当北极不再是北极

北极在许多人心中意味着遥远、寒冷和神秘，是一个冰天雪地的童话世界。然而，近年来气候变暖和油气田开发对北极带来了很大冲击，当地特有的景观、传统和生活方式随着冰雪的消融在慢慢发生变化。     

Carbendazim adsorption on montmorillonite, peat and soils

The adsorption of carbendazim by peat and montmorillonite was studied as a function of the exchangeable cations and temperature. The adsorption on soils was also studied. The kinetics of carbendazim adsorption on peat showed that adsorption equilibrium was reached within 1 h. The order of adsorption of carbendazim on peat was as follows: H⁺-peat > Cu²⁺-peat > Co²⁺-peat > Mg²⁺-peat > K⁺-peat, and the thermodynamic parameters appeared to suggest an adsorption mechanism involving hydrogen bonds, although in the H⁺, Cu²⁺ and Co²⁺ samples a protonation process and adsorption of the protonated species were also likely. The kinetics of carbendazim adsorption on montmorillonite (mont.) showed that equilibrium was reached within 1 h. The order of adsorption was: H⁺-mont. > Cu²⁺-mont. > Co²⁺-mont. > Ca²⁺-mont., the adsorption on the H⁺ and Cu²⁺ samples being much greater than that on the other samples. For the H⁺ and Cu²⁺ samples, the thermodynamic parameters appeared to suggest a double mechanism: physical adsorption, and protonation and adsorption by ion exchange. The most probable mechanism for the adsorption of carbendazim on the Co²⁺ and Ca²⁺ samples was physical bonding. The capacity for adsorption of this fungicide on soil was dependent on the organic matter, nitrogen and clay content, as well as on the cation exchange capacity. No significant correlation was found with pH, C/N ratio or free iron content.     

RELATIONSHIPS AMONG METALS IN THE SOLID PHASE OF SOILS AND IN WILD PLANTS

The relationships between plant and soil systems were investigated using multivariate statistical methods and relative ionic impulsions. Soil samples were taken from three locations and wild plant species consisted of:Poa, Pteridium aquilinum, Diplotaxis, Plantago lanceolata andTrifolium repens. The content of Mg, Ca, Na, K, Mn, Fe, Pb, Co, Ni, Cu, Zn and Cr in soils and plants was determined. A five-step chemical fractionation procedure (speciation) was applied to soil samples. Total metal contents were determined and amounts extracted with HCl, EDTA and DTPA were measured. Pb, Co, Ni, Cu, Fe, Zn, Cd and Cr in soils (considered as microconstituents for plants) show a greater number of statistically significant relationships with plant contents than those shown by macroconstituents (Mg, Ca, Na, K and Mn). On the other hand, only Zn and Pb extracted with EDTA and DTPA seem to be related to metal contents in wild plants. When using relative ionic impulsions, any soil fraction (obtained from the fractionation procedure, including the soluble fraction, which is the sum of all the fractions except the residual) is suitable for the study of soil-plant system, suggesting a global balance among all the fractions. Our results suggested an active assimilation for K and a passive uptake for Na, Ca and Mn. Furthermore, Fe seemed to favour the active assimilation of the other microelements.     

Gibberellic acid and fruit set in sweet orange

A single GA₃-spray at petal-fall to the entire tree enhanced initial set in the ‘Navelate’ sweet orange (Citrus sinensis L. Osbeck), but this effect was transient and in most cases final yield was not increased. When followed by girdling, final yield was increased even in the most productive orchards, this effect being due to an increase in fruit number while fruit size was unaffected. The response was markedly dependent on the GA₃ concentration, 5 mg l^?1 giving the best results. Higher concentrations up to 20 mg l^?1 even reduced yield compared to the untreated control trees. Chlormequat reduced the number of fruits finally cropped without affecting their size, an effect which may be explained through a reduction in the endogenous gibberellin levels.     

Nutrient cycling and greenhouse gas emissions from soil amended with biochar-manure mixtures

Integrating biochar into cattle diets has recently emerged as a potential management practice for improving on-farm productivity.Yet,information concerning the cycling of biochar-manure mixtures is scarce.A 70-d incubation experiment was conducted within two surface(0–15 cm)Mollisols with contrasting textures,i.e.,sandy clay loam(Raymond)and clayey(Lethbridge),to evaluate the effects of biochar(3 Mg ha^-1)on cumulative greenhouse gas(GHG)emissions and related fertility attributes in the presence or absence of cattle manure(120 Mg ha^-1).Five treatments were included:i)non-amended soil(control,CK),ii)soil amended with pinewood biochar(B),iii)soil amended with beef cattle manure(M)(manure from cattle on a control diet),iv)soil amended with biochar-manure(BM)(manure from cattle on a control diet,with pinewood biochar added at 20 g kg^-1of diet dry matter),and v)soil amended with B and M at the aforementioned rates(B+M).A total of 40 soil columns were prepared and incubated at 21℃and 60%–80%water-holding capacity.On average,total CO₂fluxes increased by 2.2-and 3.8-fold under manure treatments(i.e.,M,BM,and B+M),within Raymond and Lethbridge soils,respectively,relative to CK and B.Similarly,total CH4 fluxes were the highest(P<0.05)in Raymond soil under B+M and BM relative to CK and B,and in Lethbridge soil under M and BM relative to CK and B.In Lethbridge soil,application of BM increased cumulative N₂O emissions by 1.8-fold relative to CK.After 70-d incubation,amendment with BM increased(P<0.05)PO_4-P and NO_3-N+NH_4-N availability in Raymond and Lethbridge soils compared with B.A similar pattern was observed for water-extractable organic carbon in both soils,with BM augmenting(P<0.05)the occurrence of labile carbon over CK and B.It can be concluded that biochar,manure,and/or biochar-manure have contrasting short-term effects on the biogeochemistry of Mollisols.At relatively low application rates,biochar does not necessarily counterbalance manure-derived inputs.Although BM did not mitigate the flux of GHGs over M,biochar-manure has the potential to recycle soil nutrients in semiarid drylands.     

运用抗性基因同源序列标记快速进行水稻种质资源DNA指纹图谱分析

用2个抗性基因同源序列(RGA)引物分析了菲律宾国家水稻所水稻种质资源库中265个抗或感水稻东格鲁病(RTV)的种质资源的遗传差异。引物CLRR的分辨能力极高,共扩增出了48条多态带,平均每个品种28.6条。每个品种平均扩增出46.9条多态带。DNA指纹图谱分析结果表明,通过变性聚丙烯酰胺凝胶电泳,RGA引物能有效地分析群体材料在分子遗传上的差异,这说明RGA标记是水稻种质资源DNA指纹快速识别的理想选择。通过聚类分析还发现本研究的水稻品种间存在很大的遗传差异。     

Hormonal control of splitting in ‘Nova’ mandarin fruit

Fruit splitting, a physiological disorder of peel development in citrus, has been studied in terms of peel thickness and puncturing resistance in ‘Nova’ mandarins. Both features are negatively correlated with splitting. A mixture of G A, and 2,4-D reduced significantly the percentage of affected fruits. The best results were obtained with two applications at 60 and 30 d before the anticipated onset of the disorder. Calcium nitrate applications have similar effects, but were ineffective in orchards with a low natural incidence of splitting.     

Effect of field pea (Pisum sativum L.) level on intake,digestion, ruminal fermentation and in vitro gas production in sheep fed maintenance diets

The objective of this study was the characterization of the nutritive value, ruminal fermentation and nutrient digestibility of field pea (Pisum sativum L.) hay (FPH) by‐product through in situ, in vitro and in vivo tests. A FPH diet was administered ad libitum to four sheep (live weight (LW) 38.0 ± 2.0 kg) at four inclusion levels (0, 25, 50 and 75%) over a conventional sorghum grain/oat straw ration in a 4 × 4 Latin square design. The in situ degradability of FPH was 67% dry matter (DM), 71% crude protein and 66% neutral detergent fiber (NDF). The inclusion of FPH did not affect (P ≥ 0.05) the DM (61 ± 0.4 g/LW^0.75/day) and organic matter (OM) intake (56 ± 0.7 g/LW^0.75/day). Total DM digestibility (68 ± 2.5%), OM (70 ± 3%), and NDF (60 ± 3%), were not different (P ≥ 0.05) between control and FPH inclusion diets. The diet had no effect on ruminal pH, ruminal ammonia concentration, total and individual volatile fatty acids. The chemical composition and sheep intake behavior indicate that FPH by‐product is medium quality forage when incorporated in maintenance rations.     

初榨橄榄油中多酚化合物的UPLC-FLD检测及其抗氧化活性研究

采用超高效液相色谱荧光检测法(UPLC-FLD)检测不同品种初榨橄榄油中6种多酚化合物的含量,并测定样品的总多酚含量及抗氧化活性,同时对多酚组分与抗氧化能力的相关性进行分析。结果表明:色谱条件为采用Cadenza色谱柱(150 mm×4.6 mm, 5 μm),柱温35 ℃,以0.1%甲酸-水(A)-乙腈(B)为流动相进行梯度洗脱,荧光光谱激发波长为278 nm,发射波长为339 nm。在此条件下,初榨橄榄油样品中6种多酚化合物可在17 min内得到较好分离,并在较宽的浓度范围内呈良好的线性关系(R²≥ 0.999 5),且精密度高,日内精密度相对标准偏差(RSD)≤ 4.91%,日间精密度RSD ≤5.41%,加标回收结果准确可靠,平均回收率93.42%~119.86%,RSD ≤ 6.26%。不同初榨橄榄油样品中羟基酪醇、酪醇、香草酸、松脂酚及总多酚含量差异较大,而橄榄苦苷和女贞苷含量最低,且样品间差异较小。初榨橄榄油多酚提取物具有良好的抗氧化活性,但不同品种间具有较大差异,ABTS法测定的总抗氧化能力为0.95~2.71 mmol·L^-1 Trolox,DPPH自由基清除率为7.22%~66.23%,抑制羟自由基能力为13.24~136.06 U·mL^-1,其中Coratina的抗氧化活性最强,总多酚含量与提取物总抗氧化能力呈显著正相关。