Optimizing the initial moisture content during composting is an important phenomenon for promoting microbial processes and nutrient dynamics in compost. Therefore, a study was carried out at Gansu Agricultural University, China (36°02′N, 104°25′E; 2400 m a.s.l.) to assess how an initially optimized moisture content (45% MC = MC1, 55% MC = MC2 and 65% MC = MC3) affects the decomposition of corn straw and cow manure mixture in a bioreactor system during winter. The results obtained show that all treatments, except MC1, entered the thermophilic phase (>50 °C) on day 3, with peak temperatures observed on day 7 for 55% MC (57.8 °C), day 9 for 45% MC (51.5 °C), and day 11 for 65% MC (56.7 °C). Despite the initial differences in moisture, the electrical conductivity (EC) values stabilized in the final phase of composting and were between 2.96 and 3.01 mS/cm for all treatments. The 65% MC outperformed the other treatments in microbial metrics. It had the highest microbial biomass carbon (MBC =254.81 mg/kg) and nitrogen (MBN = 26.38 mg/kg), corresponding to 6.7% and 6.9% increases over the 55% MC, and 14.8% and 26.4% over the 45% MC, respectively. The dissolved organic nitrogen (DON) content followed the trend 21.2 mg/g (MC3) > 19.6 mg/g (MC2) > 14.4 mg/g (MC1), with MC3 showing an increase of 47.2% and 8.2% over the MC1 and MC2, respectively. The total phosphorus (TP) content increased by 14.9%, 27.4%, and 35.2% for 45% MC, 55% MC, and 65% MC, respectively, compared to the baseline values. The extent of moisture loss was inversely proportional to the initial moisture content, with MC1 (44%) showing the highest losses, while MC3 showed the lowest (23.4%). These results suggest that optimizing the initial moisture content of corn straw and cow manure mixture to 65% significantly improved the stimulation of microbial biomass, nutrient retention and overall quality of the compost.

为揭示不同pH值对好氧堆肥中NH3挥发和氮素化合物转化的影响,设置5个处理(T1:对照;T2～T4:pH值分别为8.5、7.5和6.5;T5:酸性添加剂,10％过磷酸钙),研究不同pH值和酸性添加剂对好氧堆肥中NH3挥发和氮素化合物转化的影响.试验结果表明,堆肥的高温期氨挥发量占总挥发量的95％以上.降低堆体pH值可以有效降低氨挥发,且初始pH值越低,氨挥发量越少.至堆肥结束,与T1处理相比,T2～T4处理的NH3累计排放量分别减少了35.8％、66.93％和84.48％.添加过磷酸钙能使堆体pH值降低0.03～0.09个单位,使氨挥发减少62.42％.至堆肥结束,T1、T2、T3和T5处理NH4+-N含量均下降到0.04 g·kg-1以下的水平,而T4处理NH4+-N含量最大为0.17 g·kg-1.说明T4处理有利于促进反硝化作用的进行.T3处理的NO3--N和酸解有机氮含量均高于T1、T2和T4处理.说明T3处理有利于促进硝化作用和氨同化作用的进行.与T1处理相比,T5处理NH4-N含量增加了8.56％,NO3--N含量减少了30％,酸解有机氮含量增加了2.52％,这说明,过磷酸钙的添加有利于促进氨同化作用的进行,但是抑制了反硝化作用的进行.

Objectives: Anaerobic fungi are critical for nutrient digestion in the yak rumen. Although studies have reported the effects of passage at different time intervals on the community structure of yak rumen anaerobic fungi, it is unknown whether passage culture at different time intervals affects the microbial proteins of rumen anaerobic fungi and their functions.Methods: Mycelium was obtained using the anaerobic continuous batch culture (CBC) of yak rumen fluid at intervals of 3 d, 5 d and 7 d. Quantitative analysis of fungal proteins and functional analysis was performed using tandem mass tagging (TMT) and bioinformatics. Results: A total of 56 differential proteins (DPs) were found in 5 d vs. 3 d and 7 d vs. 3 d. Gene ontology (GO) enrichment indicated that the up-regulated proteins were mainly involved in biological regulation, cellular process, metabolic process, macromolecular complex, membrane, cell part, organelle, binding, catalytic activity and transporter activity. The downregulated proteins were mainly enriched in metabolic process, cell part, binding and catalytic activity. Furthermore, the downregulated proteins in 7 d vs. 3 d were related to membrane and organelle. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment results indicated that DPs were enriched in 14 pathways in 5 d vs. 3 d and 7 d vs. 3 d, mainly including terpenoid backbone biosynthesis, alaine, aspartate and glutamate metabolism, arginine biosynthesis, hypotaurine, cyanoamino acid, glutathione, beta-alanine, pyrimidine, purine, galactose and propanate metabolism, steroid biosynthesis, ribosome biogenesis in eukaryotes and aminoacyl tRNA biosynthesis. The DPs were enriched in only 2 pathways in 5 d vs 3 d, lysine biosynthesis and cysteine and methionine metabolism. N-glycan biosynthesis and retinol metabolism are only found in the metabolism of DPs in 7 d vs 3 d.Conclusions: Yak rumen anaerobic fungal proteins are involved in nutrition and stress tolerance during passage at different time intervals.

Humic substances affect compost stability and maturation. However, the intricate structure of lignocellulosic materials hinders the biodegradation of cellulose, hemicellulose, and lignin, often promoting the use of synthetic additives which results in microbial inactivation and death. Therefore, this study examined the effects of optimal moisture levels (MC1 = 45%, MC2 = 55%, and MC3 = 65%) on lignocellulosic and humification fractions in aerobically composted straw and manure. The study showed that 65% moisture content was more efficient in decomposing cellulose, hemicellulose, and lignin, with hemicellulose (115.3% w/w ≈ 47.1%) degrading more than cellulose (76.0% w/w ≈ 39.5%) and lignin (39.9% w/w ≈ 25.9%). However, in compost heaps with 45% moisture, the humic acid concentration increased significantly by 12.4% (3.1% w/w) and 17.3% (4.3% w/w) compared with 55% and 65% moisture, respectively. All moisture levels increased the mineralization of humic substances, but the index measured was highest at 65% MC (23.8% w/w) and lowest at 45% MC (18% w/w). In addition, the humification rate showed the trend: 0.083% w/w > 0.087% w/w > 0.100% w/w for MC1, MC2, and MC3, respectively. Overall, the results indicate that an initial moisture content of 65% is aerobically efficient for the conversion of corn straw and cow manure into stable and mature compost.

To study the microbial community succession during cow manure composting under different ventilation conditions,using cow manure and straw as raw materials,two treatments of continuous ventilation (K1,aeration rates 0.2 L·kg -1 ·min -1 ) and intermittent ventilation (K2,average aeration rates 0.2 L·kg -1 ·min -1 ;aerate 10 min,stop 10 min) were set up to carry out aerobic composting experiment in the reactor.The microbial community succession and response to environmental factors were analyzed by high-throughput sequencing technology.The results showed that the bacterial and fungal community structure changed greatly in the entire composting.In the initial stage of composting,Proteobacteria （62.07%） in mixed raw materials of cow manure and corn straw was the dominant phylum of bacteria.Firmicutes was the dominant phyla in the thermophilic period,the relative abundance of Firmicutes in K2 treatment （83.09%） was significantly higher than K1 treatment （57.79%）.Bacillus and Solibacillus were the predominant groups in the thermophilic period of composting.The relative abundance of Bacillus in K1 and K2 treatments were 13.67%and 32.61%,respectively,and the relative abundance of Solibacillus were 7.2%and 23.05%,respectively.Ascomycota and Basidiomycota were the dominant phylum of fungi in the whole composting process.In the thermophilic period of composting,the proportion of Ascomycota in K1 and K2 treatments were58.11%and 78.11%,respectively.The relative abundance of Kurtzmaniella-Candida clade in K2 treatment （25.67%） was significantly higher than that in K1 treatment （7.85%）,which was the dominant genus in the thermophilic period of composting.The redundancy analysis （RDA） results showed that temperature,NH 4 + -N and C/N ratio were the main environmental factors affecting the bacterial and fungal community structure during the thermophilic period.The pH value,NO 3 - -N and TN had great influence on the bacterial and fungal community structure in cooling and maturity stage.Intermittent ventilation was beneficial to the increase of the relative abundance of Firmicutes in the thermophilic period of composting,and significantly increased the relative abundance of Bacillus and Solibacillus.Intermittent ventilation was beneficial to the increase of relative abundance of Ascomycota and Kurtzmaniella-Candida clade in the thermophilic period.

Soil organic matter (SOM) fractions play a key role in sustaining soil productivity; however, these fractions are relatively low in agricultural soils due to crop residue removal and tillage practices. Straw return has been reported to improve SOM fractions; however, its effects on soils with different nitrogen status is lacking. Therefore, a two-year experiment was conducted on an existing five-year different nitrogen rates (0, 75, 150 and 375 kg Nha- 1 yr-1) trial field to assess the effects of nitrogen fertilizer rate and straw return on SOM fractions at different soil depths. The experiment had four nitrogen rates: 0 (CK, control), 75 (low N, LN), 150 (medium N, MN), and 375 (high N, HN) kg Nha- 1 yr-1 with and without straw return (S, 9 t ha-1). The results showed that straw return significantly stimulated the SOM fractions at both 0-20 and 20-40 cm soil depths. Compared with the control, treatment MN with straw increased carbon pool management index (28.52 %), dissolved organic carbon (45.89 %), microbial biomass carbon (66.11 %), readily organic carbon (27.07 %), humic acid carbon (21.69 %), and humin carbon (10.34 %) at 0-20 cm soil depth; however, these fractions were comparable to those of HN with straw. Total organic carbon and carbon pool management index showed a positive and significant correlation with labile SOM fractions in the soil. The application of 150 kg N ha-1 after straw return stimulates SOM fractions, which in turn maintains the fertility and productivity of loess soil.

通过土培收集、硅烷衍生化分离、气质联用鉴定马铃薯苗期、现蕾期及盛花期根系分泌物的主要成分,并采用半固体平板法、类毛细管法和结晶紫染色法比较观察马铃薯不同生育时期根系分泌物及氨基酸对萎缩芽孢杆菌QHZ3 趋化成膜的影响,以揭示菌株QHZ3 在马铃薯根际的定殖机制.马铃薯根系分泌物鉴定中发现了 5 种氨基酸:脯氨酸、甘氨酸、天冬氨酸、苯丙氨酸和酪氨酸.定性试验显示,马铃薯不同生育时期的根系分泌物和除脯氨酸之外的其他 4 种氨基酸均对菌株QHZ3 具有显著的正趋化作用,并以甘氨酸的作用最强,其趋化圈直径(6.40 cm)是对照(3.48 cm)的1.84 倍;定量试验结果表明,根系分泌物(120 μg?mL-1和240 μg?mL-1)、甘氨酸(10～50 μmol?L-1)、天冬氨酸(50～75 μmol?L-1)和苯丙氨酸(25～50 μmol?L-1)均对菌株QHZ3 有显著正趋化作用,尤其以 25 μmol?L-1的甘氨酸趋化性指数最大,其毛细管中细菌数量(5.13×105 CFU?mL-1)达到对照组(1.53×105 CFU?mL-1)的 3.3 倍;结晶紫染色法显示,现蕾期和盛花期根系分泌物以及甘氨酸(25～100 μmol?L-1)、脯氨酸(75～100 μmol?L-1)和苯丙氨酸(25～100 μmol?L-1)均对菌株QHZ3 生物膜的形成有显著促进作用.根系分泌物和氨基酸均对菌株QHZ3 在马铃薯根际趋化成膜具有促进作用,但 5 种氨基酸的作用各不相同,其中天冬氨酸和酪氨酸显著影响菌株的趋化作用,脯氨酸显著影响了菌株生物膜的形成,而甘氨酸和苯丙氨酸则对菌株的趋化和成膜兼具显著效果.

The morphology and infraciliature of two soil hypotrichous ciliates, Heterourosomoida lanceolata (Shibuya, 1930) Singh and Kamra, 2015 and Gastrostylides dorsicirratus (Foissner, 1982) Foissner, 2016, were investigated using live observation and protargol staining. The Chinese population of H. lanceolata differs slightly from other populations in the body size in vivo, the relative length of the adoral zone, the number of right and left marginal cirri, the total number of dorsal bristles, and the number of micronuclei. The Chinese population of G. dorsicirratus corresponds well with Austrian and Indian populations. We also document the morphogenetic processes during binary fission of G. dorsicirratus, including the formation of the frontoventral-transverse cirral anlagen in a primary pattern. In addition, phylogenetic analyses based on SSU rDNA sequence data reveal that the two populations of G. dorsicirratus for which data are available cluster together with full support and form a clade with Heterourosomoida sinica and two populations of H. lanceolata.

为研究枯萎病对马铃薯光合特性的影响,在幼苗期接种尖孢镰刀菌Fusarium oxysporum后,统计抗病品种陇薯10号和感病品种新大坪的病情指数,并测定叶绿素含量、光合及荧光参数.结果表明,尖孢镰刀菌侵染30 d后马铃薯表现出枯萎病症状,叶绿素含量显著降低,其中叶绿素a含量降幅最大,抗病品种陇薯10号比对照降低9.64％,感病品种新大坪比对照降低14.24％.尖孢镰刀菌侵染后马铃薯光合效率显著降低,侵染30 d后,抗病品种陇薯10号净光合速率比对照降低39.56％,感病品种新大坪比对照降低47.13％.病株的光响应曲线参数光补偿点、暗呼吸速率和表观量子效率都显著提高;而光饱和点和最大净光合速率都显著低于对照,表明尖孢镰刀菌侵染缩小了马铃薯对光能的利用有效范围.病株CO2响应曲线参数CO2饱和点、最大净光合速率和羧化效率分别显著低于对照;病株CO2补偿点和光呼吸速率反而升高,说明碳同化过程受到尖孢镰刀菌的限制.暗适应下的初始荧光、最小荧光、最大荧光、PSII最大光化学效率、光适应下PSII最大光化学效率及实际光化学效率、光化学猝灭系数、非光化学猝灭系数和光合电子传递速率均显著低于对照,说明光合色素含量的降低导致PSII反应中心捕光能力减弱,尤其是叶绿素a含量的降低导致了光化学转化效率降低,从而使马铃薯净光合速率降低.尖孢镰刀菌侵染对马铃薯的生长发育产生了较大影响,株高、主茎数、结薯数量、经济产量和生物产量显著降低,且抗病品种陇薯10号的这些指标降低幅度小于感病品种新大坪.陇薯10号发病株光合色素含量、光合特性和农艺性状等参数降低幅度都小于新大坪.

The tuber yield of potato in China is relatively low compared to the average global yield, partly due to poor nitrogen (N) management. Moreover, excessive N fertilization reduces the nitrogen use efficiency (NUE) of potato and increases production costs, which reduces profit margins. Therefore, a 2-year field trial was conducted on an existing field with 5 years of different inorganic N fertilization rates in Dingxi to determine the effects of N fertilization rate on growth, tuber yield, net income and NUE of potato on a loess soil. The experiment included six N fertilization rates, namely 0 kg N ha−1 (N0), 75 kg N ha−1 (N1), 150 kg N ha−1 (N2), 225 kg N ha−1 (N3), 300 kg N ha−1 (N4) and 375 kg N ha−1 (N5). The treatments were laid out in a randomized complete block design and replicated four times. The results from the principal component analysis revealed that N fertilization has a strong effect on potato growth, tuber yield and NUE. Treatment N2 increased total tuber yield (29.0% and 33.1%) and net income (54.8% and 61.4%) of potato in 2018 and 2019 seasons, respectively, compared to the control. Excessive N fertilization (N5) reduced tuber yield, net income and NUE of potato in both seasons. To increase tuber yield, net income and NUE of potato (cultivar Qingshu 9) on a loess soil of Northwest China, N fertilization rate should not exceed 150 kg ha−1.

Isatis indigotica planting is the backbone of the medicinal industry in Hexi Oasis, Gansu. In order to solve the problems insufficient water resources and excessive application of nitrogen fertilizer in this area, this paper explored the irrigation and nitrogen levels that can meet the multiple goals of Isatis indigotica . The two-factor split-plot field experiment (2018‒2019) was conducted in Minle County, Gansu Province, China, which contains 9 treatments. There were three levels of irrigation water: W1(low), W2(medium), and W3(high). The soil moisture contents were 60–70%, 70–80%, and 80–90% of the field water-holding capacity, respectively. The nitrogen application rate was classified into three levels, N1(low), N2(medium) and N3(high), which were 150, 200 and 250 kg N/ha, respectively. The standard local irrigation water amount and nitrogen application rate corresponded to W3N3. The results showed that the yield of Isatis indigotica increased first and then decreased with the increase of irrigation amount and nitrogen application rate, the yield of W2N2 is 12.2–17.1% higher than that of W1N1, the yield of W3N3 was 12.1–17.5% lower than that of W2N2. Saving water and reducing nitrogen can improve the quality of Isatis indigotica , compared with W3N3, the indigo, indirubin, (R,S)-epigoitrin and polysaccharides of W2N2 increased by 4.5–5.9%, 2.7–3.1%, 5.2–6.0%, and 1.8–2.1%, respectively. With the increase of nitrogen application rate, the water use efficiency (WUE) first increased and then decreased, as the irrigation volume increases, WUE decreases. Compared with W3N3, the WUE of W2N2 increased by 24.3–27.2%. With the increase of water input, the nitrogen fertilizer use efficiency (NUE) first increased and then decreased, as the nitrogen application rate increases, NUE decreases. Compared with W3N3, the NUE of W2W2 increased by 31.8–34.5%. Therefore, W2N2 can improve quality and increase water and nitrogen utilization efficiency on the basis of ensuring yield.

为揭示基于不同施氮量的玉米秸秆还田对土壤有机碳组分的影响,通过田间定位试验,设置N0、S+N0、S+N75、S+N225、S+N375五个处理,以秸秆不还田不配施氮肥(N0)为对照,研究不同施氮量的玉米秸秆还田对土壤有机碳及其活性碳组分的影响.试验结果表明,不同施氮量的玉米秸秆还田处理土壤总有机碳(TOC)、土壤溶解性有机碳(DOC)和土壤微生物生物量碳(MBC)的含量均高于秸秆不还田处理,同时,施氮量过多时,土壤微生物生物量碳含量降低.因此,秸秆还田配施适量氮肥可以提高土壤有机碳的含量.

[背景]马铃薯黑痣病是由立枯丝核菌(Rhizoctonia solani)引起的一种典型土传病害,目前该病害生物防治的菌种资源比较有限,相应菌株生防机制的研究更是缺乏.[目的]明确马铃薯黑痣病病原菌立枯丝核菌(R.solani) JT18的拮抗菌QHZ11对马铃薯黑痣病的生防效果,揭示QHZ11对黑痣病的部分防治机理.[方法]在灭菌土壤中分别接种R.solani JT18 (CK),R.solani JT18和普通有机肥(Organic Fertilized,OF),R.solani JT18和氨基酸有机肥(AA+OF)及R.solani JT18和QHZ11生物有机肥(BOF11),结合实时荧光定量PCR (Real-Time Fluorescence Quantitative PCR,RT-qPCR)等方法,研究马铃薯全生育期不同处理R.solani JT18在马铃薯根际和植株不同部位的数量变化及拮抗菌QHZ11与R.solani JT18的数量消长规律,同时比较不同处理黑痣病的病情指数及相应的防效.[结果]RT-qPCR结果表明,随马铃薯生育进程的推进,马铃薯根际、根系和匍匐茎R.solani JT18的数量在各处理中均呈现先升高至块茎膨大期到达峰值后下降的趋势,而且各部位R.solani JT18的数量为CK＞OF＞AA+OF＞BOF11且根际＞根系＞匍匐茎;拮抗菌QHZ11的数量变化趋势与R.solani JT18相同,但峰值在块茎形成期,并且同时期同一部位QHZ11的定殖数量均显著高于R.solani JT18,甚至高出2个数量级,说明QHZ11占用了一定的营养资源和生态位点,严重抑制了R.solani JT18的生长和繁殖.病情结果表明:CK病情指数最高,OF、AA+OF和BOF11处理均显著低于CK,其中BOF11处理发病最轻;生防结果则相反,为BOF11 ＞AA+OF＞OF处理,说明普通有机肥、氨基酸有机肥及生物有机肥均可不同程度地防治马铃薯黑痣病,其中以生物有机肥效果最显著.[结论]QHZ11以有机肥为载体施入土壤后,可以通过在马铃薯根际及植株不同部位竞争营养和生态位点,从而有效抑制黑痣病病原菌R.solani JT18的生存和繁殖,起到显著的生防效果,这对QHZ11生物有机肥的应用和推广具有重要意义,并为进一步研究QHZ11的生防机制奠定了基础.

This study aimed to investigate the effect of swine manure composting with microbial inoculation (MI) and without MI (CK) on heavy metal (Cr, Cd, and Pb) fractions, humic substance (HS), and metabolism pathway. The results showed that MI could passivate the heavy metal Cr and reduce the proportion of exchangeable (EXC) fraction of Cd, but it does not affect the EXC fraction of Pb. Compared to CK, HS, humic acid (HA), and fulvic acid (FA) were significantly increased with MI at the maturity stage. The propagation of Proteobacteria (day 4) and Firmicutes (days 12 and 24) was strengthened with MI. Canonical correlation analysis found that HA and Firmicutes were positively correlated with heavy metal (Cr, Cd, and Pb) residual (RES) fraction, and FA was positively correlated with Proteobacteria. Moreover, MI can significantly increase amino acid metabolism and carbohydrate metabolism by day 4, enhance the metabolism of enzyme families and glycan biosynthesis by day 12, and improve membrane transport. Overall, MI could facilitates the increase in HA and FA content and transfer of heavy metal (Cr, Cd, and Pb) fractions, it particularly helps increase the RES fraction.

为了揭示马铃薯连作化感物质与枯萎病之间的关系,通过水培和田间长期定位试验相结合方法,收集不同连作年限马铃薯根系分泌物,采用GC-TOF-MS进行分离鉴定.结果表明:在检测到的马铃薯根系分泌的48种物质中有机酸占30种.比较轮作、连作5年和连作10年马铃薯根系分泌物中有机酸的相对含量,发现苹果酸和棕榈酸的差异比较大.马铃薯连作条件下根系分泌物能显著增强尖孢镰孢菌(Fusarium oxysporum)的发育并加重枯萎病发生.通过外源添加法研究苹果酸和棕榈酸对尖孢镰孢菌的化感作用,苹果酸和棕榈酸浓度分别在0.10-0.50 mmol·L-1和0.05-0.10 mmol·L-1对尖孢镰孢菌生长起到显著的促进作用.盆栽试验表明,浓度0.05-0.50 mmol·L-1苹果酸和棕榈酸对马铃薯枯萎病有显著的促进作用.这说明苹果酸和棕榈酸是马铃薯根系分泌的化感自毒物质,对尖孢镰孢菌生长起促进作用是连作马铃薯枯萎病发病主要原因.

The objective of this research was to explore the effects of different aeration methods on NH3 and greenhouse gas (GHG) emissions and the losses of carbon and nitrogen from composting of cow manure and corn stalks in the laboratory-scale reactors. Here, we designed three treatments, including continuous aerated treatment C1 (aeration rates 0.21 L·kg−1 dry matter (DM)·min−1) and intermittent aerated treatments I1 (aeration rates 0.42 L·kg−1 DM·min−1; aerate 10 min, stop 10 min) and I2 (aeration rates 0.84 L·kg−1 DM·min−1; aerate 5 min, stop 15 min). The results showed that the physicochemical parameters (temperature, pH values, and germination index) of composting products met the requirements of maturity and sanitation. Compared with continuous aerated treatment C1, the cumulative NH3 emissions of I1 and I2 treatments decreased by 24.37% and 19.27%, while the cumulative CO2 emissions decreased by 13.01% and 20.72%. On the contrary, the cumulative N2O emissions of I1 and I2 treatments increased by 22.22% and 43.14%. CO2 emission was the principal pathway for the TOC losses, which comprised over 65% of TOC losses. C1 treatment had the highest TOC losses due to its highest cumulative CO2 emissions. The TN losses of I1 and I2 treatments reduced 9.07% and 6.1% compared to C1 treatment, so the intermittent aerated modes could reduce the TN loss. Due to the potential for mitigation of gaseous emissions, I1 treatment was recommended to be used in aerobic composting of cow manure.

Amino sugars are key microbial biomarkers for determining the contribution of microbial residues in soil organic matter (SOM). However, it remains largely unclear as to what extent inorganic nitrogen (N) fertilization can lead to the significant degradation of SOM in alkaline agricultural soils. A six-year field experiment was conducted from 2013 to 2018 to evaluate the effects of chronic N enrichment on microbial residues, amino sugars, and soil biochemical properties under four nitrogen (urea, 46% N) fertilization scenarios: 0 (no-N, control), 75 (low-N), 225 (medium-N), and 375 (high-N) kg N ha−1. The results showed that chronic N enrichment stimulated microbial residues and amino sugar accumulation over time. The medium-N treatment increased the concentration of muramic acid (15.77%), glucosamine (13.55%), galactosamine (18.84%), bacterial residues (16.88%), fungal residues (11.31%), and total microbial residues (12.57%) compared to the control in 2018; however, these concentrations were comparable to the high-N treatment concentrations. The ratio of glucosamine to galactosamine and of glucosamine to muramic acid decreased over time due to a larger increase in bacterial residues as compared to fungal residues. Microbial biomass, soil organic carbon, and aboveground plant biomass positively correlated with microbial residues and amino sugar components. Chronic N enrichment improved the soil biochemical properties and aboveground plant biomass, which stimulated microbial residues and amino sugar accumulation over time.

[背景]根系分泌物介导的微生物趋化成膜是根际促生菌在根际定殖及功能发挥的重要前提,深入了解该过程对理解菌株定殖机制具有重要意义.[目的]探明马铃薯根系分泌物中使萎缩芽孢杆菌促生菌株QHZ3在根际趋化成膜的信号物质.[方法]通过高效液相色谱鉴定马铃薯根系分泌物中的主要酚酸类物质,采用半固体平板法与类毛细管法比较马铃薯根系分泌物和不同酚酸类物质对促生菌株QHZ3趋化作用,并通过结晶紫染色法观察马铃薯根系分泌物和不同酚酸类物质对菌株QHZ3生物膜形成的影响.[结果]马铃薯根系分泌物中的酚酸类物质主要包括富马酸、对羟基苯甲酸、阿魏酸和肉桂酸.半固体平板法结果显示,马铃薯根系分泌物和4种酚酸对菌株QHZ3均具有趋化作用,富马酸的趋化作用最强;类毛细管定量试验结果表明,不同浓度酚酸对菌株QHZ3的趋化作用不同,中高等浓度的富马酸(25-100 μmol/L)和低浓度的阿魏酸(10 μmol/L)对菌株QHZ3的趋化作用最强;结晶紫染色法结果表明,120-240 μg/mL马铃薯根系分泌物和50-75 μmol/L富马酸及100 μmol/L对羟基苯甲酸可显著促进菌株QHZ3生物膜的形成,而阿魏酸和肉桂酸对菌株的生物膜形成没有显著影响.[结论]根系分泌物和酚酸均可介导菌株QHZ3在马铃薯根际趋化成膜,但4种酚酸的作用不同,富马酸和阿魏酸对菌株的趋化作用显著,富马酸和对羟基苯甲酸则是对菌株生物膜的形成具有显著影响.

[背景]生防菌在作物根系的有效定殖是其功能发挥的前提,而直观的跟踪技术和有效的定量方法是研究生防菌根系分布规律的重要工具.[目的]研究马铃薯黑痣病病原菌立枯丝核菌(Rhizo ctonia solani) JT18的拮抗菌QHZ11在马铃薯植株上的定殖特征及对马铃薯的促生效果.[方法]采用绿色荧光蛋白(Green Fluorescent Protein,GFP)对QHZ11进行标记,将标记菌株菌悬液、生物有机肥和无菌水分别接种至灭菌土壤,通过激光共聚焦显微技术和实时荧光定量PCR等方法观察和测定标记菌株在马铃薯植株不同部位的定殖特征、数量变化及对马铃薯的促生效果.[结果]pHAPII质粒成功导入QHZ11并可稳定遗传40代,记为QHZ11-gfp;菌株标记前后的菌落形态、生长曲线和对R.solani JT18的拮抗能力等基本一致.从第7天开始,相继在马铃薯芽上和根上发现了绿色荧光,说明QHZ11-gfp成功定殖到了马铃薯的芽、根等部位.QHZ11-gfp在根系和匍匐茎的定殖数量均呈现先升高至块茎形成期达到峰值后下降的趋势,并且在整个生育期根系的定殖数量始终大于匍匐茎.菌悬液和生物有机肥处理均显著促进了马铃薯根系的生长,并通过增加株高等农艺性状提高了块茎产量.其中,生物有机肥处理在各部位的荧光强度、定殖数量和对马铃薯的促生效果均显著优于菌悬液.[结论]QHZ11-gfp可在马铃薯植株上成功定殖并对马铃薯有良好的促生效果,将其制成生物有机肥促进了其定殖,使促生效果也更好.

针对马铃薯生产实践中长期单施化肥或化肥过量施用等不合理施肥措施导致土壤碳库活性变差和土壤生物活性降低等问题.通过田间定位试验,分析不同施肥方式:不施肥(CK)、单施化肥(NPK)、单施有机肥(M)、有机无机肥配施(NPKM)对旱作马铃薯农田土壤有机碳组分和碳库管理指数的影响.结果显示,连续施肥5年后添加有机肥的M、NPKM处理较CK和NPK处理显著提高了土壤闭蓄态颗粒有机碳(OPOC)和土壤颗粒态有机碳(POC)含量,降低了土壤矿质结合态有机碳(MOC)含量.与CK和NPK处理相比,M、NPKM处理闭蓄态颗粒有机碳(OPOC)含量分别提高了 32.52％、30.39％和27.09％、24.78％;土壤颗粒态有机碳(POC)含量分别提高了 31.52％、29.65％和25.18％、23.15％.添加有机肥的M和NPKM处理显著提高了颗粒态有机碳(POC)的比例,降低了 MOC的比例,与CK和NPK相比,M、MNPK处理中POC的比例分别增加了 27.72％、25.23％和10.61％、7.54％,MOC的比例分别降低39.42％、33.16％和14.97％、9.81％.添加有机肥显著提高了土壤总有机碳(TOC)、微生物量碳(MBC)、易氧化有机碳(ROC)的含量,与CK处理相比,M和NPKM处理的TOC分别增加了 15.28％和13.64％,MBC增加了21.82％和19.17％,ROC的含量分别增加了 32.45％和31.35％;施用有机肥和有机无机配施均显著提高碳库管理指数(CPMI)较单施化肥分别提高28.8％和35.65％.综上所述,施用有机肥处理(M处理和MNPK处理)显著地提高了马铃薯农田土壤闭蓄态颗粒有机碳(OPOC)、颗粒态有机碳(POC)和总有机碳(TOC)及微生物量碳(MBC)、易氧化有机碳(ROC)含量,提高了土壤碳库管理指数;即马铃薯栽培施用有机肥有利于土壤活性有机碳的积累、能够改变土壤有机碳组分分布特征.