning calorimeter,DSC）研究最佳条件下鲜湿面淀粉的热力学参数及建立老化动力学方程。结果表明：回归得到的二次多项式模型极显著（P<0.0001）,且模型校正决定系数为0.8598,相关系数为0.9389,当瓜尔豆胶添加量为0.4%,硬脂酰乳酸钠添加量为0.22%,水溶性大豆多糖添加量为0.18%,β-环糊精添加量为0.15%时,预测得出的鲜湿面硬度值为48.66 N,验证试验得到的鲜湿面的硬度值为41.01 N;最优条件下制备的鲜湿面较对照组具有更加有序致密的结构;最优条件下制备的鲜湿面融化支链淀粉重结晶所需的热焓,重结晶的增长速度均小于空白对照组;最优条件下制备的鲜湿面成核方式也不断趋近与自发成核。说明添加最优抗老化复配剂能很好地延缓鲜湿面淀粉的回生,为保持鲜湿面的食用品质和延缓鲜湿面的货架期提供参考。     

基于小波变换的小麦硬度声学测定方法研究

信息技术近几十年以来发展迅速,而声学的发展已经有几百年的历史,信息科学与传统的声学相结合产生的信息声学技术成为当代科研领域中的一个热点。小麦颗粒碰撞物体时产生的音频信号含有大量的信息。为此,通过小波变换对小麦音频信号进行处理,提取一些有用的特征参数,利用线性回归分析方法,建立提取的特征参数与小麦硬度之间的回归模型。结果表明,所建模型的线性相关系数r2达到了0.950 5。     

玉米籽粒力学特性的研究进展及应用

玉米籽粒力学特性的研究,揭示了玉米籽粒机械损伤机理,为玉米低损伤收获、干燥、脱粒、加工、贮运及品质鉴定等相关装备的研究提供了理论依据.综述了玉米籽粒力学特性的研究进展,介绍了这一特性在工程中的应用.