不同苜蓿种质材料对茎点霉叶斑病的抗性评价

为了明确不同苜蓿材料（Medicago Sativa）对茎点霉叶斑病的抗性,对来自国内外的30份苜蓿材料进行了苗期抗病性评价,采用紫外分光光度计比色法,对不同抗感病材料体内的苯丙氨酸解氨酶（PAL）、过氧化氢酶（CAT）、过氧化物歧化酶（SOD）活性变化进行了研究。结果表明：不同苜蓿材料对茎点霉叶斑病的抗病性存在显著差异,各材料间病情指数（4.28~51.65）变化较大,其中抗病性最强的是来自内蒙的‘敖汉苜蓿’,感病性最强的是来自陕西的‘陕西苜蓿’,中抗材料有10份。接菌前,各材料间CAT,SOD活性差异显著（P<0.05）,而PAL活性差异不显著;接菌后,3种酶活性均比接菌前有所升高,CAT和PAL呈先增后减的趋势,SOD活性呈依次递减趋势;同一材料在接菌后第4,8,12天3种酶活性也表现显著性差异（P<0.05）。     

海洋细菌生物膜用于生物修复陆地生态系统中土壤多环芳烃污染

Polycyclic aromatic hydrocarbons(PAHs) in soil retain for a quite long period due to their hydrophobicity and aggregation properties. Biofilm-forming marine bacterial consortium(named as NCPR), composed of Stenotrophomonas acidaminiphila NCW702,Alcaligenes faecalis NCW402, Pseudomonas mendocina NR802, Pseudomonas aeruginosa N6P6, and Pseudomonas pseudoalcaligenes NP103, was used for the bioremediation of PAHs in a soil microcosm. Phenanthrene and pyrene were used as reference PAHs. Parameters that can affect PAH degradation, such as chemotaxis, solubility of PAHs in extracellular polymeric substances(EPS), and catechol2,3-dioxygenase(C23O) activity, were evaluated. P. aeruginosa N6P6 and P. pseudoalcaligenes NP103 showed chemotactic movement towards both the reference PAHs. The solubility of both the PAHs was increased with an increase in EPS concentration(extracted from all the 5 selected isolates). Significantly(P 0.001) high phenanthrene(70.29%) and pyrene(55.54%) degradation was observed in the bioaugmented soil microcosm. The C23O enzyme activity was significantly(P 0.05) higher in the bioaugmented soil microcosm with phenanthrene added at 173.26 ± 2.06 nmol min~(-1) mg~(-1) protein than with pyrene added at 61.80 ± 2.20 nmol min~(-1) mg~(-1) protein. The C23O activity and gas chromatography-mass spectrometer analyses indicated catechol pathway of phenanthrene metabolism. However, the metabolites obtained from the soil microcosm added with pyrene revealed both the catechol and phthalate pathways for pyrene degradation.     

全球河流输沙量分布格局及其影响因素

研究河流输沙量具有重要的理论和实践意义。近60年在气候变化和人类活动日益增强的背景下,全球众多河流输沙量都发生显著变化。基于全球河流输沙量数据库和区域河流输沙量研究成果,从全球尺度对全球河流输沙量现状、输沙量空间分布格局及其影响因素、输沙量变化及其影响因素3方面进行分析研究。结果表明:(1)全球河流年均总输沙量在2×10~(10) t左右,对全球主要36条河流输沙量数据分析表明大多数河流输沙量显著减少;(2)地质地貌条件是河流输沙量控制性因素,气象水文条件和人类活动对河流间输沙量差异的贡献大致相当;(3)对各气候带的代表性河流研究表明,相比较气候变化,全球河流输沙量变化主要受人类活动的影响。未来全球河流总输沙量会因人类活动尤其是大坝建设的影响而继续减少。     

Effect of nitrogen levels and Rhizobium strains on symbiotic N2 fixation and grain yield of Phaseolus vulgaris L. genotypes in normal and saline-sodic soils

Summary Following screening, selection, characterization, and symbiotic N₂ fixation with 12,5, 25.0, and 40.0 mg N kg^–1 in normal and saline-sodic soils, only two Phaseolus vulgaris genotypes (HUR 137 and VL 63) and two Rhizobium spp. strains (ND 1 and ND 2) produced maximum nodulation, nitrogenase activity, plant N contents, and grain yields in saline-sodic soil, with 12.5 mg N kg^–1, compared with the other strains. However, interactions between strains (USDA 2689, USDA 2674, and ND 5) and genotypes (PDR 14, HUR 15, and HUR 138) were significant and resulted in more nodulation, and greater plant N contents, nitrogenase activity, and grain yields in normal soils with 12.5 mg N kg^–1 compared with salt-tolerant strains. Higher levels of N inhibited nodulation and nitrogenase activity without affecting grain yields. To achieve high crop yields from saline-sodic and normal soils in the plains area, simultaneous selection of favourably interacting symbionts is necessary for N economy, so that bean yields can be increased by the application of an active symbiotic system.     

Human and climatic drivers of land and water use from 1997 to 2019 in Tarim River basin,China

Climate and human activities change spatial and temporal distribution of water and land use. The Tarim River, the largest inland river in China, faced a long-term exploitation of land and water over a rapid economic development. We analyzed land and water use from 1997 to 2019 in Tarim River Basin by Landsat images, and data on hydrology, climate, population, economy and PM_2.5 (air particulate matter ≤2.5 μm). Agricultural land expanded the fastest (4–11%), followed by natural vegetation (15–16%) and water area (4–5%) with population and economic increase. Air quality (PM_2.5 μg m⁻³) improved in upper (62–27) and middle (48–17) reaches. The water area in lower increase 5% because of ecological water delivery since 2000. Land use in the lower reach was dominated by agriculture, where the downstream runoff consumption increased by 6.8 times. The average annual air temperature and precipitation gradually increased by 0.5 °C and 51 mm in source and 0.9 °C and 30 mm in main reaches. The average annual water consumption in upper and middle reaches was 4 × 10⁹ m³, accounting for 87% of input runoff in the main reach. Water consumption in middle reach increased by 33 times in 2009–2017. The industry structure was changing from primary to secondary and tertiary industry. To sum up, implementation of water saving strategies and ecological water delivery restored local ecology. Sustainable strategies should be applied facing industrialization. Furthermore, changing the industry structure and restoring the degraded farmlands to grasslands or forests would keep sustainability of Tarim River Basin.     

镉胁迫下生物炭与锌/钾叶面肥促进烟草生长降低镉富集的协同效应

[目的]生物炭和叶面肥在单独调控重金属胁迫条件下植物生长及重金属离子吸收方面的应用价值已被一些研究证实,然而它们在土壤重金属镉污染修复中的耦合效应及其机制尚不十分清楚。烟草为镉易富集植物,研究生物炭和锌/钾叶面肥单施或联合施用对烟草生长和镉富集特性的影响,为镉污染土壤的修复及烟草安全生产提供理论依据。[方法]采用盆栽模拟轻度土壤镉污染胁迫试验,供试烟草品种为‘中烟100’。设置6个试验处理:对照(CK)、土施生物炭20 g/kg(B)、喷施0.5%ZnSO4叶面肥(Zn)、喷施0.5%KH2PO4叶面肥(K)、生物炭+喷施ZnSO4叶面肥(B+Zn)、生物炭+喷施KH2PO4叶面肥(B+K),每个处理重复8次。将烟草分割为根、茎、下部叶(从下到上1~5片)、中部叶(6~10片)、上部叶(11~15片)5部分。测定株高、生物量、丙二醛含量(MAD)、超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性、烟株各部位的镉含量,计算了镉富集和转运系数,分析了土壤中镉形态的变化。[结果]1)单独施用叶面肥较单独施用生物炭更有利于增强镉胁迫下叶片的抗氧化性能,促进烟株生长。与B处理相比,Zn和K处理的MDA含量分别降低12.8%和15.1%,POD活性分别增加32.2%和29.9%,CAT活性分别增加25.5%和18.2%(P<0.05),Zn和K两处理之间的抗氧化酶活性无显著差异(P>0.05)。单独施用生物炭较单独施用叶面肥更有利于降低土壤中镉的生物有效性。与Zn和K处理相比,B处理的土壤弱酸提取态镉含量分别降低19.0%和19.3%,可还原态镉含量分别降低22.3%和23.9%(P<0.05)。单独喷施叶面肥对土壤镉形态无显著影响(P>0.05)。2)生物炭和叶面肥配施具有叠加效应,且B+Zn处理对促进镉胁迫下烟株生长和减少烟株镉吸收方面效果大于B+K处理。与CK、B、Zn处理相比,B+Zn处理的株高分别增加52.8%、25.9%和11.8%,地上干重分别增加146%、89.1%和45.3%,SOD活性分别增加29.8%、19.7%和11.0%,POD活性分别增加94.0%、64.1%和24.1%,CAT活性分别增加183.8%、90.9%和52.2%,烟株根镉含量分别减少53.9%、25.2%和31.6%,茎镉含量分别减少74.5%、53.9%和63.7%,上部叶镉含量分别减少63.1%、18.8%和40.1%,中部叶镉含量分别减少63.6%、27.7%和35.3%,下部叶镉含量分别减少63.8%、34.1%和46.9%,烟株镉生物富集系数分别降低64.4%、31.0%和48.4%,镉生物转运系数分别降低33.3%、20.2%和28.5%,土壤中弱酸提取态镉含量分别降低19.5%、7.5%和19.0%,土壤中还原态镉含量分别降低22.9%、2.0%和20.8%,土壤中可氧化态镉含量分别增加62.5%、5.6%和54.6%,土壤中残渣态镉含量分别增加206.9%、10.7%和174.7%。与B+K处理相比,B+Zn处理的烟株地上干重增加18.3%,上部叶、中部叶、下部叶镉含量分别减少8.4%、13.9%和16.9%,镉生物富集系数和转运系数分别降低20.8%和8.5%。[结论]在镉污染胁迫下,土施生物炭可以降低土壤中镉的生物有效性,减少烟草的吸收。叶面喷施锌、钾肥可以提高烟草植株的抗氧化性能,促进烟株生长。生物炭配合叶面肥具有明显的协同作用,降低烟草中镉的运转系数和富集系数的效果显著高于锌/钾叶面肥单独施用。在本试验条件下,生物炭配合喷施硫酸锌的效果好于生物炭配合喷施磷酸二氢钾,可作为提高烟草生产安全及土壤镉污染修复的一项有效措施。     

木薯AGPase酶活性及其同工酶位点检测

本文以3个亲缘关系较远的高产木薯品种（SC124,SC8和Arg7）为材料,对块根发育过程中的AGPase活性和淀粉含量进行了测定,并利用AGPase同工酶电泳技术（非变性聚丙烯酰胺凝胶电泳）对AGPase酶活性较高时期同工酶位点进行检测,旨在分析木薯块根AGPase同工酶位点与AGPase酶活性和淀粉积累的关系。结果表明：木薯块根发育过程中AGPase酶活性和淀粉含量呈极显著正相关（R=0．80212）,Arg7的AGPase酶活性和淀粉含量在块根发育都显著高于SC124和SC8。同工酶分析表明,木薯至少有6个同工酶位点（AGPa,AGPb,AGPc,AGPd,AGPe和AGPf）,且品种间具有多态性。其中,3个品种共有的4个同工酶位点分别为AGPa、AGPc、AGPd和AGPf,AGPe位点只在Arg7中出现,初步判断同工酶位点AGPe可能与其较高的酶活性和淀粉含量有关。本研究为系统研究木薯品种间AGPase酶活性与淀粉积累的关系提供了参考。     

乙烯利对甘蔗茎内IAA氧化酶活性动态变化的影响

测定了甘品种桂粮１１号、桂糖１５号和新台糖１６号节间２的ＩＡＡ氧化酶活性的动态变化以及乙烯利处理后的酶活性变化。结果表明：在甘蔗工艺成熟过程中,茎内ＩＡＡ氧化酶酶活性的变化主要表现为先升后降的变化过程,品种间有差异。乙烯利处理对ＩＡＡ氧化酶活性有影响,其影响效应及影响时间因品种而有差异,主要表现为抑制ＩＡＡ氧化酶活性的早期上升过程,同时钝化ＩＡＡ氧化酶对外界环境的反应,酶活性变化对照波动性要小,影     

Phosphate Solubilizing Ability and Phylogenetic Diversity of Bacteria from P-Rich Soils Around Dianchi Lake Drainage Area of China

The phylogenetic diversity of phosphate solubilizing bacteria(PSB)distributed in P-rich soils in the Dianchi Lake drainage area of China was characterized,and the tricalcium phosphate(TCP)solubilizing activities of isolated PSB were determined.Among 1 328 bacteria isolated from 100 P-rich soil samples,377 isolates(28.39%of the total)that exhibited TCP solubilization activity were taken as PSB.These PSB showed different abilities to solubilize TCP,with the concentrations of solubilized P in bacterial cultures varying from 33.48 to 69.63 mg L^-1.A total of 123 PSB isolates,with relatively high TCP solubilization activity(>54.00 mg L^-1),were submitted for restriction fragment length polymorphism(RFLP)analysis,which revealed 32 unique RFLP patterns.Based on these patterns,62 representative isolates,one to three from each RFLP pattern,were seffected for 16S rRNA sequencing.Phylogenetic analysis placed the 123 PSB into three bacterial phyla,namely Proteobacteria,Actinobacteria and Firmicutes.Members of Proteobacteria were the dominant PSB,where 107 isolates represented by 26 RFLP patterns were associated with the genera of Burkholderia,Pseudomonas,Acinetobacter,Enterobacter,Pantoea,Serratia,Klebsiella,Leclercia,Raoultella and Cedecea.Firmicutes were the subdominant group,in which 13 isolates were affiliated with the genera of Bacillus and Brevibacterium.The remaining 3 isolates were identified as three species of the genus Arthrobacter.This research extends the knowledge on PSB in P-rich soils and broadens the spectrum of PSB for the development of environmentally friendly biophosphate fertilizers.     

淹水土壤中镉活性变化及其制约机理

近年来,面对全球土壤Cd污染日益严重的现状,国内外许多专家和学者对土壤中Cd的迁移转化进行了大量的探索和研究。但是,由于土壤自身的复杂性以及影响因素的多样性和不确定性,有关淹水土壤中镉(Cd)活性变化及其制约机理的研究常常出现截然不同甚至相反的报道。铁锰氧化物、碳酸盐、固相有机质、硫化物、DOM、阴离子(主要是Cl-和SO42-)和阳离子(如Al3+、Ca2+、Mg2+、Na+等)等繁多的制约因素及其制约机理使得Cd的土壤化学理论复杂化,也给土壤Cd污染的控制和治理带来困难。本文从Cd在土-水界面发生迁移转化的化学过程(吸附与解吸、沉淀与溶解和配位与螯合)入手,总结并阐述了淹水土壤中Cd活性的变化及其制约机理,同时对该领域的研究进行了展望,试图为淹水土壤中Cd活性的深入研究和Cd污染土壤的修复与治理提供参考。