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71.
Specific ion effects (Hofmeister effects) have recently attracted the attention of soil scientists, and it has been found that ionic non-classic polarization plays an important role in the specific ion effect in soil. However, this explanation cannot be applied to H+. The aim of this work was to characterize the specific ion effect of H+ on variably charged soil (yellow soil) colloid aggregation. The total average aggregation (TAA) rate, critical coagulation concentration (CCC), activation energy, and zeta potential were used to characterize and compare the specific ion effects of H+, K+, and Na+. Results showed that strong specific ion effects of H+, K+, and Na+ existed in variably charged soil colloid aggregation. The TAA rate, CCC, and activation energy were sensitive to H+, and the addition of a small amount of H+ changed the TAA rate, CCC, and activation energy markedly. The zeta potential results indicated that the specific ion effects of H+, K+, and Na+ on soil colloid aggregation were caused by the specific ion effects of H+, K+, and Na+ on the soil electric field strength. In addition, the origin of the specific ion effect for H+ was its chemical adsorption onto surfaces, while those for alkali cations were non-classic polarization. This study indicated that H+, which occurs naturally in variably charged soils, will dominate variably charged soil colloid aggregation. 相似文献
72.
Lignin-degrading enzymes secreted by white rot fungi play an important role in the degradation of lignin and persistent organic pollutants(POPs).In this study,effect of environmental C/N ratio on the activities of lignin-degrading enzymes,lignin peroxide(Li P)and manganese peroxidase(Mn P),produced by Phanerochaete chrysosporium,a white rot fungus,was investigated.Glucose was used as C source,and ammonium tartrate of different concentrations was used as N source to provide different C/N ratios.Relationships between Li P and Mn P activities and environmental C/N ratio were explored.The results showed that the higher the N source concentration,the faster the mycelium pellets aged.The faster the mycelium dry weight increased,the higher the Li P and Mn P activities.A high C/N ratio was a necessary condition for the secretion of Li P or Mn P.In addition,mycelium dry weight essentially affected enzyme activities.In the 122 C/N ratio and 50 C/N ratio treatments,mycelium dry weight essentially affected Mn P activity and both Li P and Mn P activities,respectively. 相似文献
73.
【目的】秸秆还田方式影响土壤和肥料中养分的有效性,本研究通过比较不同还田方式下水稻产量、氮素吸收利用的差异,为水稻人工插秧和毯苗机插技术选择适宜的秸秆还田方式提供依据。【方法】本试验于2016-2018年在成都温江四川农业大学水稻研究所试验田进行,以籼型三系杂交稻F优498为试验材料,采用两因素裂区设计,主区为秸秆不还田(S0)、覆盖还田(S1)和翻埋还田(S2) 3种还田方式,副区为人工插秧(HT)和毯苗机插(MT) 2种栽插方式,氮肥用量为N 135 kg/hm^2,按基肥∶蘖肥∶促花肥∶保花肥=3∶3∶2∶2的比例施用。磷肥(过磷酸钙)用量为P2O5 90 kg/hm^2,作基肥一次施入;钾肥(氯化钾)用量为K2O 150 kg/hm^2,施用比例为基肥∶穗肥=7∶3。分别于分蘖盛期、拔节期、齐穗期和成熟期采集茎鞘、叶和穗样品测定干物重和氮含量,计算不同时期氮素积累、转运及氮素利用效率。【结果】秸秆还田方式对人工和机械插秧水稻产量、植株氮素积累及氮素利用具有显著影响。1)与S0相比,S1、S2处理提高了水稻产量,抑制了水稻分蘖盛期氮素积累,促进了拔节期至成熟期各器官及植株氮素积累,提高了植株氮含量,S1效果优于S2,且S1提高了氮素茎鞘转运量(44.1%)、茎鞘转运率(10.2%)、叶片转运量(23.5%)和穗氮增加幅度(21.2%),S2仅提高了氮素茎鞘转运量(24.7%)、茎鞘转运率(6.5%)和穗氮增加幅度(16.7%)。氮肥农学效率和氮素回收率表现为S1> S2,但S1、S2氮素的稻谷生产效率均有所降低。2)分蘖盛期至拔节期,HT处理的水稻各器官氮素积累、各时期植株氮素积累、氮素转运和产量均大于MT处理的,氮素回收率则显著低于MT处理的。秸秆还田方式对不同栽插方式氮素积累和转运的影响程度不一,分蘖盛期HT处理的氮素积累以S2处理最小,MT处理则以S1最小。两种栽插方式下拔节期至成熟期氮素积累和转运量、氮肥农学利用率及吸收利用率均以S1处理最大。【结论】从提高水稻产量和氮素利用率来看,人工插秧和毯苗机插均适宜采用小麦秸秆覆盖还田模式,并以覆盖还田结合人工插秧方式为最佳。 相似文献
74.
外源ABA提高甘蓝型油菜抗镉胁迫能力和氮素生理利用效率 总被引:1,自引:0,他引:1
75.
连续秸秆–紫云英协同还田对双季稻产量、养分积累及土壤肥力的影响 总被引:2,自引:1,他引:1
76.
葛藤覆盖对幼龄橡胶园表层土壤理化性状和酶活性的影响 总被引:1,自引:0,他引:1
77.
用宏基因组学方法研究绿肥对水稻根际微生物磷循环功能基因的影响 总被引:1,自引:0,他引:1
79.
玉米黏虫(Mythimna separata)是一种常见的鳞翅目害虫,具有暴发性和迁飞性,对农作物危害严重.虫生真菌是昆虫病原微生物中的最大类群,可以有效地控制自然界中害虫的种群数量.为了防治玉米黏虫和与玉米黏虫相近的草地贪夜蛾,丰富虫生真菌菌种资源,以采自重庆江津高粱地中的玉米黏虫僵虫为实验材料,运用传统培养方法分离鉴定了6株真菌.经过形态学观察和分子生物学鉴定将这6株真菌归类于3个属,分别为镰刀菌属(Fusarium)、青霉属(Penicillium)以及鬼伞属(Coprinellus).虫生真菌能够引发昆虫感染发病,将害虫的种群数量长期控制在较低水平以下,在生物防治方面很有意义.此次分离纯化得到镰刀菌属(Fusarium)和青霉属(Penicillium)的真菌均有潜在的杀虫能力,鬼伞属(Coprinellus)真菌具有防治线虫的潜力,这些真菌对玉米黏虫和草地贪夜蛾的杀虫效果还有待于进一步的实验研究. 相似文献
80.
AIM:To analyze the effect of autophagy on inflammatory response regulated by doxycycline in lipopolysaccharide (LPS)-stimulated THP-1 cells and to investigate its molecular mechanism. METHODS:A human monocyte/macrophage cell line THP-1 was stimulated with LPS to establish an cell model of inflammatory response, and the cells were treated with doxycycline. The cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin-8 (IL-8), in cell culture supernatant were measured by ELISA for evaluating the inflammatory levels. For determining the level of autophagy and its effect on inflammatory cell signaling pathways, the protein levels of LC3B, nuclear factor κB (NF-κB) and phosphorylated mammalian target of rapamycin (p-mTOR) were determined by Western blot. 3-Methyladenine (3-MA), an autophagy inhibitor, and rapamycin, an autophagy inducer, were used to study the effect of autophagy on inflammatory response regulated by doxycycline in LPS-stimulated THP-1 cells. RESULTS:The levels of TNF-α and IL-8 were increased rapidly and peaked at 12 h in LPS-stimulated THP-1 cells (P<0.05). Doxycycline significantly inhibited LPS-induced cytokine production in the THP-1 cells. Doxycycline up-regulated LPS-induced autophagy in THP-1 cells and doxycycline itself was an autophagy inducer. The protein levels of p-mTOR was up-regulated by LPS and down-regulated by doxycycline, suggesting that doxycycline induced autophagy via mTOR-dependent pathway while LPS through mTOR-independent pathway. Further studies showed that the combination of LPS, rapamycin and doxycycline inhibited the protein levels of NF-κB, and rapamycin increased the inhibitory effect of doxycycline on cytokine releases. Conversely, 3-MA, the autophagy inhibitor, attenuated the inhibitory effect of doxycycline on NF-κB and cytokine production. CONCLUSION:Autophagy is involved in the process of doxycycline modulating LPS-induced inflammatory response in the THP-1 cells. 相似文献