Determination of free amino acids in burley tobacco by high performance liquid chromatography

A reversed-phase high performance liquid chromatographic method was developed for determining free amino acids in burley tobacco. The test was done by OPA/3-mercaptopropionic acid as the pre-column derivatizing reagent. Chromatographic column was Elitte C¹⁸ column (4.6 mm × 250 mm i.d., 5 μm). Mobile phase A was 18 mol/l NaAc (pH7.2) including 0.002%(v/v) triethylamine and 0.3%(v/v) furanidine. Mobile phase B was 100 mol/l NaAc (pH7.2)–acetonitrile–methanol (v/v = 1:2:2). The column temperature was 40 °C and the flow rate was 1.0 ml/min. The fluorescence detector was used with 350 nm excitation wave length and 450 nm emission wave length. The average recoveries of the method ranged from 95.3–100.7% with the relative standard deviation of 2.32–9.24%. The method is simple, accurate and has good repeatability. The results of the determination of seventeen kinds of free amino acids in burley leaves were produced by the way of different ratios of cake fertilizer and inorganic fertilizer. The results show that Aspartic acid has the highest content however ratio of cake fertilizer and inorganic fertilizer. The contents of most of the free amino acids are increased and then gradually decreased with the increase in organic manure. The contents of most of the free amino acids are very close at 15:85% ratio and 30:70% ratio of cake fertilizer and inorganic fertilizer. The total amount of free amino acids is the highest at 30:70% ratio of cake fertilizer and inorganic fertilizer. Considering comprehensively, the quality of burley leaves is the best at 30:70% ratio of cake fertilizer and inorganic fertilizer.     

生物炭影响作物生长及其与化肥混施的增效机制研究进展

利用秸秆型生物炭进行还田改土不仅具有提升作物产量的潜力,而且能够产生明显的环境效益,现已成为当今国内外农业领域的研究热点.本文综述了近年来国内外有关生物炭添加影响作物生长的分子调控机制研究,尤其关注了生物炭与作物根系的互作效应;介绍了生物炭与化肥混施的生物学效应及可能的增效机制;展望了今后的研究方向,以期促进我国相关领域的研究.国内外的最新研究表明:生物炭土壤添加改善植物生长的关键是生长素相关信号转导分子,通过促进植物细胞扩增、细胞壁松弛、水及营养的转运等相关基因的表达,有利于植物的新陈代谢及生长.生物炭及其与根系的相互作用能够直接或间接地影响土壤物理、化学、生物因子,从而在炭、肥互作增效过程中起主导调控作用.     

氮肥运筹对小麦产量、氮素利用效率和光能利用率的影响

连续2年在西南冬麦区的重庆、仁寿、广汉、西昌4个地点,开展3种施氮水平(每公顷纯氮0、120、180 kg,简写为N₀、N₁₂₀、N₁₈₀)和3种氮肥分配模式(N_A:底肥100%;N_B:底肥70%+苗肥30%;N_C:底肥60%+拔节肥40%)的田间试验,监测小麦花后冠层叶片SPAD值、群体光合速率(CAP)、光能利用等生理参数和籽粒产量,计算氮素利用效率、光能利用率等.结果表明: 随施氮水平增加,小麦上三叶SPAD值、CAP、光合有效辐射(PAR)截获率和产量均呈增加趋势,而氮肥农学利用效率、生产效率、吸收效率和利用效率呈降低趋势.氮肥后移的增效作用因施氮水平而异,SPAD于N₁₈₀增效明显,而CAP于N₁₂₀增效明显,不同氮肥管理模式的光能利用率因地点而异.氮肥后移能明显提高小麦氮肥农学效率、生产效率、吸收效率和氮素表观回收率,但氮肥利用效率则略有减少.氮肥后移效果N_C总体优于N_B处理.不同地点比较,广汉的SPAD值、CAP、PAR截获率、氮肥利用参数较高,其产量也相应最高;西昌的产量、SPAD值及氮素利用效率较高,但其光能利用率和CAP较低;重庆和仁寿的SPAD值、光能利用率及氮素利用效率均较低,其产量也最低.小麦生物产量与各地点的籽粒产量、CAP、SPAD值和PAR累积截获量均呈显著或极显著的正相关关系.表明不同生态区域增施氮肥都能促进小麦增产,氮肥后移可进一步优化产量结构、改善氮肥和光能利用效率,但存在年份和地点差异,各地需要制定有针对性的氮肥管理模式.     

Performance and efficiency of a yeast biofilter for the treatment of a Nigerian fertilizer plant effluent

A biofilter composed of yeasts and cassava peel was used to detoxify fertilizer plant effluent. The biological oxygen demand was reduced on treatment from a range of 1200–1400 mg/l to a range 135–404 mg/l. The ammonia-nitrogen (NH₃–N) and nitrate-nitrogen (NO₃–N) were reduced after treatment from 1000 to 10 mg/l and from 100 to 17.6 mg/l, respectively. The biofilter is simple and easy to handle with high efficiency of 98%.     

An evaluation of carbon disulphide as a sulphur fertilizer and as a nitrification inhibitor

There was little release of extractable SO₄-S during four weeks from CS₂ applied by injecting into two S-deficient soils. In this incubation experiment, the rate of CS₂ was 30 μg S g⁻, placement was injection at 9 cm depth, soil temperature was 20°C, and soil moisture tension was 33 kPa. The yield of barley forage after seven weeks in the greenhouse showed only small increases from 10 or 30 μg S g⁻¹ of CS₂ as compared to Na₂SO₄, on the two soils. While CS₂ supplied little plant available S in the short term, it was an effective inhibitor of nitrification. In the laboratory, or in the field, the injection of CS₂ (with N fertilizers) at a point 9 cm into the soils either stopped or reduced nitrification. In one laboratory experiment, 35 μg of CS₂ g⁻¹ of soil with urea reduced nitrification for at least four weeks; and in another experiment 20 μg of CS₂ g⁻¹ of soil with aqua NH₃ nearly or completely inhibited nitrification at 20 days. In two field experiments, 3 and 12 μg of CS₂ g⁻¹ of soil (or 6 and 24 kg ha⁻¹) with aqua NH₃ inhibited nitrification from October to the subsequent May. In addition, CS₂ reduced the amount of ammonium produced from the soil N, both in these two field experiments and in the laboratory experiments. That is to say, CS₂ injected at a point, inhibited both nitrification and ammonification. In other field experiments, CS₂ at a rate of 10 kg ha⁻¹ was injected in bands 9 cm deep with urea in October, and by May there was still reduced nitrification. Less than half of the fall-applied urea alone was recovered as mineral N, but with the application of CS₂ the recovery was increased to three-quarters. The yield and N uptake of barley grain was increased where fall-applied banded urea or aqua NH₃ received banded CS₂, (NH₄)₂CS₃, or K₂CS₃. The average increase in yield from fall-applied fertilizer, from inhibitor with fall-applied fertilizer, and from spring-applied fertilizer was 800, 1370, and 1900 kg ha⁻¹, respectively. In the same order, the apparent % recovery of fertilizer N in grain was 24, 42, and 60.     

Nonlinear response of nitric oxide fluxes to fertilizer inputs and the impacts of agricultural intensification on tropospheric ozone pollution in Kenya

Crop yields in sub‐Saharan Africa remain stagnant at 1 ton ha^?1, and 260 million people lack access to adequate food resources. Order‐of‐magnitude increases in fertilizer use are seen as a critical step in attaining food security. This increase represents an unprecedented input of nitrogen (N) to African ecosystems and will likely be accompanied by increased soil emissions of nitric oxide (NO). NO is a precursor to tropospheric ozone, an air pollutant and greenhouse gas. Emissions of NO from soils occur primarily during denitrification and nitrification, and N input rates are a key determinant of emission rates. We established experimental maize plots in western Kenya to allow us to quantify the response function relating NO flux to N input rate during the main 2011 and 2012 growing seasons. NO emissions followed a sigmoid response to fertilizer inputs and have emission factors under 1% for the roughly two‐month measurement period in each year, although linear and step relationships could not be excluded in 2011. At fertilization rates above 100 kg N ha^?1, NO emissions increased without a concomitant increase in yields. We used the geos‐chem chemical transport model to evaluate local impacts of increased NO emissions on tropospheric ozone concentrations. Mean 4‐hour afternoon tropospheric ozone concentrations in Western Kenya increased by up to roughly 2.63 ppbv under fertilization rates of 150 kg N ha^?1 or higher. Using AOT40, a metric for assessing crop damage from ozone, we find that the increased ozone concentrations result in an increase in AOT40 exposure of approximately 110 ppbh for inputs of 150 kg N ha^?1 during the March–April–May crop growing season, compared with unfertilized simulations, with negligible impacts on crop productivity. Our results suggest that it may be possible to manage Kenyan agricultural systems for high yields while avoiding substantial impacts on air quality.     

Leaching losses of nitrogen from a clay soil under grass and cereal crops in Finland

Summary A 16-plot experimental field was established in 1975 on a clay soil in Jokioinen, Finland. The water discharge through tile drains was measured and its ammonium and nitrate N contents determined for each plot separately. The surface runoff was also measured and analysed. The annual runoff and the N leached from the surface of moderately fertilized (100 kg/ha/y N) cereal plots varied during 1976–1982 from 21 to 301 mm and from 2 to 7 kg/ha, respectively. The discharge of water and leaching of N through subdrains varied from 65 to 225 mm and from 1 to 38 kg/ha, respectively. The highest leaching was probably caused by a previous fallow. The annual N uptake by the crop varied between 41 and 122 kg/ha.Of the fertilizer-N used for cereals, 20% of that applied in the autumn was lost, but only 1 to 4 per cent was lost when applied in the spring. There was much less N leaching from ley than from barley plots, although the former was given twice as much N. The rate of N fertilization had only a very slight effect on N leaching from both ley and barley plots.The results were compared with those obtained in lysimeters filled with clay, silt, sand and peat soils. No definite conclusions can be drawn because the lysimeter experimental data are only for the first year.     

不同海拔地区种植的水稻次库碳水化合物含量的比较

在品种、土壤、底肥和追肥等一致的情况下,对三个不同海拔地区种植的水稻的次库(茎+叶鞘)中碳水化合物含量作了比较,结果表明:齐穗和黄熟期次库中总糖或淀粉含量均随海拔增高而增加。但在黄熟期,高海拔地区次库的总糖或淀粉含量比齐穗期的增加,而低海拔地区次库的总糖或淀粉含量则比齐穗期的降低。 齐穗期时,次库的淀粉含量随施用的氮素肥量的增加而降低。在黄熟期,温凉稻作区水稻次库的淀粉含量均随氮素底肥施用量的增加而增加,低熟地区水稻次库的淀粉含量则趋于一致,不过不同地区相比各处理次库的淀粉含量均因海拔增高而增加。 不同时期的氮素追肥使齐穗期次库淀粉含量因追肥时间推迟而增加,唯元江晚穗肥处理的低于中穗肥处理的。黄熟期因追肥时间提早而次库的淀粉含量增加,但元江以早穗肥处理的次库淀粉含量最低。与齐穗期相比时,低海拔地区的各个处理,其次库的淀粉含量均减低,但高海拔的昆明温凉稻作区,施早和中穗肥的水稻,在黄熟期次库的淀粉含量反而增高。还可以看出水稻种植地海拔越高,其次库淀粉含量对追肥时间越敏感。 基于水稻次库中淀粉含量对氮素肥料的反应,就三地气候条件讨论了上述的差异。     

Effect of continuous application of manures and fertilizers on rhizosphere microflora in arecanut palm

Summary The rhizosphere microflora of arecanut palm under continuous application of organic manures and inorganic fertilizers was studied. The nutrients applied are 100 g N, 40 g P₂O₅ and 140 g K₂O/palm/year in the form of organics and inorganics. The application of organic manure increased the microbial population. The increase in microbial population was observed between the rhizosphere samples collected at 0–30cm and 30–60 cm depths. The surface cultivation of soil increased the microbial population.Trichoderma sp. andAspergillus sp. dominated in therhizosphere of arecanut palm. Contribution No. 208. Central Plantation Crops Research Institute, Vittal-574243, Karnataka, India.