不同耕作方式对土壤环境及玉米产量与效益的影响

通过免耕(MF)、传统旋耕(CK)、深松+旋耕(SS)和深松深施肥+旋耕(SF)4种耕作处理方法,对比研究不同耕作方式对土壤环境、玉米根系分布、产量及经济效益的影响。结果表明,SS处理较CK和MF处理能够降低土壤紧实度,在0～40 cm土层,土壤紧实度由9 948.1 kPa降低到909.8 kPa,土壤容重从2.31 g/cm~3降到1.28 g/cm~3;在41～60 cm土层中,SS处理根系占总根重的23.55%以上,增加农田30 cm深层土壤中的总根量。玉米产量由高到低依次为SFSSCKMF处理,最大产量2019年为15 517.8 kg/hm~2。SS和SF处理比CK处理分别增加净收益20.16%和12.54%,单位产出效益显著高于CK(P0.05);MF处理净利润较CK降低了24.93%。研究结果表明,深松耕作可有效打破土壤犁底层,增加深层土壤养分,提高作物产量,增加效益。     

窄行密植对高产春大豆根系生长的影响

大田条件下研究了黑农41在两种密度（45万株/hm^2、60万株/hm^2）分别在三种行距（20cm、30 cm、40 cm）下对大豆根系生长的影响。结果表明,在相同行距条件下,高密度明显降低单位面积根系干重,主要是外环（1/4行距-1/2行距）深层根量减少,地上部生长受抑制,根冠比明显增大,根系伤流量和根系还原力明显降低;在相同密度下,合理株行距配置增加单位面积根干重,主要增加外环根量,进而促进地上部生长,降低根冠比,提高根系伤流量和根系还原力;较窄的行距使高密度大豆根系在水平方向分布趋于均匀,并增加外环深层根量。密度对根系生长的影响明显大于株行距配置。产量为5063.90 kg/hm^2,R5期根系干重为220.0 g/m^2,外环根干重占总根干重19%,20～50 cm深层根干重占总干重32.1%,根冠比0.17;R4期单位面积根系伤流量为15.98g/m^2.h。     

吉林省西部半干旱区深松蓄水耕作技术研究

深松可以提高土壤含水量2～3个百分点,使耕层土壤松紧度趋于一致,具有改善土壤结构的作用,有利于玉米根系向深层伸展,20～40cm耕层的玉米根重增加19%以上,玉米产量提高10%。深松的第二年仍有一定的蓄水增产效果。条带深松平作蓄水效果更明显。     

生物炭对玉米根系特性及产量的影响

采用大田试验研究生物炭对郑单958产量和不同生育时期根系生长、形态特征及生理特性的影响,明确生物炭对玉米根系与产量的效应,探明生物炭在玉米生产上应用的潜力与价值。结果表明,土壤中施入生物炭能增加玉米根系的总根长、根体积和根干重,提高玉米根系总吸收面积和活跃吸收面积。在玉米生育后期,生物炭在一定程度上延缓了根系衰老,成熟期施生物炭处理根系活力分别比对照高48.12%和42.71%;同时维持了较为适宜的根冠比,根系生理功能增强;添加生物炭后郑单958最高产量达12 076.35 kg/hm2,比对照增产10.23%,具体表现为穗长、穗行数、行粒数和百粒重的提高。     

深松及氮肥深施对超高产春玉米根系生长、产量及氮肥利用效率的影响

以内单314为材料,研究深松及氮肥深施对超高产春玉米生育后期根系生长、产量及氮肥利用效率的影响.结果表明,随着散粉后生育进程的推进,玉米单株根重、根系体积逐渐下降,且在同一生育期表现出随土层深度加深呈递减的趋势.0～ 60 cm土层单株根系表面积自散粉期开始呈先升后降的变化趋势,峰值出现在灌浆期.各处理根系活力随土层深度的增加总体上表现为先升高后下降的变化趋势,随着散粉后生育进程的推进,根系活力的峰值出现下移.深松30 cm根重、根系体积及根表面积明显增加,根系活力显著提高;深松30 cm及氮肥深施15 cm可促使根系下移,明显提高深层根系特别是20 ～ 40 cm根系活力及比重.     

玉米追肥方法的研究

本文通过追肥方法试验,系统研究了不同追肥方法对玉米产量与肥效、玉米根系生长与分布、土壤中氨挥发损失及肥料利用率等方面的影响.结果表明:玉米垄沟深追肥土壤中氨挥发少,肥料利用率高,玉米根系分布广,下扎得深且须根多,既能增强玉米吸肥吸水能力,又能增强玉米耐旱抗倒伏能力,达到增产增收.此外,玉米垄沟深追肥省工省力,追肥均匀,简便易行,是一项高产、节能、高效的技术措施.     

秸秆深层还田对玉米根系及产量的影响

针对辽西地区土壤耕层变浅和秸秆浅旋还田造成的土壤漏风跑墒等问题,实施秸秆机械化深层还田与常规耕作(CK)对比试验,测定玉米根系生长状况。结果表明,秸秆深层还田能够增强玉米扎根性能,扩展根系分布空间,扎根深度增加5～10 cm,根系分布空间扩大6000(初生节根)～154500(次生根)cm3;秸秆深层还田的次生根数目明显高于CK,且CK根系主要分布在10～20 cm土层深度,秸秆深松还田处理根系则集中分布在21～30 cm土层深度;秸秆深层还田处理与CK相比玉米产量提高18.16%,差异显著。     

深松条件下春玉米花后衰老过程中根系生物学变化特征

采用PVC管栽方法,研究模拟犁底层和深松处理下春玉米花后衰老过程中根系的生物学变化特征。结果表明,在玉米花后,相同根层节根数均表现为深松处理>模拟犁底层处理。犁底层影响根系在不同深度土壤空间分布,深松处理20～35 cm 土壤深度和36～75 cm 土壤深度玉米根系体积分别比犁底层处理增加176.33%和185.92%;在模拟犁底层处理下,90%以上的根系主要集中在0～20 cm土壤深度,深松处理90%以上的根系主要集中分布在0～35 cm深度土壤。深松增加下层土壤（30～75 cm）根系比重,根系空间分布更加合理。根系衰老进程,花后20 d开始犁底层处理下36～75 cm土壤深度玉米根系衰老速度加快,该深度根系重量开花期比深松处理低2.91%,花后50 d比深松处理低12.31%。犁底层的存在限制玉米根系的发育,深松有利于增加深层土壤的根系分布,能减缓后期根系衰老速度。     

耕作方式对玉米根系构型及抗根倒伏能力的影响

通过云南典型的红壤坡耕地对土壤实施深松+旋耕15 cm(SRT)、深松+免耕(SNT)、深松+翻耕20 cm(SP1)、深松+翻耕30 cm(SP2)、旋耕15 cm(RT)、免耕(NT)、翻耕20 cm(P1)和翻耕30 cm(P2)8种耕作方式,研究对玉米的根系根条数、根直径、入土角度、根幅、生物量及根系抗拔力等的影响。结果表明,深松+翻耕20 cm处理能增加玉米根条数、根系入土角度和10 cm土层处根系生长幅度,增大根系生物量,尤其是深层土壤(20～30 cm)根系生物量,同时对玉米产量也具有提高作用。深松+翻耕30 cm处理能增大根系的垂直抗拔力。因此,土壤通过深耕处理能改善玉米根系构型和分布,进而增强玉米根系抗倒伏能力。     

南方丘陵红壤旱地不同施肥模式对春玉米生物学特性及产量的影响

以当地常规施肥模式(CK)为对照,研究南方丘陵红壤旱地不同施肥模式(CO:常规施肥+有机肥;CB,常规施肥+生物有机肥;CP:常规施肥+钾肥)对春玉米生物学特性及产量的影响。结果表明,单株叶面积和叶面积指数大小顺序为CO>CP>CB>CK处理,全生育期单株叶面积和叶面积指数均显著高于对照,抽雄期和成熟期CO和CP处理均显著高于其他处理。拔节期、抽雄期和成熟期CO和CP处理植株根系干重、茎干重均显著高于其他处理,CO处理植株叶干重显著高于对照。CO处理穗长显著高于对照;CP处理行粒数、穗粒数和百粒重均显著高于对照。CO、CB和CP处理产量分别比对照增加19.36%、13.08%和22.10%,增产原因主要是行粒数、穗粒数和百粒重的增加。     

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.     

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.     

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.     

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.     

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.     

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.