硝态氮对大豆根瘤性状的影响

选取黑龙江省第三积温带主栽大豆品种黑农35为材料,采用水培方法,在大豆移栽后28、35、42、49 d取样,对根瘤的物理性状(根瘤干重、根瘤数和单个根瘤干重)进行动态分析,研究了硝态氮对大豆根瘤性状的影响.结果表明:从移栽后第28天开始生物固氮处理根瘤数明显增加,而施用硝态氮根瘤数基本不变,硝态氮抑制了大豆根瘤形成,而单个根瘤干重增加较大.从根瘤密度来看,硝态氮降低大豆根瘤在根系上分配密度,在第28天生物固氮处理每个根上结瘤124.84个,而施用硝态氮每个根上结瘤22.84个.     

铵硝配比对大豆生长及结瘤固氮的影响

通过水培方法在5种不同铵硝配比下,研究不同氮形态及接种根瘤菌对大豆生长、结瘤固氮的影响及其生理机制。结果表明,不同铵硝配比对大豆植株生长、产量、生物固氮及氮效率等影响显著,随硝氮比例增加,植株生物量、籽粒产量、结瘤固氮及氮效率等指标均呈现先增加后降低的趋势,以铵硝比25:75处理效果最佳,总体表现为铵硝比25:75≥0:100>50:50>75:25>100:0。较高铵硝比（≥50:50）严重抑制了大豆根系的伸长生长、根瘤的形成及其固氮酶的活性,从而降低了生物固氮的贡献率,最终导致大豆产量及氮素效率的降低。接种根瘤菌显著增加大豆产量和籽粒含氮量,并与铵硝比之间存在协同效应。铵硝比为25:75时接种根瘤菌,氮效率最高,最有利于大豆生长及籽粒产量的形成。研究结果对优化大豆水培营养液配方以及指导农田生产中氮素合理施用均有较强的借鉴作用。     

磷和根瘤菌交互作用对大豆结瘤和生长的影响

为了阐明营养液中磷浓度和不同数量根瘤菌的交互作用对大豆结瘤和生长的影响,在营养液培养条件下,进行3种磷水平[P1-0、P2-4和P3-30(μmol P·I-1)]和3种根瘤菌浓度[RI-102、R2-103.5和R3-105(CFU·mL-1)]处理,培养大豆25 d,测定大豆生物量和根瘤性状指标.结果表明:在相同根瘤菌数量条件下,不同磷浓度对大豆总生物量的影响不大,对根冠比的影响较大营养液中接种的根瘤菌浓度越高,根瘤原基数量越夫,低磷明显抑制根瘤原基发育形成根瘤,进而减少了低磷处理大豆根瘤数量从P1到P3,R1恨瘤菌浓度处理根瘤原基形成根瘤的几率分别为:79%、86%和100%.营养液中磷浓度促进生物量向根瘤中分配,高磷处理相对根瘤生物量较高随着生育进程,大豆各组织器官含磷量逐渐降低,在所有取样时期含磷量均表现为根瘤>根>地上部;含氮量表现为根瘤>地上部>根.可见磷和根瘤菌对大豆生长和结瘤形成有交互作用.     

缺磷胁迫对大豆根瘤生长和结瘤固氮的影响

采用砂培培养方法研究了缺磷胁迫对大豆根瘤生长和结瘤固氮的影响.结果表明:缺磷胁迫抑制了大豆根瘤的生长,表现为根瘤干重重下降,根瘤数量减少;缺磷胁迫显著降低了大豆的固氮能力,表现为根瘤吲氮酶活性和豆血红蛋白含量降低;缺磷胁迫降低了大豆的固氮量,固氮量随磷水平的增加而增加,随着生育时期的推进,固氮量表现为先增加后降低再增加的趋势,无磷(0μmol·L~(-1))与高磷(50 μmo·L~(-1))以及低磷(30μmol·L~(-1))与高磷处理间均达到了5%的显著差异.因此,缺磷胁迫抑制了大豆的结瘤固氮作用,使大豆的同氮效率降低.     

土壤有效磷含量对大豆植株磷素含量和土壤有效N、P、K含量的影响

土壤有效磷含量影响大豆植株对N、P、K的吸收利用,进而影响大豆植株的生长发育和产量形成。以吉育89为材料,在大豆不同生长时期测定大豆植株磷素含量和土壤N、P、K含量,研究其随土壤有效磷含量升高而发生变化的规律。结果表明:在取样的4个时期里,植株磷素含量均随土壤有效磷含量的升高呈单峰曲线变化,在土壤磷素水平为30 mg·kg~(-1)时,植株磷素含量达到最大;5个处理的土壤速效磷含量变化趋势都是先下降,在收获期由于土壤自身的磷素补偿作用而有所升高;在各生育时期的土壤中的硝态氮和速效钾含量最低值都出现在有效磷含量为30 mg·kg~(-1)处理,而土壤速效磷含量为10和50 mg·kg~(-1)两个处理的硝态氮和速效钾含量一直较高,说明低磷和高磷土壤对植株氮素吸收有抑制作用。土壤有效钾含量的变化情况与硝态氮相似,均是随土壤有效磷含量升高而呈单峰曲线变化。说明N、P、K肥的合理配比均能够提高肥料的作用效果。     

大豆结瘤固氮的分子生理研究

有关豆科作物共生固氮的研究已有170 a的历史。而豆科结瘤固氮的分子生理研究,仅仅是最近30 a的事情。从影响大豆结瘤固氮的生理因子角度,评述了豆科作物的结瘤自动调控机制,进一步在分子水平上阐述了生长素、硝态氮、黄酮类等生理调控物质对大豆结瘤固氮的影响。生长素调节根瘤菌侵染位点和根瘤形成后的生长;可通过控制结瘤的角度来减少土壤硝态氮对大豆结瘤固氮能力的抑制;黄酮类物质在根瘤发育和结瘤基因诱导中起重要作用;乙烯抑制结瘤信号的前期过程,调整根瘤形成的空间分布。详细、系统地从作物-微生物之间关系出发,研究引起豆科作物根瘤形成和固氮系统的整体信号传导、蛋白和代谢过程,是未来大豆共生固氮分子生理研究应该注重的方向。     

施氮对结瘤和非结瘤近等位基因大豆生长和固氮性状的影响

以结瘤和非结瘤近等位基因大豆品系为材料,利用砂培方式,分析了不同供氮水平对大豆生长、碳氮代谢、结瘤和固氮的影响.结果表明:供氮水平直接影响大豆生物量,结瘤大豆在N2水平(54 mg尿素·kg-1砂)时生物量达到最大(9.16 g·株-1);非结瘤大豆在N4水平(216 mg尿素·kg-1砂)时生物量达到最大(6.36 g·株-1).植株体内碳氮含量与生物量的变化趋势相同.此外,结瘤品系N2水平大豆根瘤数最多(205个·株-1),极显著高于除N4以外的其它处理(P＜0.01),该水平的共生固氮量最大,为275.92 mg·株-1,且与N3、N4、N5处理间差异极显著(P＜0.01).因此,结瘤和非结瘤大豆对外源氮的需求存在显著差异,该试验条件下的氮阻遏阈值为N2水平,即54 mg尿素·kg-1砂.     

不同形态氮对大豆根瘤生长及固氮的影响

采用框栽的培养方法,通过施用不同形态氮肥,探讨不同形态氮对大豆根瘤生长、含氮量、氮积累量以及固氮酶活性的影响.结果表明:不同形态的氮源,对根瘤干重、数量有促进作用,同时增加了根瘤中的含氮量和氮积累量.根瘤干重及数量的变化均为铵态氮(N2)＞蛋白氮(N4)＞硝态氮(N1)＞氨基酸态氮(N3)＞酰胺态氮(N5)＞生物固氮(N0),其中N0处理的根瘤干重、数量最少,而N2处理的根瘤干重和数量最多.根瘤含氮量的变化为N1＞N4＞N5＞N2＞N3＞N0,其中N1处理下的根瘤中的根瘤含氮量最高,N1、N4和N5各处理与N0处理间差异显著(P＜5%).而氮积累的变化为N2＞N4＞N1＞N5＞N3＞N0,各处理与N0处理相比,差异极显著(P＜1%),与含氮量的变化趋势略有不同.添加不同形态的氮源对根瘤固氮酶活性有抑制作用,其变化趋势为N0＞N5＞N3＞N2＞N4＞N1,N0处理的固氮酶活性最高.     

淹涝胁迫和氮形态对苗期玉米营养特性的影响

采用砂培培养方法,比较研究两种水分条件和3种供氮形态处理对苗期玉米根、茎鞘、叶生物量干重及其氮、磷、钾含量及分配的影响。结果表明,非淹涝胁迫条件下铵硝态氮混合处理(AN)玉米生物量干重及氮、磷、钾累积量最高;淹涝胁迫条件下铵硝态氮混合处理(ANF)的叶片、总生物量以及硝态氮处理(NF)的根系、叶片和总生物量干重明显降低。淹涝胁迫降低3种氮形态处理叶片氮累积量,明显降低铵硝态氮混合处理和硝态氮处理植株氮、钾累积量,降低磷在铵硝态氮混合处理茎鞘、叶中的分配比例、磷在硝态氮处理根、叶中的分配比例以及钾在铵硝态氮混合处理茎鞘、叶中的分配比例。淹涝胁迫下铵态氮处理(AF)叶片含氮量、植株含钾量呈降低趋势;非淹涝胁迫下铵态氮处理(A)具有相对较高的植株氮、磷含量,且淹涝胁迫对氮、磷、钾在植株不同部位分配的影响相对较低。因此,本试验供应铵态氮苗期玉米具有相对较强的耐淹涝胁迫能力。     

根瘤菌和复合促生菌对大豆结瘤和生长的影响

为了研究不同根瘤菌和复合促生菌单独使用及复合后对大豆结瘤和生长的影响。采用大豆单独接种2种快生大豆根瘤菌、2种慢生大豆根瘤菌及根瘤菌分别与复合促生菌交叉接种,再种植的方法,观察大豆结瘤与生长情况。结果表明:(1)大豆结荚初期大豆快生和慢生根瘤菌处理的大豆地上部鲜重、地下部鲜重、结荚数、豆荚鲜重等生物学性状显著优于其它处理;快生根瘤菌处理的大豆结瘤率显著高于其它处理,慢生根瘤菌处理的总根瘤数和根瘤重量显著高于其它处理;(2)大豆结荚后期,对照处理的地上部鲜重、根鲜重显著高于其它处理,慢生根瘤菌和复合促生菌处理的根瘤数显著高于其它处理,快生根瘤菌剂处理的大豆粗蛋白含量显著高于其它处理,而复合促生菌处理的大豆产量显著高于其它处理。虽然快生根瘤菌两处理有利于地上部、地下部、有效根瘤数、土壤碱解氮的提升,但复合促生菌处理的大豆产量、土壤速效磷和土壤有效钾都显著高于其它处理,因此表明复合促生菌处理能增加大豆产量。     

Comparative Assessment of the Efficacy of Various Nitrogen Fertilizers

Summary

The efficiency of N fertilizers is usually poor; often less than 50% of the applied N is taken up by the crop. This review focuses on various N fertilizers with respect to the significance of different N loss pathways, namely (i) ammonia volatilization, (ii) dinitrogen and nitrogen oxide emissions, and (iii) nitrate leaching. Further, the significance of biological N immobilization, ammonium fixation and, finally, the impact of nitrate vs. ammonium uptake on crop yield are also discussed. The reviewed literature shows that N fertilizers may differ markedly in their susceptibility to losses. There is, however, considerable scope to improve N efficiency of each N source by proper N management practices.     

Studies on natural repellents against potato tuber moth (Phthorimaea operculella Zeller) in country stores

Summary The effects of the leaves of five plant species, one from each of the generaAmbrosia, Anemone, Eupatorium, Eucalyptus andLantana, on potato tuber moth were investigated under indigenous storage conditions at the Central Potato Research Station, Shillong (1800 m above sea level). Their action was compared with that of a biological insecticide (spores ofBacillus thuringiensis), a chemical insecticide (carbaryl), and an untreated control. The data collected after six months storage on tuber damage, sprout damage and the rotting indicated that the leaves ofLantana aculeata provided most protection to the tubers, reducing damage from over 70% in the check to below 5%, and sprout damage from over 45% to below 3%. Next best wasEucalyptus globulus followed byB. thuringiensis. They may be used on tubers stored for table use or for seed as they had no adverse effect on germination or on the yield of a subsequent crop.     

Mineral composition of some traditional Mexican teas

Teas of plant origin traditionally consumed by the Mountain Pima of Chihuahua, Mexico, were analyzed for mineral nutritional content. Fe, Cu, Zn, Ca, and Mg composition was determined for native teas made from shoots ofTagetes lucida, T. filifolia, Elytraria imbricata, andHolodiscus dumosus, and from root xylem ofCeanothus depressus andPhaseolus ritensis. Native uses of these teas are also described.     

Novel food and non-food uses for sorghum and millets

Sorghum and millets have considerable potential in foods and beverages. As they are gluten-free they are suitable for coeliacs. Sorghum is also a potentially important source of nutraceuticals such antioxidant phenolics and cholesterol-lowering waxes. Cakes, cookies, pasta, a parboiled rice-like product and snack foods have been successfully produced from sorghum and, in some cases, millets. Wheat-free sorghum or millet bread remains the main challenge. Additives such as native and pre-gelatinised starches, hydrocolloids, fat, egg and rye pentosans improve bread quality. However, specific volumes are lower than those for wheat bread or gluten-free breads based on pure starches, and in many cases, breads tend to stale faster. Lager and stout beers with sorghum are brewed commercially. Sorghum's high-starch gelatinisation temperature and low beta-amylase activity remain problems with regard to complete substitution of barley malt with sorghum malt . The role of the sorghum endosperm matrix protein and cell wall components in limiting extract is a research focus. Brewing with millets is still at an experimental stage. Sorghum could be important for bioethanol and other bio-industrial products. Bioethanol research has focused on improving the economics of the process through cultivar selection, method development for low-quality grain and pre-processing to recover valuable by-products. Potential by-products such as the kafirin prolamin proteins and the pericarp wax have potential as bioplastic films and coatings for foods, primarily due to their hydrophobicity.     

In vitro antimicrobial activity of different accessions ofSolanum commersonii Dun. from Uruguay

Summary The in vitro antimicrobial activity of extracts from accessions ofSolanum commersonii Dun. collected in the south of Uruguay was investigated against five microorganisms including the pathogenRalstonia solanacearum. A total of 30 extracts corresponding to organic and aqueous extracts were studied. Interestingly, most of the positive results for growth inhibition were againstR. solanacearum. The extracts were also analyzed for the presence of glycoalkaloids and lectins. Six of the ten aqueous extracts showed lectin presence and a wide variation in the type and amounts of glycoalkaloids, was found. Results indicate that there is no clear relationship between the antimicrobial activity against the five microorganisms screened and the presence or amounts of lectins and glycoalkaloids, traditionally regarded as possible antimicrobial metabolites in theSolanum genus, which indicates the presence of as yet unidentified antimicrobial compounds.     

Extreme resistance to infection by potato virus X in genotypes of wild tuber-bearingSolanum species

Summary Clones derived from thirty-one different accessions (nineteen of Argentine origin) belonging to eightSolanum species were screened for resistance to infection by potato virus X strain cp (PVX cp) by mechanical inoculation of plantlets that had been micropropagated in vitro. Estimates of PVX multiplication obtained by enzyme linked immunosorbent assay and slot blot nucleic acid hybridization allowed the identification of resistant clones derived from five accessions belonging toS. commersonii S. oplocense, S. sparsipilum andS. tuberosum andigena. Resistant genotypes supported PVX concentrations 5 to 15 times smaller than did the susceptible control cultivar Spunta. Graft inoculation test confirmed the presence of extreme resistance similar to that conferred by the ‘immunity’ gene X¹ (also called RX_act).     

Cyanobacteria Secondary Metabolites as Biotechnological Ingredients in Natural Anti-Aging Cosmetics: Potential to Overcome Hyperpigmentation,Loss of Skin Density and UV Radiation-Deleterious Effects

The loss of density and elasticity, the appearance of wrinkles and hyperpigmentation are among the first noticeable signs of skin aging. Beyond UV radiation and oxidative stress, matrix metalloproteinases (MMPs) assume a preponderant role in the process, since their deregulation results in the degradation of most extracellular matrix components. In this survey, four cyanobacteria strains were explored for their capacity to produce secondary metabolites with biotechnological potential for use in anti-aging formulations. Leptolyngbya boryana LEGE 15486 and Cephalothrix lacustris LEGE 15493 from freshwater ecosystems, and Leptolyngbya cf. ectocarpi LEGE 11479 and Nodosilinea nodulosa LEGE 06104 from marine habitats were sequentially extracted with acetone and water, and extracts were analyzed for their toxicity in cell lines with key roles in the skin context (HaCAT, 3T3L1, and hCMEC). The non-toxic extracts were chemically characterized in terms of proteins, carotenoids, phenols, and chlorophyll a, and their anti-aging potential was explored through their ability to scavenge the physiological free radical superoxide anion radical (O₂^•−), to reduce the activity of the MMPs elastase and hyaluronidase, to inhibit tyrosinase and thus avoid melanin production, and to block UV-B radiation (sun protection factor, SPF). Leptolyngbya species stood out for anti-aging purposes: L. boryana LEGE 15486 presented a remarkable SPF of 19 (at 200 µg/mL), being among the best species regarding O₂^•− scavenging, (IC₅₀ = 99.50 µg/mL) and also being able to inhibit tyrosinase (IC₂₅ = 784 µg/mL), proving to be promising against UV-induced skin-aging; L. ectocarpi LEGE 11479 was more efficient in inhibiting MMPs (hyaluronidase, IC₅₀ = 863 µg/mL; elastase, IC₅₀ = 391 µg/mL), thus being the choice to retard dermal density loss. Principal component analysis (PCA) of the data allowed the grouping of extracts into three groups, according to their chemical composition; the correlation of carotenoids and chlorophyll a with MMPs activity (p < 0.01), O₂^•− scavenging with phenolic compounds (p < 0.01), and phycocyanin and allophycocyanin with SPF, pointing to these compounds in particular as responsible for UV-B blockage. This original survey explores, for the first time, the biotechnological potential of these cyanobacteria strains in the field of skin aging, demonstrating the promising, innovative, and multifactorial nature of these microorganisms.     

Marine Pharmacology in 2009–2011: Marine Compounds with Antibacterial,Antidiabetic, Antifungal,Anti-Inflammatory,Antiprotozoal, Antituberculosis,and Antiviral Activities; Affecting the Immune and Nervous Systems,and other Miscellaneous Mechanisms of Action ?

The peer-reviewed marine pharmacology literature from 2009 to 2011 is presented in this review, following the format used in the 1998–2008 reviews of this series. The pharmacology of structurally-characterized compounds isolated from marine animals, algae, fungi and bacteria is discussed in a comprehensive manner. Antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral pharmacological activities were reported for 102 marine natural products. Additionally, 60 marine compounds were observed to affect the immune and nervous system as well as possess antidiabetic and anti-inflammatory effects. Finally, 68 marine metabolites were shown to interact with a variety of receptors and molecular targets, and thus will probably contribute to multiple pharmacological classes upon further mechanism of action studies. Marine pharmacology during 2009–2011 remained a global enterprise, with researchers from 35 countries, and the United States, contributing to the preclinical pharmacology of 262 marine compounds which are part of the preclinical pharmaceutical pipeline. Continued pharmacological research with marine natural products will contribute to enhance the marine pharmaceutical clinical pipeline, which in 2013 consisted of 17 marine natural products, analogs or derivatives targeting a limited number of disease categories.