β-葡聚糖酶水解小麦秸秆制备纤维寡糖的条件优化

【目的】探索商品化β-葡聚糖酶水解小麦秸秆制备纤维寡糖的最佳条件,为纤维寡糖的工业化生产提供科学依据。【方法】采用浓硫酸和浓盐酸混酸降解微晶纤维素制备纤维寡糖混合物,通过分离纯化得到聚合度为2—5的纤维寡糖单一组分。用所得纤维二糖作为标准品测定小麦秸秆酶解产物中的纤维二糖,并以纤维二糖含量和小麦秸秆转化率为衡量指标,研究酶解反应温度、pH、反应酶底比E/S、反应底物浓度、反应时间对寡糖生成的影响。【结果】采用活性炭柱层析法得到了高纯度的聚合度2-5的纤维寡糖单一组分;当酶解反应温度为50℃、pH为5.5、E/S为0.4、底物浓度为2%、时间10 h时酶解效果最好,小麦秸秆总转化率达到55.57%,纤维二糖得率为148.15 mg•g-1秸秆。【结论】活性炭柱层析可以很好地分离纤维寡糖,得到了聚合度为2—5的纤维寡糖单一组分;酶解小麦秸秆总转化率及纤维二糖得率均提高。     

Association of soil properties and soil and plant iron to iron deficiency response in rice (Oryza Sativa L.)

Abstract

Problems are invariably encountered when attempts are made to explain the variability in Bray percent yields or plant response in terms of soil or plant iron (Fe). To resolve this inconsistency, the present investigation was initiated to identify a combination of soil extractable Fe, soil properties and form of plant Fe that may be used as a measure of Fe deficiency. The study involved 16 diverse soils, using upland rice (Oryza sativa L.) as the test crop and Fe‐EDDHA [ferric ethylenediamine di (o‐hydroxyl‐phenyl acetic acid)] as source of Fe. The results showed that Bray percent yields were neither related to DTPA (diethylenetriamine pentaacetic acid) or EDTA (ethylenediamine tetraacetic acid) extractable Fe nor with total plant Fe. Even the inclusion of pH, lime, organic carbon and clay data in the regression equations was of no value. However, Bray percent yields were significantly and positively (r = 0.57* ) associated with ferrous Fe (Fe²⁺) in 40‐day‐old rice plants. The explanation concerning variability in Bray percent yields obtained on diverse soils could be increased about one and half 2 times (R²= 0.59*) if the contribution of lime and soil pH was also incorporated in the stepwise regression analysis. The individual contribution to R of lime, pi respectively. Thus, it appears that Fe²⁺ concentration in plants (along with soil pH) may identify Fe deficiency. The critical limit to separate Fe deficient from green rice plants was set at 45 ug Fe²⁺/g in the leaves.     

麦田套种棉花促早栽培技术研究

通过４年的试验研究，解决了麦田套种棉花的晚发晚熟问题，在保证麦棉高产高效的基础上使套种棉花１０月５日前的吐絮率达９０％以上，套种田的小麦能够适时播种，麦棉能够倒茬换地，从而有效地提高厂麦棉套种田的总体经济效益。其技术核心是：高密度，巧化控，塑造矮株，以内围大铃取胜，合理运筹水肥达到早发早熟高产高效的目的。     

啤酒大麦与饲用大麦籽粒结构和淀粉粒的比较研究

为了探索大麦籽粒结构和淀粉粒与其用途的关系，利用扫描电子显微镜（SEM）和差示扫描量热分析仪（DSC）对啤酒大麦（港啤1号和扬农啤2号）与饲用大麦（扬饲麦1号）的籽粒结构和淀粉粒进行了比较研究。结果表明，3个品种表现相似的胚乳结构，但啤酒大麦的淀粉粒与蛋白质结合不紧密，饲用大麦的淀粉粒和蛋白质结合较紧密，且饲用大麦的蛋白质基质含量高于啤酒大麦。采用碱处理和差速沉淀法分离了籽粒胚乳大、中、小淀粉粒，虽然品种间淀粉粒的形态无明显差别，但大、中、小淀粉粒的大小和含量差异很大。DSC分析所得参数表明，大淀粉粒糊化时的起始温度（To）、峰值温度（Tp）和终结温度（n）高于相同品种的中、小淀粉粒，且糊化过程所需的热焓（△H）也较高。     

玉米子粒灌浆及种子萌发特性的粒位效应研究

对粒重不同的2个纯合稳定普通玉米自交系及其正反交当代果穗上、中、下不同部位子粒的灌浆进程及成熟种子的电导率和萌发特性研究结果表明:①不同部位子粒百粒重均表现为下部>中部>上部,杂交当代的百粒重高于母本自交系;子粒灌浆速率的高低和有效灌浆期的长短是导致不同材料及不同部位子粒百粒重差异的主要原因。②中部子粒的电导率小于上、下部子粒,种子发芽率、发芽指数、发芽生长指数、贮藏物质消耗率和运转率大于上、下部子粒。种子萌发及幼苗特性的一致性也与粒位效应有关。     

Nutrient composition of groundnut cultures (Arachis hypogaea L.) in relation to their kernel size

Seven varieties of groundnuts of varying kernel size were selected to study the relation between kernel size and nutritional quality. Results indicated that no significant (r=0.22) difference was found in oil contents among the various varieties which ranged from 46–52 percent. Protein contents ranged from 17–25.2 percent. Protein content of small seed varieties was high compared to bold seeded varieties, whereas sugar content of bold seeded varieties was higher. No significant differences in amino acid and fatty acid compositions were observed among the varieties tested. In vitro digestibility of protein tended to be slightly less but not significantly so in bold seeded varieties compared to small and medium size varieties. Niacin content of bold seeded varieties was slightly higher compared to other varieties.     

普通玉米单交种与高油玉米杂交当代子粒化学成分的遗传分析

试验以吉林省主推的普通玉米单交种为母本,以高油玉米为父本进行人工杂交,研究双亲对杂交当代子粒的脂肪、蛋白质和淀粉含量的影响.结果表明:①母本对杂交当代子粒脂肪含量的影响大于父本,杂交当代子粒的脂肪含量与其双亲的关系是:普通玉米单交种×高油玉米自交系杂交当代子粒的脂肪含量=0.60P₁+0.40P₂;普通玉米单交种×高油玉米单交种杂交当代子粒的脂肪含量=0.65P₁+0.35P₂;普通玉米单交种×高油玉米群体的杂交当代子     

Magnetic resonance imaging and analyses of tempering processes in rice kernels

This research involved a magnetic resonance imaging (MRI) technique that was applied to examine water distribution and migration in single rice kernels during the tempering process. The imaging experiments were performed in a Bruker 9.4T MRI system. Three-dimensional spin-echo (SE) imaging sequences were optimized by adjusting the scanning parameters of echo time (TE) and repetition time (TR) to obtain images with maximum contrast. The MR images showed that the moisture distribution in the rice kernel is non-uniform and compartmental. The embryo region exhibited much higher MR signal intensity than the starchy endosperm portion. The tempering process was analyzed with spatial-temporal signal intensities of the endosperm following the drying process of the rice kernel. The transient change of the signal intensities in the endosperm was well fitted with a double exponential function suggesting that both convection and diffusion contributed to the reduction of the moisture gradient within the rice kernel during tempering. This hypothesis was further supported by the experimental data of the insulated rice kernel whose convective mass transfer was excluded. The experimental results revealed that MR imaging of rice kernels could be used as an efficient tool to examine the mechanisms of moisture migration within cereal grains.     

Responses to divergent selection for cob color in maize

Previous studies showed that in materials derived from maize (Zea mays L.) single cross A632 × Mu195 there is association between agronomic traits and cob color (affected by P1 gene). Objectives of this study were to evaluate the responses to divergent selection for cob color in F₂-Syn 0 (obtained by selfing A632 × Mu195), estimate the genetic parameters of the involved putative quantitative trait loci (QTL), and evaluate the responses to divergent selection for cob color in A632 and Mu195 backgrounds. The populations selected in F₂-Syn 0 for red (R0) or white cob (W0) were tested in four trials. Differences between R0 and W0 were found for grain yield (85.0 vs. 75.0 g/plant) and other traits; most of these differences were related to leaf number/plant. Then, population F₂-Syn 1, derived after one random mating generation, was divergently selected for cob color, thus producing R1 and W1. Populations R0, W0, R1, and W1 were tested in two trials, allowing the estimate of genetic effects and recombination frequencies for putative QTL of several traits. Finally, a divergent selection for cob color was conducted in segregating materials of A632 and Mu195 backgrounds. The two pairs of selected populations were compared in two trials; the responses were similar to those detected by comparing R0 and W0. We conclude that divergent selection for cob color in F₂-Syn 0 is effective for several traits, that such responses are due to putative QTL linked to P1, and that selection is also effective in different genetic backgrounds.     

顾及空间效应的县域收入分布时空演进研究——以广西为例

运用随机Kernel密度函数,将空间因素引入研究框架,对1998~2005年广西县域收入分布演进进行分析。结果表明,广西县域收入差距具有持续稳固的特点;区域收入分布演进总体呈单峰俱乐部收敛,表现出多俱乐部收敛的趋势,贫穷俱乐部的规模远大于其他较高收入俱乐部;县域收入分布演进明显具有空间依赖性,近邻效应显著,邻域富裕的县域向较高收入水平演进的机会较大,并且导致县域经济增长表现为局部空间俱乐部收敛特征。