南充市水稻稻瘟病区划和发生流行规律研究

为提高南充市水稻稻瘟病监测预警和综合防控水平,切实减轻稻瘟病危害,采用GPS和GIS定位、系统监测和普查、品种抗稻瘟性鉴定、稻瘟病菌生理小种监测和气象资料分析等方法,开展了南充市水稻稻瘟病发生流行区划、精准勘界和发生流行规律研究。首次明确了南充市稻瘟病的流行区划和精准勘界,探明了水稻稻瘟病菌越冬后的初始侵染源(即始见期)地点、发生特点、流行趋势和特点,明确了南充市水稻稻瘟病在田间存在4个流行高峰期,其中第1个流行高峰期发生面积对当年病害流行起着决定作用,5月底的累计发生面积与年发生面积成正相关,相关系数为0.8172;建立了孕穗末期病田率和蜡熟期病株率同年发生面积预测数学模型。对其成因探讨发现,导致南充市近年水稻稻瘟病重发及流行的内因是水稻品种抗稻瘟能力的降低或丧失、稻瘟病菌致病力强的生理小种增加与更强致病力的小种出现;温度适宜和阴雨寡照偏多是造成稻瘟病在南充市流行的外因。2001—2015年,全市水稻稻瘟病短期预报准确率达100%,中、长期预报准确率分别达到98%和95%以上,比1997年以前提高5~15个百分点,促进稻瘟病防效提高15%~30%。     

Microbial utilization and mineralization of [14C]glucose added in six orders of concentration to soil

The substrate availability for microbial biomass (MB) in soil is crucial for microbial biomass activity. Due to the fast microbial decomposition and the permanent production of easily available substrates in the rooted top soil mainly by plants during photosynthesis, easily available substrates make a very important contribution to many soil processes including soil organic matter turnover, microbial growth and maintenance, aggregate stabilization, CO₂ efflux, etc. Naturally occurring concentrations of easily available substances are low, ranging from 0.1 μM in soils free of roots and plant residues to 80 mM in root cells. We investigated the effect of adding ¹⁴C-labelled glucose at concentrations spanning the 6 orders of magnitude naturally occurring concentrations on glucose uptake and mineralization by microbial biomass. A positive correlation between the amount of added glucose and its portion mineralized to CO₂ was observed: After 22 days, from 26% to 44% of the added 0.0009 to 257 μg glucose C g^?1 soil was mineralized. The dependence of glucose mineralization on its amount can be described with two functions. Up to 2.6 μg glucose C g^?1 soil (corresponds to 0.78% of initial microbial biomass C), glucose mineralization increased with the slope of 1.8% more mineralized glucose C per 1 μg C added, accompanied by an increasing incorporation of glucose C into MB. An increased spatial contact between micro-organisms and glucose molecules with increasing concentration may be responsible for this fast increase in mineralization rates (at glucose additions <2.6 μg C g^?1). At glucose additions higher than 2.6 μg C g^?1 soil, however, the increase of the glucose mineralization per 1 μg added glucose was much smaller as at additions below 2.6 μg C g^?1 soil and was accompanied by decreasing portions of glucose ¹⁴C incorporated into microbial biomass. This supports the hypothesis of decreasing efficiency of glucose utilization by MB in response to increased substrate availability in the range 2.6–257 μg C g^?1 (=0.78–78% of microbial biomass C). At low glucose amounts, it was mainly stored in a chloroform-labile microbial pool, but not readily mineralized to CO₂. The addition of 257 μg glucose C g^?1 soil (0.78 μg C glucose μg^?1 C micro-organisms) caused a lag phase in mineralization of 19 h, indicating that glucose mineralization was not limited by the substrate availability but by the amount of MB which is typical for 2nd order kinetics.     

Polycyclic aromatic hydrocarbons in atmospheric particulate depositions and urban soils of Moscow,Russia

Purpose

The study was conducted to quantify the polycyclic aromatic hydrocarbons (PAHs) accumulation in urban soils from different functional areas via atmospheric inputs with particulate matter.

Materials and methods

PAH concentration and pattern were measured in the particulate matter of snow depositions, in the upper layers of artificial soils from densely built-up areas and in the undisturbed natural soils (Umbric Retisols) from green park area. Samples were collected in 2011–2013 at 58 sites with different traffic activities located at the territory of the Eastern Administrative Okrug of Moscow. The soil samples and filters with particulate matter were extracted by pressurized liquid extraction using Dionex ASE200. Clean-up analyses were performed on SPE cartridges filled with silica gel. Concentrations of PAHs were determined by high-performance liquid chromatography using an Agilent 1100 System equipped with fluorescent detector.

Results and discussion

Mean values of PAH input with snow particles were 45–57 μg/m² for recreational and residential zones, and 140–264 μg/m² for traffic zones. The samples of depositions from different functional areas showed a similar PAH pattern and consisted primarily of 3–4-ring PAHs. Total PAH concentrations in upper layers of artificial soils showed similar mean values of 1.43–2.21 μg/g for all functional zones. The PAH content in soils from the park area was twofold lower than that from the built-up area (0.34–0.63 μg/g), despite equal levels of atmosphere contamination on these territories. The upper layers of natural soils from recreational and traffic zones showed slight differences in PAH content, though PAH input with snow was fivefold higher in the traffic zone. Compared with airborne depositions, soils contained significant amounts of 5–6-ring PAHs.

Conclusions

A high level of soil PAH contamination in urban areas of Moscow, several orders of magnitude higher than the current PAH input to them from the atmosphere, indicates a lack of direct connection of the PAH pool in soils with this source. The high PAH content in the upper layer of constructed soils can be the result of repeated use of materials subjected to a constant technogenic impact for the production of artificial soils.

     

施肥投入对招远农田土壤酸化及养分变化的影响

【研究目的】分析当前招远市不同栽培体系下农田施肥对土壤酸化和土壤养分变化的影响;【方法】通过对农田养分投入的调查,结合大量田间采样和1981年土壤普查资料,分析目前土壤pH、养分的变化特点以及这种变化特点所可能导致的一些问题和原因;【结果】农田出现土壤有机质含量偏低、土壤有效磷出现积累与土壤钾含量低的失衡状况;土壤酸化比较严重,60％以上的农田土壤pH值低于5．5;土壤酸化造成土壤微量元素铁、锰、铜等超标。过量的氮素供应,在投肥品种上没有考虑碱性肥料等因素造成土壤酸化。而土壤微量元素的过量积累与土壤酸化关系十分密切;【结论】招远市农田投入养分失衡等施肥措施是造成土壤酸化的主要原因。土壤酸化造成土壤中量元素的缺乏和某些重金属超标,成为生产上的障碍因子。有机肥施用偏低是土壤有机质含量偏低的主要原因。今后应该根据土壤养分状况、酸化状况。有针对性开展测土配方施肥研究,以推进本市农业向高产、优质、高效发展。     

Development of a prototype 16S rRNA gene-based microarray for monitoring planktonic actinobacteria in shrimp ponds

Many reports have shown that the composition of the bacterioplankton community can serve as a biological indicator to evaluate the occurrence of shrimp diseases. However, the distribution, diversity, and function of planktonic actinobacteria in shrimp ponds are still poorly understood. In this study, a prototype of a 16S rRNA gene-based taxonomic microarray was developed and evaluated for monitoring of planktonic actinobacteria in shrimp ponds. The prototype microarray is composed of 30 probes that target ten dominant families of planktonic actinobacteria found in shrimp ponds. The specificity of the actinobacterial microarray was validated by a set of control hybridizations with 16S rRNA genes clones. The prototype microarray was subsequently tested with two seawater samples from ponds with diseased shrimp populations (PDS) and ponds with healthy shrimp populations (PHS). The actinobacteria hybridization profiles revealed a lower abundance of Microbacteriaceae and a higher abundance of Mycobacteriaceae in PDS than in PHS. The changes in planktonic actinobacterial communities were validated by pyrosequencing data. These results support the utility of the microarray for monitoring planktonic actinobacteria in shrimp ponds and aquaculture environments.

     

施肥投入对招远农田土壤酸化及养分变化的影响

【研究目的】分析当前招远市不同栽培体系下农田施肥对土壤酸化和土壤养分变化的影响;【方法】通过对农田养分投入的调查,结合大量田间采样和1981年土壤普查资料,分析目前土壤pH、养分的变化特点以及这种变化特点所可能导致的一些问题和原因;【结果】农田出现土壤有机质含量偏低、土壤有效磷出现积累与土壤钾含量低的失衡状况;土壤酸化比较严重,60％以上的农田土壤pH值低于5．5;土壤酸化造成土壤微量元素铁、锰、铜等超标。过量的氮素供应,在投肥品种上没有考虑碱性肥料等因素造成土壤酸化。而土壤微量元素的过量积累与土壤酸化关系十分密切;【结论】招远市农田投入养分失衡等施肥措施是造成土壤酸化的主要原因。土壤酸化造成土壤中量元素的缺乏和某些重金属超标,成为生产上的障碍因子。有机肥施用偏低是土壤有机质含量偏低的主要原因。今后应该根据土壤养分状况、酸化状况。有针对性开展测土配方施肥研究,以推进本市农业向高产、优质、高效发展。     

不同养殖模式对凡纳滨对虾肠道微生物群落的影响

为了探究不同养殖模式下凡纳滨对虾肠道微生物群落组成的差异,本研究采用16S rRNA扩增子测序技术对4种不同养殖模式[淡水池塘养殖模式(FWP)、海水池塘养殖模式(SP)、高位池养殖模式(HP)和生物絮团养殖模式(BFP)]下凡纳滨对虾的肠道微生物多样性和群落结构进行了研究.结果 显示,FWP和HP下凡纳滨对虾肠道菌群...     

食用真菌空间诱变育种研究

本研究将香菇、平菇、黑木耳、金针菇、灵芝等食用菌材料进行了卫星或高空气球搭载,随之进行地面实验。结果表明,搭载材料在拮抗反应、菌丝生长速度、出菇形态等方面出现明显变异。RAPD分析的结果也证实一些搭载菌株在DNA水平上发生了变异。以上结果表明,空间诱变可能为食用菌的遗传育种提供新途径。     

铁矿采矿迹地不同恢复年限植被生态系统碳密度空间格局

以北京首云铁矿尾矿库采矿迹地利用覆盖客土加生态植被毯措施9年来恢复植被为研究对象,采用空间替代时间的方法,对不同恢复年限的植被生态系统碳密度空间格局进行研究,结果表明:随着恢复年限的增加,恢复植被地上部分碳密度呈现先降低再增加的趋势,恢复5年后植被地上部分碳密度趋于稳定;根系碳密度随着恢复年限与地上部分碳密度呈相同的趋势;枯落物碳密度随恢复年限呈增加趋势,恢复6年后碳密度变化趋于稳定;土壤有机碳密度随恢复年限呈现增加趋势,各层有机碳密度均显著低于周边自然植被土壤有机碳密度,周边植被土壤有机碳密度为恢复植被土壤碳密度的2.07~2.87倍,铁矿采矿迹地恢复过程中土壤碳库具有较大的碳汇潜能。