东北玉米耕作制度存在的主要问题与新型耕作制度展望

东北是中国重要的商品粮生产基地，对确保国家粮食安全具有重要的战略意义。长期“重用轻养”的利用方式导致土壤严重退化，生产能力下降，如何实现东北黑土保护性利用是当前农业领域研究热点。玉米是东北第一大粮食作物，长期传统耕作制度不仅加速土壤退化，同时导致玉米秸秆“过剩”。因此，如何通过耕作制度改革来解决东北现行耕作制度中存在的主要问题已迫在眉睫。本文从土壤结构、土壤肥力、土壤侵蚀和秸秆还田4个方面总结传统耕作制度存在的主要问题，分析主要新型耕作制度模式的优缺点，最后展望东北耕作制度发展方向，为黑土地保护和国家粮食安全提供借鉴。     

早春地膜双季青贮玉米物质生产及其资源生产效率的研究

针对两熟农业区畜牧业发展对青贮玉米需求不断增加,在两熟热量限制的北京地区建立了双季青贮玉米的新型生产技术模式,通过采取早春季节的地膜覆盖技术研究了双季青贮玉米物质生产与资源生产效率。结果表明,早春地膜栽培技术提高了青贮玉米鲜产量15.6%,物质生产提高29.9%;早春季节地膜在当季提高温度生产率、光照生产效率、水分生产效率均达30%以上,全年平均在15%左右。早春地膜是提高双季青贮玉米高产高效的有效技术途径。     

西南区突破性高产玉米品种育种思考

西南区是中国玉米主产区之一,该区域突破性品种少,自然灾害频繁,单产不高、总产不足。只有不断选育出适应西南生态和生产条件的突破性高产、优质、玉米杂交种推广应用,才能迅速提高西南区玉米单产和总产,满足经济发展对玉米的需求。全面分析西南区玉米育种面临的主要问题;对今后的玉米突破性育种目标和技术发展方向等进行了阐述。     

土壤耕作制度对玉米和大豆田间杂草种群的影响

土壤耕作制度对玉米和大豆田间杂草种群的影响Ｄ．Ｄ．Ｂｕｈｌｅｒ耕地杂草群落的种类组成和密度大小反映了农艺措施的特点。玉米和大豆生产中逐渐减少土壤耕作，改变了杂草防治、生存及繁殖的环境。从每年进行全面土壤翻耕改变为减少土壤翻耕的土壤耕作制度，导致了杂草...     

浅议我国玉米育种工作的限制因素及解决方法

在今后的几十年,我国玉米需求面临巨大的压力,育种目标的核心是继续提高杂交种的生产潜力和利用价值。但品种资源的狭窄制约我国生产水平的提高。因此为了实现玉米生产的可持续以展,拓宽品种资源,加强对种质的改良、扩增、创新是当务之急。玉米种质产业的发展要在种质扩增、改善品质和应用生物技术领域取得突破性进展。     

花生应用化调技术的现状及设想

花生是我国四大主要食用油料作物之一。近年来,由于粮油争地争季节矛盾和耕作制度的调整,花生面积逐年缩减,为了满足社会需求日益增长的需要,必须在稳定和恢复花生面积的基础上提高单产。应用化调技术可使花生朝着人们期望的方向发展,即营养与生殖、地上与地下生长关系协调,经济系数提高,最终为提高单产提供可能性。因此,深入研究化调技术在花生上的应用,对提高单产,满足社会对油料的需求具有重要意义。     

山区农业结构调整中的玉米发展战略

玉米生产是山区粮食生产的中流砥柱.在目前生产条件差、自然灾害频繁、粮食生产能力弱的情况下,要满足社会对粮食生产多层次、多样化的需求,以玉米为重点的粮食生产在结构调整中面临着提高单产与提高品质的双重压力,任务极其艰难.因此,发展山区粮食生产的基本思路是:一立足两围绕三转变四提高五优化”,其主要措施:保证基本面积,大抓农田改造,推广高优品种,开发特用玉米,狠抓关键技术,加强科学试验,促进农民参与,走产业化之路。     

陕西关中西部玉米品种更新换代演变史

回顾陕西关中西部玉米品种6次大的更新换代演变史,可以明显看出每更新一代玉米品种,对产量与品质都带来显著的提高,并对耕作制度改革带来明显的改进,更对农机、化肥、涉农工业带来较大的促进与发展。一部品种换代演变史,就是一部农业科技发展史。本文旨在为今后陕西关中西部玉米品种选育、推广、更新换代提供翔实的划分参考依据。     

浅析发展高赖氨酸玉米对今后玉米产业的影响

着重分析我国玉米生产和玉米育种面临的任务和存在的问题。随着农业生产的发展,玉米的主要用途依次是饲用、食用和工业用。目前我国玉米65%~70%用于饲料,人均占有饲用玉米60 kg,美国人均占有饲用玉米300~500 kg,而我国远远低于农牧业发达国家。中国人口众多,再经过30年努力,玉米总产翻一番,人均占有玉米量也不超过120 kg,仅靠玉米数量增加是无法满足畜牧业发展对饲料的需求,因为大部分肉、禽、蛋、奶是靠玉米转化的。当前应加强品质育种研究,使今后玉米产业向高层次迈进,发展优质蛋白玉米(高赖氨酸玉米opaque-2玉米)是一项势在必行的农业技术措施。此外,为满足市场需求,还要发展高油玉米、青饲青贮玉米、高直链淀粉玉米等。     

江苏沿海旱粮棉区棉花玉米间作种植制度的评价与展望

江苏省粮棉间作面积近年来每年在470万亩上下,占棉田铺地面积38.5%,是面积最大的一种耕作制度。但从十多年来的发展历史看,年度之间棉花产量不稳定,为了本棉区粮棉生产的进一步发展和提高,对这种耕作制度就我们所做调查研究进行一些分析     

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.