饲料添加剂用黄芩甙提取工艺条件的优化

为了优化饲料添加剂用黄芩甙提取工艺，采用L₉(3⁴)正交试验设计方法，对浸提和酸沉工艺进行了优化试验研究，采用紫外分光光度法对提取物黄芩甙进行含量测定。结果表明：浸提较优工艺为A₃ B₃ C₂，即浸提时间1.5 h，浸提温度100℃，浸提pH 7.0；酸沉较优工艺为A′₂ B′₃ C′₁ D′₃，即保温时间1.0 h，保温温度80℃，保温pH 1.0，静置时间12 h。经两次正交试验设计所得优化提取工艺可行，提取率为91.56％，含量为94.12％。     

呼伦贝尔草甸草原不同显热通量观测方法比较

显热通量（sensible heat flux，H）是反映地表湍流运动的重要参数，准确获取该参数对于区域内热量交换规律的认识和农业生产及水资源的有效管理具有重要意义。涡动相关仪（eddy covariance system，EC）和大孔径闪烁仪（large aperture scintillometer，LAS）是目前生态系统水热通量的主要测量手段，但两者观测范围的空间尺度存在差异。该研究以呼伦贝尔草甸草原生态系统为对象，通过对比分析两种方法观测的显热通量（H_LAS和H_EC）变化特征，对两者之间的差异（ΔH）及产生原因进行探究，并且定量研究了不同因子对ΔH的影响程度。结果表明，在不同时间尺度内，H_LAS和H_EC的变化趋势基本一致，显热通量主要受到净辐射的驱动作用，同时ΔH与净辐射存在正相关性；对应时刻H_LAS和H_EC之间线性回归方程斜率为1.13，拟合优度R²为0.81，说明大孔径闪烁仪在草甸草原区有着很好的适用性；EC能量平衡闭合程度会影响H_LAS和H_EC之间差异，剔除能量平衡闭合率（energy balance ratio，EBR）小于0.8的数据后，H_LAS和H_EC之间线性回归方程斜率减小至1.05，说明能量平衡闭合程度越高ΔH越小；净辐射（net radiation，R_n）、风速（wind speed，WS）、波文比（Bowen ratio，Bowen）和饱和水汽压差（saturated water vapor pressure difference，VPD）与ΔH之间相关性显著，是ΔH的主要气象环境因子；ΔH单个影响因子的解释能力从高到低依次为净辐射、风速、EC能量平衡闭合率、饱和水汽压差、波文比，任意两个不同影响因子之间均呈现双因子增强作用，解释能力较高的交互影响因子为净辐射/风速和风速/波文比。研究结果有利于准确理解LAS与EC显热通量观测过程中的空间尺度效应，同时可为区域尺度扩展和遥感地面验证过程中通量数据的质量控制提供科学参考依据。     

低温胁迫对圆叶决明的伤害及施用Ca肥防护效果的研究

圆叶决明在0℃低温下分别胁迫6、12、18、24 h后,叶片叶绿素总量较对照(25℃)下降21.89%、26.04%、28.16%、29.31%,可溶性蛋白质含量、H₂O₂含量和·O^-₂净产生速率随胁迫时间增加,活性氧清除酶SOD的活性随胁迫时间先上升后下降。施Ca²⁺处理可明显降低圆叶决明叶片·O^-₂净产生速率、H₂O₂含量和细胞质膜的电解质渗透率,同时提高了叶绿素含量和抑制活性氧的产生,其中以0.5 mmol/L浓度的CaCl₂处理效果为最佳,说明Ca²⁺对低温胁迫下圆叶决明的膜结构起有效的保护作用。     

90℃下老化时结晶磷铁矿的生成条件

溶液中Fe与P反应并不直接生成结晶磷铁矿,中间经过无定形阶段。溶液的pH对Fe-P无定形物质的组成及由无定形Fe-P向结晶磷铁矿转化都有很重要的作用。在90°下老化80天,用加入的Fe(NO₃)₃和NaH₂PO₄浓度及混合后的溶液pH计算得到的﹝Fe³⁺﹞﹝H²PO₄^-﹞值可以较好地判断溶液中是否会有结晶磷铁矿生成。本文的实验条件下,结晶磷铁矿生成的条件是-log{﹝Fe³⁺﹞﹝H₂PO₄^-﹞} ≤ 6.09(加入的P/Fe比 ≥ 1)。     

猪粪堆肥过程中NH3和H2S的释放及除臭微生物的筛选研究

为了治理粪便臭气污染，测定了猪粪好氧堆肥过程中NH₃和H₂S的释放量以及堆肥温度、pH值、含水率、水溶性铵态氮等指标。结果表明，NH₃在前20天释放量占总释放量的84.6%、H₂S在前13天释放量占总释放量的100%。因此，在堆肥初期的前20天是控制臭气的最佳时期。并从畜禽粪便、垃圾、土壤和堆肥中分离、纯化了一些微生物，经过初筛得到能利用NH₃的微生物41株，经过复筛得到脱除H₂S较好的细菌一株，与对照相比其去除率达85.7%，经鉴定该菌是松鼠葡萄球菌。     

La(NO3)3 对盐胁迫下黑麦草幼苗生长及抗逆生理特性的影响

为探讨稀土元素镧(La)对牧草盐胁迫伤害的缓解作用, 采用水培法研究了叶面喷施20 mg·L^-1La(NO₃)₃ 对NaCl 胁迫下黑麦草幼苗生长及其抗逆生理特性的影响。结果表明: 盐胁迫显著抑制黑麦草幼苗的生长, 提高叶片电解质渗漏率及丙二醛(MDA)、O₂^- 和H₂O₂ 含量, 其作用随盐浓度的增大而增强。超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性和抗坏血酸(AsA)、谷胱甘肽(GSH)、可溶性蛋白质、脯氨酸含量随盐浓度增大呈先升后降趋势, 可溶性糖和Na⁺/K⁺比逐渐增大, 质膜H⁺-ATP 酶活性逐渐降低, 过氧化物酶(POD)活性及POD 同功酶数量表达增强。喷施La(NO₃)₃ 处理可降低盐胁迫下黑麦草幼苗叶片的O₂^- 和H₂O₂ 含量, 提高SOD、CAT、POD、APX 和质膜H⁺-ATP 酶的活性及POD 同功酶的表达, 使AsA、GSH、可溶性蛋白质、可溶性糖和游离脯氨酸含量及幼苗生物量增加, Na⁺/K⁺比降低。表明La(NO₃)₃ 可通过提高抗氧化系统的活性和积累渗透溶质减轻盐胁迫伤害, 从而提高黑麦草的耐盐性。     

类芽孢杆菌Bg1抗真菌蛋白的分离及其特性分析

为了明确类芽孢杆菌(Paenibacillus sp.)Bg1的主要抗真菌物质及其特性,本文利用抑菌圈法测定了Bg1抗菌蛋白在各种处理条件下抑菌活性的稳定性;通过60%硫酸铵沉淀、DEAE-Sephadex A50离子交换层析及Sephadex G100凝胶过滤层析进行了抗菌蛋白的分离纯化,以SDS-PAGE进行了其纯度检测。结果表明,28~100℃处理30 min、4℃存放55 d及在pH值3~7范围内菌株Bg1抗菌蛋白抑菌活性均无显著性变化,但pH值!8显著影响其抑菌活性,蛋白酶处理则使其抑菌活性完全丧失;纯化后所得抗菌蛋白分子量约10 KD。据此可知,类芽孢杆菌Bg1主要抗菌活性物质为低分子量蛋白,其对热和酸性条件及贮存时间稳定性好,具有进一步开发应用的潜能。     

用电导频散法研究Cl-、SO42-和H2PO4-阴离子与土壤的相互作用

本文介绍了采用电导频散装置测量分别含有10^-4mol/LHCl、5×10^-5mol/L H₂SO₄和10^-4mol/L H₃PO₄的黄棕壤、棕壤、黑土和砖红壤悬液(20-30g/kg)的电导频散曲线,频散曲线上均呈现频率范围相当宽的坪区,频散曲线的特性分析结果表明,黄棕壤和棕壤在3种酸溶液中的始散频率(0.6-1kHz)低于黑土悬液(16-28kHz),而砖红壤的始散频率最高(25-47kHz;Cl^-、SO₄^2-和H₂PO₄^-离子与4种土壤的相对亲合力(REC_1.5/REC_tp-1)顺序为Cl^- < SO₄^2- < H₂PO₄^-,在不同土壤之间的顺序则随酸溶液而异.     

牛粪湿法厌氧消化规律及载体影响的研究

在35℃条件下，观察牛粪厌氧消化的沼气产量和生物指标的变化规律及聚丙烯网状空心球、玻璃纤维和碳纤维膜载体对牛粪厌氧消化性能的影响。结果表明：5%牛粪在厌氧发酵过程中，pH值在发酵的第3 d降到最低，在发酵的第7 d升高到7以上；沼气的产量约在发酵的第9 d达到高峰，而后逐渐降低；COD的去除主要发生在发酵的第4～8 d；发酵产物细菌数量在发酵第6 d达到高峰，在第12 d降低到一个基本相对稳定的水平；辅酶F₄₂₀活性与其细菌数量在时间和数量方面有着相同的变化规律。聚丙烯网状球形载体表面附着较多的微生物，由此延长产气高峰期，并显著提高沼气产量(p<0.05)，以及显著降低反应器厌氧微生物的流失(p<0.01)。     

土壤中具有蛋白酶活性的酶-腐殖质复合物的提取及其性质的研究

用中性0.1M焦磷酸钠提取,经硫酸铵分段,丙酮沉淀,从土壤中获得了具有蛋白酶活性的酶-腐殖质复合物,其特性:反应最适pH为9.0,反映最适温度为50°-60℃,温度系数Q₁₀(17°-40℃)为1.93,K_m值为0.97-1.00毫克酪素/毫升,V_max值为74.91-75.35毫克酪氨酸/克·24小时,与原位土壤蛋白酶相比,反应最适pH往碱性偏移,反应最适温度及K_m值变小,热稳性降低,Q₁₀和V_amx值增大.土壤经超声波分散后,可以用各种盐缓冲液将其中具有蛋白酶活性的酶-腐殖质复合物提取出来,其收率依次为水<0.1M磷酸盐-0.3M KCl-0.01MEDTA<三羟甲基氨基甲烷(pH7)<0.2M碳酸氢钠<0.05M磷酸盐-柠檬酸<0.1M焦磷酸钠溶液.     

Agricultural potential of Mediterranean grain and forage legumes: Key differences between and within Vicia species in terms of phenology, yield, and agronomy give insight into plant adaptation to semi-arid environments

In order to identify key adaptive traits which affect productivity in Mediterranean grain and forage legumes and simultaneously determine the agricultural potential of a wide range of Vicia species, germplasm collected from the wild throughout the eastern Mediterranean was grown under semi-arid conditions in Tel Hadya, Syria (313 mm growing season rainfall). These included species currently in use in Mediterranean agriculture, such as V. sativa L., as well as those more widely used in the past-such as V. ervilia L., but also a broad selection from Section Narbonensis (B. Fedtsch. ex Radzhi) Maxted, including V. narbonensis L, V. johannis Tamamsch., V. hyaeniscyamus Mout., V. serratifolia Jacq., and V. kalakhensis Khattab et al. V. faba, a near relative of the taxa in Section Narbonensis, was included as a domesticated control. Where applicable, a representative range of subspecies was used. Accessions were chosen from a wide range of habitats in terms of latitude (31.02–40.72 decimal^o), longitude (27.1–43.17 decimal^o), altitude (20–1510 m), rainfall (180–1700 mm/yr) and soil depth (5–50 cm) in order to maximise diversity within species. Agricultural potential was determined by measuring seed, hay and biological yield, as well as agronomic traits such as harvest index, standing crop height, and seed size. The comparative influence of phenology and key agronomic traits such as plant habit and seed size on productivity varied tremendously between species, depending on their reproductive strategies. In V. sativa and V. ervilia, the smaller seed species which rely on long vegetative phases and growing seasons to accumulate sufficient biomass to set seed, and in which there was comparatively little agronomic variation, phenology had a large impact on yield. In early emerging taxa such as V. ervilia and V. s. subsp. sativa, with built-in long vegetative phases and growing seasons, seed yield was negatively correlated with flower ing (r = –0.86 to –0.88), whereas the opposite was the case for later emerging taxa such as V. s. subsp. nigra (L.) Ehrh. (r = 0.95). Within V. narbonensis and relatives, the larger seeded Vicia species which rely on more conservative reproductive strategies where high seedling vigour associated with large seeds enables the species to enter reproductive phases relatively early, phenology had a much smaller impact on yield than did variation of key traits such as seed weight, plant habit and pod shattering. Among the undomesticated germplasm harvest indices ranged from 0.09–0.31, hay yields from 0.1–3.4 t/ha, seed yield from 0–2.0 t/ha, and dry matter at maturity from 1.6–6.5 t/ha. Sub-specific taxonomy was crucial in determining agronomic potential. V. narbonensis var. aegyptiaca Kornhuber ex Asch. et Schweinf. showed the most potential, combining an upright habit, large seeds (212 mg) and tendency to retain intact pods after maturity, with the highest yield, harvest index and crop height of all the wild Vicia species. V. sativa subsp. sativa, V. ervilia and V. narbonensis var. narbonensis were less productive, but still showed agricultural potential. The smaller seeded V. narbonensis, var. affinis, var. jordanica H. Schäf. and var. salmonea (Mout.) H. Schäf., and their close relatives V. johannis, V. hyaeniscyamus, V. serratifolia and V. kalakhensis have little to offer Mediterranean agriculture on the basis of poor agronomy.     

Changes in trace element speciation in kola north surface waters during snow melt

The powerful mass-flow of melt water during the brief period of spring thaw provides a surge of pollutants and causes extremely toxic short term conditions. Together with the increase in total metal concentrations during this period, a redistribution in metal speciation occurs that increases the proportion of more toxic forms. Concentrations of ion-exchangeable fractions of nickel (Ni), copper (Cu), aluminium (Al), and manganese (Mn) show strong negative correlations with pH. The sum of complex metal species shows a strong positive correlation with total organic carbon (TOC). A data analysis model based on relationships observed between key parameters and metal behaviour together with gidrological data allowed an assessmrnt of the metal impact on waterbodies from accumulated airborne pollution (Ni, Cu) as well as from accelerated leaching from watersheds (Al, Mn).     

On the Taxonomy of the Members of ‘Saccharum Complex’

The difficulty and problems encountered in the study of cultivated plants, in general and sugarcane, in particular has been indicated. In order to understand these problems, a brief review on the taxonomy of Saccharum and closely related taxa, namely, Erianthus, Sclerostachya, Narenga and Miscanthus (generally known as ‘Saccharum complex’) has been given. A short account on the important morphological features that are specific to sugarcane has also been stated as classification is commonly based on such morphological characters. A note has been added on the chromosome number, origin, and distribution of the species of ‘Saccharum complex’ members. Taxonomic keys have been devised for identification of the genera of Saccharinae and for the species of Saccharum and Erianthus occurring in India. A new combination, Sclerostachya fallax (Balansa) Amalraj et Balasundaram, has also been proposed.     

The major features of an infestation by the invasive weed legume gorse (Ulex europaeus) on volcanic soils in Hawaii

Gorse (Ulex europaeus) infestation occupies over 4,000 ha of agriculture and conservation lands on the southeastern slope of Mauna Kea on the Island of Hawaii. The aim of this investigation is to identify ecological features associated with this weed invasion by comparing the gorse-infested areas to the surrounding uninfested areas of this landscape. The soils within the gorse infestation are more acidic, resulting in higher levels of KCl-extractable Al and lower levels of Mehlich III-extractable Ca, Mg, Mn, and Zn. Yet, gorse accumulates higher concentrations of Ca, Zn and, Cu than the kikuyu grass (Pennesitum clandestinum), which is ubiquitous throughout the site. The Ca:Al and Mg:Al molar charge ratios of the soils are lowest within the epicenter of the gorse infestation, while the molar ratios are highest in the gorse apical stem tissues. All gorse plants are nodulated and have higher nitrogen contents than the surrounding kikuyu grass. Furthermore, the δ¹⁵N of the gorse stem tissues approaches 0‰, suggesting that nitrogen is being symbiotically fixed from the atmosphere. Characterization of the Bradyrhizobium isolated from gorse nodules shows similarities and distinctions to Bradyrhizobium isolated from the endemic legume koa (Acacia koa) within the same location. Population densities of the indigenous Bradyrhizobium are higher within the gorse rhizosphere than the kikuyu grass. Soil acidification, nutrient depletion, and symbiotic nitrogen fixation distinguish gorse-infested areas from the surrounding uninfested areas. These observations suggest that gorse has a competitive advantage over kikuyu grass under conditions of soil nutrient deficiency.     

Nematofauna associated with exotic and native leguminous plant species in West Africa: effect of<Emphasis Type="Italic"> Glomus intraradices</Emphasis> arbuscular mycorrhizal symbiosis

Ten leguminous trees, four exotic species (Australian Acacia) and six indigenous species (three Sahelian Acacia spp. and three Sesbania spp.), were grown for 4 months in a natural Sahelian soil inoculated with or without the endomycorrhizal fungus, Glomus intraradices. In control trials, the determinant factor structuring the soil nematode fauna was the plant species, related plants having a similar influence on the nematode community in the soil. Soil nematode abundance increased from exotic acacias (3.3 g^-1 dry soil) to native acacias (11.5 g^-1 dry soil) and Sesbania species (17.6 g^-1 dry soil). Plant feeding nematodes (mainly Scutellonema and Tylenchorhynchus) were significantly less abundant under exotic acacias (1.4 g^-1 dry soil) than under native acacias (7.2 g^-1 dry soil) or Sesbania species (7.3 g^-1 dry soil). Bacterial feeding nematode density increased from exotic acacias (1.2 g^-1 dry soil) to native acacias (3.0 g^-1 dry soil) and Sesbania species (7.7 g^-1 dry soil) as total densities. However, the differences in the structure of the nematode communities between plant groups were suppressed in the presence of the mycorrhizal fungus. In fact, no difference in nematode densities remained between plant groups when G. intraradices developed in several dominant taxa belonging to different trophic groups, particularly: Tylenchorhynchus, Apelenchina, Cephalobus and Dorylaimoidea. This study clearly indicated that inoculation with the arbuscular mycorrhizal fungus G. intraradices diminished the plant-specific effect on the structure of the soil nematode community.     

Genetic diversity of rhizobia associated with indigenous legumes in different regions of Flanders (Belgium)

We investigated the diversity of rhizobia isolated from different indigenous legumes in Flanders (Belgium). A total of 3810 bacterial strains were analysed originating from 43 plant species. Based on rep-PCR clustering, 16S rRNA gene and recA gene sequence analysis, these isolates belonged to Bradyrhizobium, Ensifer (Sinorhizobium), Mesorhizobium and Rhizobium. Of the genera encountered, Rhizobium was the most abundant (62%) and especially the species Rhizobiumleguminosarum, followed by Ensifer (19%), Bradyrhizobium (14%) and finally Mesorhizobium (5%). For two rep-clusters only low similarity values with other genera were found for both the 16S rRNA and recA genes, suggesting that these may represent a new genus with close relationship to Rhodopseudomonas and Bradyrhizobium. Primers for the symbiotic genes nodC and nifH were optimized and a phylogenetic sequence analysis revealed the presence of different symbiovars including genistearum, glycinearum, loti, meliloti, officinalis, trifolii and viciae. Moreover, three new nodC types were assigned to strains originating from Ononis, Robinia and Wisteria, respectively. Discriminant and MANOVA analysis confirmed the correlation of symbiosis genes with certain bacterial genera and less with the host plant. Multiple symbiovars can be present within the same host plant, suggesting the promiscuity of these plants. Moreover, the ecoregion did not contribute to the separation of the bacterial endosymbionts. Our results reveal a large diversity of rhizobia associated with indigenous legumes in Flanders. Most of the legumes harboured more than one rhizobial endosymbiont in their root nodules indicating the importance of including sufficient isolates per plant in diversity studies.     

Powdery Mildew Resistance in a Collection of Chinese Barley Varieties

One hundred and forty-seven Chinese barley varieties maintained at the Gene Bank of the National Barley Improvement Centre, Zhejiang, and 84 progenies from these varieties were tested at the seedling stage for their reaction to 32 selected pathotypes of Blumeria graminis f. sp. hordei. Eighteen resistance spectra were identified comprising single or combined resistances from eight known (Ml(Bw), Ml(Ch), Mla7, Mla8, Mla9, Mla13, MlaRu4 and Mlg) and six unknown resistance genes. The most frequent gene was Ml(Bw), which was found in 69 varieties and previously detected in only a few European winter barley varieties. The genes Mla8 and Ml(Ch) were also often present, but other resistance genes were rare. After inoculation, considerably fewer pathogen colonies were observed in ‘Aiganqi’ and one line of ‘Tong5’. Twenty varieties were composed of lines with different resistance genes. China is likely to be a region of origin of the genes Ml(Bw), Mla7, as well as three unknown genes found in original landraces and perhaps another three unknown genes detected in cultivars bred in China. The resistances of varieties from the Zhejiang province and those originating from 11 other Chinese provinces were quite different. Unfortunately, none of the varieties are promising sources of resistance to powdery mildew and China does not seem to be a region suitable for identifying such sources.     

Polymorphism of high molecular weight glutenin subunits in three species of Aegilops

A collection of 136 accessions of Aegilops umbellulata (39), Ae. comosa (75) and Ae. markgrafii (22) was analysed for high-molecular-weight (HMW) glutenin subunits composition. The homogeneity of the accessions was studied and 55.1% of the collection was homogeneous for HMW glutenin subunits (29 Ae. umbellulata, 33 Ae. comosa and 14 Ae. markgrafii). The HMW glutenin subunits of Ae. umbellulata are encoded by the Glu-U1 locus; in Ae. comosa results showed that this proteins are encoded at the 1M chromosome, and the locus was named Glu-M1. In Ae. markgrafii it was assumed that HMW glutenin subunits were encoded by an homoeologous locus and it was named Glu-C1. All the accessions of Ae. umbellulata and Ae. markgrafii expressed both, x-type and y-type subunits. Among the Ae. comosa accessions, only one expressed an x-type subunit alone. All the accessions of Ae. umbellulata and some of Ae. comosa had x-type glutenins of higher molecular weights than those commonly present in bread wheat. A total of 8 alleles were detected at the Glu-U1 locus, 11 at the Glu-M1 and 4 at the Glu-C1. The new HMW glutenin variation found in this work suggests their possible utilisation in breeding for wheat quality.