施肥对山地红枣林土壤微生物区系及酶活性的影响

采用田间试验与室内分析方法,研究施肥对山地红枣林土壤微生物区系及酶活性的影响。结果表明,施肥显著提高不同土层(0～20cm、20～40cm和40～60cm)中土壤微生物数量和酶活性(P<0.05),单一施肥与氮磷钾配施对土壤微生物区系和酶活性的影响有显著差异(P<0.05)。红枣林在施肥处理下土壤细菌、放线菌和真菌数量较CK样地均有不同程度增加:0～20cm土层微生物数量变化明显,其中N221.0P2O5272.7K2O 303.0和N303.7K2O 180.5两组处理的效果最明显。施肥处理下的土壤磷酸酶、蔗糖酶、脲酶和过氧化氢酶活性均比CK有显著增加(P<0.05),N221.0P2O5272.7K2O 303.0和N303.7K2O 180.5处理的土壤磷酸酶和蔗糖酶活性最高,P2O5272.7处理的土壤脲酶和过氧化氢酶活性最高。土壤纵向分析表明,0～60cm土层土壤细菌、放线菌和真菌数量和土壤脲酶、磷酸酶、蔗糖酶活性均随深度增加而降低。N221.0P2O5272.7K2O303.0配施处理能明显提高枣园土壤微生物数量及磷酸酶和蔗糖酶活性。     

采伐剩余物处理方式对2代杉木林碳储量的影响

在福建南平第1代杉木成熟林中设置固定标准地,采伐前测定每个标准地碳储量,采伐后采用5种方式处理采伐剩余物:全部收获(移走地面上全部有机剩余物,包括树木、林下植被和枯枝落叶)、全树收获(收获树木的全部地上部分)、树干和树皮收获(仅收获树干与树皮)、加倍采伐剩余物(仅收获树干和树皮,将全树收获处理的树枝和树叶移到这个处理中)、炼山(仅收获树干和树皮,然后火烧采伐剩余物),随后采用常规方法营造第2代杉木林。试验后12 a,对不同处理生态系统碳储量进行研究。结果表明:12年生第2代杉木林乔木层碳储量大小顺序为:加倍采伐剩余物(61.03 t·hm-2)>全树收获(57.57 t·hm-2)>全部收获(55.64 t·hm-2)>树干和树皮收获(54.38 t·hm-2)>炼山(49.00 t·hm-2);土壤层(0~40 cm)碳储量大小顺序为:加倍采伐剩余物(99.49 t·hm-2)>全树收获(95.63 t·hm-2)>树干和树皮收获(94.81 t·hm-2)>全部收获(91.55 t·hm-2)>炼山(91.23 t·hm-2,与第1代杉木林采伐前相比,第2代12年生杉木土壤层(0~40 cm)碳储量除了全部收获处理降低0.04 t·hm-2外,其他处理均有少量增加,但差异均不显著。第2代12年生杉木林生态系统总碳储量大小顺序为:加倍采伐剩余物(162.80 t·hm-2)>全树收获(155.56 t·hm-2)>树干和树皮收获(151.24 t·hm-2)>全部收获(149.14 t·hm-2)>炼山(142.29 t·hm-2)。加倍采伐剩余物处理、全树收获处理、树干和树皮收获处理、全部收获处理生态系统碳储量分别比炼山处理高14.41%、9.33%、6.29%、4.81%,但差异均达不到显著水平(P>0.05)。     

Chemical and organic immobilization treatments for reducing phytoavailability of heavy metals in copper‐mine tailings

This study was conducted to evaluate the efficiency of diammonium phosphate (DAP), agricultural limestone (lime), and green‐waste compost mixed with 30% treated sewage sludge (GCS) applied alone or in combination as chemical immobilization treatment using tomato as a test crop. Mine waste was collected from an abandoned copper‐mine tailing site at Mynydd Parys, Anglesey (UK). Lime was applied at the rate of CaCO₃ equivalent (CCE, pH = 7), DAP at the rate of 23 g P per kg substrate, and 10% by weight, GCS as sole application. Half rate of each amendment was also tested as a combined treatment and an untreated substrate (control). Plant‐available metals (Cd, Cu, Fe, Pb, and Zn) were measured in substrate with conventional diethylenetriaminepentaacetic acid (DTPA) and sequential Ca(NO₃)₂ extraction. Plant–dry biomass yield was significantly (p < 0.001) increased by the combined application of all the three amendments while sole application of DAP reduced yield by 4‐fold compared to unamended soil probably due to P toxicity. Addition of lime reduced the DTPA‐extractable Cu, Fe, and Zn by 75%, 81%, and 85%, respectively, while Pb availability was reduced by 88% in combined DAP + lime + GCS treatment compared to control. The extraction capacity of DTPA was higher than that of Ca(NO₃)₂ by 3‐fold for Cu and Fe, 8‐fold for Pb, and 2‐fold for Zn. The leaf‐tissue concentrations of Cu and Fe were reduced by 77% and 83% in the lime + GCS amendment, respectively, while both Pb and Zn were reduced by 89% and 33%, respectively, in substrate treated with the combined application of all three amendments. These results suggest that alkaline amendments (both lime and GCS) were effective in reducing the phytoavailability of Cu, Fe, and Zn while DAP mixed with either GCS or lime was effective in reducing Pb availability.     

PAK-Abnahmen in Bodenproben verschiedener Altlaststandorte bei Aktivierung der autochthonen Mikroflora

PAH decrease in soil samples from different polluted industrial sites by activating the autochthonous microflora In pot experiments under field conditions the PAH decrease in ten different soil samples from former industrial sites with differing PAH load were investigated over a period of 74 and 168 weeks. 15 out of 16 PAH according to US EPA (without acenaphthylene) were determined. Easily degradable organic matter, mineral fertilizers, synthetic surfactants and in some experiments also lime were added to the soil samples in varying amounts. Depending on the nature and quantity of the amendments, the biological activity and (co-)metabolic decomposition of PAH by soil microorganisms could considerably be increased. In the different soil samples a decrease of the initial PAH contents between 12 and 90% was achieved within 74 weeks. Even from 74 up to 168 weeks for some soil samples a remarkable further decrease of the PAH contents could be observed. The decrease of the extractable PAH with time is mainly caused by microbial decomposition and formation of nonextractable residues. This behavior can be fitted by two coupled exponential functions, one for an initial phase of rapid decomposition and the other for a subsequent phase of slow decomposition. Therefore, two different processes (I, II) determine the decrease of PAH. In the first week of the experiment the decomposition rates for process I amount to 4.2–88.3 and for process II to 0.06–5.3 mg PAH ? kg^?1 soil ? week^?1; in the 168th week they are no longer determinable for process I and amount to 0.05–2.3 mg ? kg^?1 ? week' for process II. Higher initial PAH contents often led to higher relative PAH decreases, but also to absolute higher contents of residues. The persistence of PAH is mainly determined by their bioavailability. PAH degradation is increased by the soil treatments. The addition of easily degradable organic matter (C/N ratio < 20) in a quantity of 30g ? kg^?1 (w/w) combined with the addition of nitrate and a surfactant most effectively increased the degradation of PAH. Raising the pH of a very strongly acidic soil sample revealed a maximum PAH decomposition at a pH of 6.     

Cell wall disruption: An effective strategy to improve the nutritive quality of microalgae in African catfish (Clarias gariepinus)

The rigid cell walls of microalgae may hinder their utilization in fish feeds. The current experiment assessed the correlation between the accessibility of microalgae nutrients and their in vivo digestibility in African catfish. Nannochloropsis gaditana biomass was subjected to physical or mechanical treatments to weaken its cell wall; untreated—no disruption treatment (UNT), pasteurization (PAS), freezing (FRO), freeze‐drying (FRD), cold pasteurization (L40) and bead milling (BEM). Six experimental diets formulated from differently treated and untreated microalgae (at 30% diet inclusion level) were tested on growth performance and apparent nutrient digestibility (ADCs) in juvenile African catfish. A basal diet (REF) containing no microalgae was used as reference diet. Results showed that biomass gain and feed conversion ratio of fish fed L40 and BEM diets increased by 13% and 11%, respectively, relative to the UNT diet. Additionally, FRD, FRO, L40 and BEM cell wall disruption treatments improved protein digestibility by 0.5%, 5.9%, 8.4% and 16.3%, respectively, compared to the UNT treatment. There was a positive correlation between accessibility of microalgal nutrients and their digestibility in African catfish. Nutrient digestibility of microalgae was dependent on extent of cell disruption. Also, the impact of cell disruption on nutrient digestibility of microalgae differs between African catfish and Nile tilapia.     

不同药剂处理对猕猴桃根结线虫的防治效果

为了筛选出能够有效防治猕猴桃根结线虫的药剂。采用田间药剂施用筛选的方法,研究了12.5%阿维·噻唑膦EC等7种药剂对猕猴桃根结线虫的防治效果。结果表明供试的不同药剂对猕猴桃根结线虫均有一定的防效,能控制土壤中2龄幼虫的数量和抑制根结的形成,其中12.5%阿维·噻唑膦EC防治效果最好,药后45 d、180 d对根结线虫和二龄若虫的防治效果分别为78.40%、69.90%和83.83%、80.26%;10%噻唑膦GR与5%阿维菌素GR防效较好;2亿/毫升淡紫拟青霉+生物菌培养基B++(微生物肥)防效较差。12.5%阿维·噻唑膦EC、10%噻唑膦GR和5%阿维菌素GR可作为猕猴桃根结线虫防治的首选药剂。     

处理下彩叶草体内元素含量分布及相关性分析

以彩叶草为试材,采用盆栽试验研究了不同浓度Se(0、0.2、0.5、1.0、1.5、2.0、2.5 mg·L^-1)处理下彩叶草各器官中矿质元素(K、Ca、Na、Mg、Fe、Mn、Cu和Zn)和重金属元素(Cr、Cd、As、Pb和Se)含量分布及其相关性。结果表明:Se处理明显改变了根茎叶中矿质元素和重金属的含量及其在植物体内的分布,K和Ca总量在各器官中的顺序是茎>叶>根,Fe和Mn为根>叶>茎,Zn为叶>茎>根;低浓度Se(≤0.5 mg·kg^-1)处理,Na和Mg总量在各器官中的顺序分别是根>茎>叶和叶>根>茎;高浓度Se(≥1.0 mg·kg^-1)处理,Na和Mg元素的顺序则分别为茎>根>叶和叶>茎>根。重金属元素Cr和Cd总量在各器官中的顺序是根>茎>叶;Pb总量在各器官中的顺序是根>叶>茎。相关性分析表明:(1)彩叶草根中Se含量与As、Pb含量呈显著正相关(P <0.05或0.01),与K、Ca、Na、Mg、Fe、Mn、Cu、Zn、Cr、Cd含量的相关性未达到显著水平,13种元素中呈正相关与负相关元素个数相当且基本呈一个复杂的网状结构;(2)茎中Se含量与K、Ca、Na、Mg、Fe、Mn、Cu、Zn、Cr、Cd、As、Pb含量的相关性未达到显著水平,13种元素中正相关元素个数多于负相关元素个数且呈2个简单网状结构;(3)叶中Se含量与Ca含量呈显著负相关(P <0.05),与K、Na、Mg、Fe、Mn、Cu、Zn、Cr、Cd含量的相关性未达显著水平,13种元素中正相关元素个数多于负相关元素个数且呈2个简单直线结构。     

激素处理对杜鹃花自交与杂交种子萌发的影响

杜鹃花种子细小且发芽率低,为探索有效促进种子萌发的方法,选用杜鹃花主栽品种春鹃紫蝴蝶自交种子为材料,通过蒸馏水浸种、GA₃浸种和无菌播种添加NAA、KT、ZT及GA₃的处理方式,比较不同处理对杜鹃花自交种子萌发时间、发芽率等指标的影响。结果表明,蒸馏水浸种处理以24 h浸种的效果最佳,发芽率达43%;无菌播种结合2.0 mg·L^-1 GA₃+0.05 mg·L^-1 NAA处理的效果最佳,发芽率达75%;GA₃浸种以1 600 mg·L^-1 GA₃处理24 h的效果最佳,发芽率可达82%,是对照组的1.82倍。以GA₃浸种法处理杜鹃花2个杂交组合的杂交种子,发现其各项发芽指标均优于对照,其中29号杂交种子的最适GA₃处理为1 200 mg·L^-1浸种24 h,发芽率达96%;59号杂交种子最适GA₃处理为1 600 mg·L^-1浸种24 h,发芽率可达95%,二者发芽率分别比对照提高20%和71%,萌发时间分别提早2和8 d。因此,适宜浓度尤其是高浓度GA₃浸种处理能有效促进杜鹃花自交和杂交种子的萌发。