稻田春玉米氮、磷、钾配方施肥数学模型的初步研究

采用氮、磷、钾三因素旋转组合设计,通过计算机模拟寻优,建立了稻田春玉米--杂交晚稻种植制度中玉米产量--施肥量,玉米生产利润--施肥量数学模型:分析了氮(X₁)、磷(X₂)、钾(X₃)的主效应及交互效应与产量的关系,它们对产量的影响为氮＞钾＞磷.筛选出玉米产量≥8250kg/hm²的最优方案为:N394.96～401.25kg/hm²、P₂O₅116.99～121.8kg/hm²、K₂O 232.29～237.06kg/hm²,其比例为N∶P₂O₅K₂O=3.4∶1∶2.并筛选出玉米利润≥6800元/hm²的最优方案为:N380.60～385.55kg/hm²,P₂O₅104.73～108.03kg/hm²、K₂O222.20～225.12kg/hm².其比例为N∶P₂O₅K₂O=3.6∶1∶2.1。     

内单4号春玉米高产栽培技术的研究

以内单4号春玉米为试验材料,采用五因素二次通用回归旋转组合设计(1/2)实施方案,通过建立相应的产量模型,系统地研究了主要栽培因素对产量的影响。试验表明,在当地生产条件下,内单4号公顷产量11250kg的优化栽培措施为:密度6.885～7.065万株/hm²,种肥N 30kg/hm²,种肥P₂O₅96.75～108.15kg/hm²,种肥K₂O 66.75～74.4kg/hm²,拔节肥N 131.85～145.65kg/hm²,穗肥N102.0～117.3kg/hm²;产量构成为:公顷穗数(68250±750),穗粒数(505±10),百粒重(34.8±0.5)g。     

钾肥对玉米的增产增收效果与利用率

田间试验结果表明,钾对玉米有较显著的增产作用。以施用K₂O 50～100kg/hm²可以获得最大产量和最高收益。钾肥在风沙土上增产、增收效果好于淡黑钙土和黑土,在黑钙土上好于黑土。施钾量与玉米产量关系式为y=a+bx+cx²。土壤有效钾含量与施钾最大增产量呈极显著的直线负相关y=3491.5-23.00x。玉米施钾可提高植株和子粒含钾量和干物质产量,因而明显提高吸钾量。在中肥力黑土上施用100kg/hm²钾(K₂O)的利用率为37.56%。     

吉林省不同类型土壤玉米施肥效应研究

吉林省东、中、西不同类型土壤田间试验结果表明:不同类型土壤的氮、磷、钾肥施用模式符合二次曲线Y=ax²+bx+c。利用该模式,结合肥料和玉米价格进行综合分析,明确了不同类型土壤上的氮、磷、钾施用效益,即东部冲积土玉米最佳施肥量为N192kg/hm²、P2O556kg/hm²、K₂O33kg/hm²;中部黑土玉米最佳施肥量为N133kg/hm²、P₂O₅38kg/hm²、K₂O47kg/hm²;西部淡黑钙土玉米最佳施肥量为N59kg/hm²、P₂O₅65kg/hm²、K₂O51kg/hm²。     

锦科杂1号高产优质施肥模型的研究

 利用“3414”回归设计方案对锦科杂1号高产优质栽培施肥用量进行试验,对试验结果进行统计建模,建立了以子棉产量为目标函数的氮、磷、钾三因素肥料效应模型.经模拟仿真因素取值和统计分析,得出子棉产量3982.11～4015.17 kg·hm^-2的施肥量的95%置信区间分别为纯氮311.91～328.73 kg·hm^-2,P₂O₅ 151.87～162.33 kg·hm^-2,K₂O 238.88～255.86 kg·hm^-2。并对两因素互作效应及单因素效应进行了剖析。通过对氮磷钾、氮磷、氮钾、磷钾及氮、磷、钾三类7种模型提供的施肥量和期望产量进行经济效益分析,据此提出锦科杂1号高产优质高效栽培的推荐施肥措施：每公顷施纯氮300 kg,P₂O₅ 145.53 kg,K₂O 232.85 kg,产量期望为4029.42 kg·hm^-2,产投比12.57。     

主要栽培措施对中单808产量的影响

大田条件下,研究了种植密度、施氮量、施氮方式、喷施植物生长调节剂（玉黄金）等主要栽培措施对玉米新品种中单808产量的影响。结果表明：中单808高产适宜种植密度为45 000株/hm²,氮肥合理施用量为施纯氮225 kg/hm²,施用方式为播种前、拔节中期分两次按60∶40比例施入;喷施玉黄金对中单808产量形成具有明显效应,适宜喷施时期为14展叶期,喷施量为产品推荐量的1/2,增产效果显著。     

套种玉米高产施肥指标的研究与生产实践

通过研究确立了套种玉米施肥与产量的二元二次回归模型，模型经方差分析F值达极显著水平。进一步分析，该研究的三个主放因子对量的影响大小程度是氮＞磷＞钾，其相关程度为0.93。经过模拟寻优，玉米单产9000－9750kg/hm²的N、P、K施量的优化组合是：玉米施氮360kg／hm²，施P₂O₅69.8kg/hm²，施K₂062.7kg/hm²。该施肥指标通过大面积生产示范验证，玉米平均产量在940－9600kg/hm²，比常规栽培田玉米产量7411.5kg/hm²，增产1993.5－2188.5kg/hm²，增产历26.9%－29.5%。增产效果显著。生产示范产量接近目标产量，说明该方程可以为大田预测，研究所得的施肥指标可以作为小麦套种玉米高产施肥的依据。     

半干旱地区玉米高产栽培经济施氮量研究

2005～2006年在半干旱区玉米高产田上进行了氮肥经济用量研究。结果表明:玉米最高产量施N量为143.5～145.0 kg/hm²,经济产量施N量为98.2～111.7 kg/hm²;经济施N比不施氮肥增产8.01%～12.89%;经济施N比最高产量施N节约用N量31.8～46.8 kg/hm²。     

氮、磷、钾和密度等因素对玉米产量形成的作用

采用回归正交旋转组合设计的方法,研究影响玉米产量的N、P₂O₅、K₂O三要素施肥量及种植密度,并对各因素的单独反应规律及其互作效应进行探讨。结果表明种植密度和施N量是制约玉米产量的主导因素,单产6000kg/hm²以上农艺措施为:公顷施纯N 240.6～266.4kg、P₂O₅106.75～121.4kg、K₂O 206.6～238.2 kg及公顷留苗52560～55440株。     

吉林中部玉米高产施肥与提高化肥利用率研究

通过两年的试验研究结果表明:应用现代高产施肥技术比当地大田玉米增产40%～115%,抗灾能力较强,年际间的产量变异较小;高产与经济效益协调统一的化肥施用量,N素为255kg/hm²较合理,而配施P₂O₅90kg/hm²,K₂O 135kg/hm²产量较高,同时N肥利用率可以从目前的30%左右提高到40%以上,土壤残留N较少,环境负荷小。     

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.     

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.