黄腐酸(FA)旱地龙在苹果节水生产中的应用效果研究

该文通过正交试验，探讨了在有限灌水条件下黄腐酸类抗旱剂FA旱地龙对果树的生长发育、保墒能力、果实品质及产量的影响。研究结果表明：果树施用FA旱地龙后，有抗旱增产效果，增产幅度可达4.88%～7.32%，平均单果质量增加4.2%～8.4%，并且使果实品质得到改善；与充分灌溉条件相比，水分利用效率也有所提高，每hm²节约灌溉水量487.5 m³。同时，该文还在分析本地区各降水年型水分盈亏特点的基础上，探讨了不同降水年型下FA旱地龙的最佳喷施次数和喷施时间。     

Use of the fluorescent antibody technique to characterize equilibrium survival concentrations of Bradyrhizobium japonicum strains in soil

Summary The ability of Bradyrhizobium strains to survive saprophytically in soil was studied by means of fluorescent antibodies (FA). It was found that the recovery rate may be considered a constant value although the limit of detection by the FA technique is approximately 10³ bacteria g^–1 soil. By studying the survival kinetics of B. japonicum strains introduced into soils, we observed that whichever soil-strain combination was tested in a given soil during the incubation all the different populations of a strain reached the same survival balance level, generally about 10³–10⁴ Bradyrhizobium g^–1 soil. When we reintroduced strains into a soil containing rhizobia of the same specificity, the new inhabitants reached the same equilibrium level as that of the initial population. The balance threshold level does not appear to be a very sensitive way to classify, strains on their saprophytic ability. We suggest that survival kinetics should be characterized by the rate at which the population reaches equilibrium.     

Measuring soil disturbance effects and assessing soil restoration success by examining distributions of soil properties

Successful restoration of an ecosystem following disturbance is typically assessed according to similarity between the restored site and a relatively undisturbed reference area. While most comparisons use the average or mean parameter to represent measured properties, other aspects of the distribution, including the variance of the properties may assist in a more robust assessment of site recovery. Our purpose was to compare soil properties in different ages of reclaimed soils with those in reference areas by incorporating the potentially different distributions according to areas. On two sampling dates, in consecutive years, we examined soil properties on a chronosequence of reclaimed natural gas pipelines spanning recovery ages of <1–54 years, obtaining data on soil moisture, organic carbon, nitrogen, electrical conductivity, pH, and microbial abundance. To make the comparisons, we analyzed our data with a Bayesian hierarchical linear mixed model and obtained posterior predictive distributions for the soil properties. This allowed us to probabilistically quantify the extent to which a soil property from a reclaimed treatment was similar to that from an undisturbed reference. We found that the posterior predictive variance of most soil properties was particularly sensitive to disturbance and reclamation, especially, within the first few years of recovery. Response of this variance to disturbance, reclamation, and recovery was not necessarily accompanied by a shift in the posterior predictive mean value of the property. Patterns for all soil properties changed over time, with posterior predictive distributions of soil properties generally becoming more similar to those of the undisturbed reference sites as recovery time increased. We suspect these trends in altered variability coincide with the degree of spatial heterogeneity in soil properties that results following disturbance and reclamation, which is also coupled to patterns of vegetation recovery.     

黄腐酸对油菜种子萌发、氮素吸收及抗寒性的生理效应

研究表明,黄腐酸（ＦＡ）浸种可有效激活油菜种子萌发过程中蛋白酶、肽酶和酸性磷酸酯酶活性,提高种子发芽指数和活力指数,增强幼苗硝酸还原酶活性,促进氮素吸收。在低温胁迫条件下,黄腐酸可增强油菜幼苗超氧物歧化酶（ＳＯＤ）、过氧化氢酶（ＣＡＴ）活性　和提高抗坏血酸含量,抑制丙二醛（ＭＤＡ）的产生,减少细胞电解质渗漏,减轻叶绿素的破坏,维护细胞的生理功能,光合速率和根系活力增加,呼吸速率明显降低。     

溶解性富里酸对土壤中多环芳烃迁移的影响

多数多环芳烃（PAHs）因其水溶性低,且易被土壤有机质固持,曾经被认为其迁移能力十分微弱。但土壤中溶解性有机质可能影响PAHs的溶解、吸附等环境过程,进而影响其迁移性。本文旨在研究富里酸提取的溶解性有机质（FDOM）对PAHs在土－水间迁移的影响及其可能机制。溶液化学稳定性研究结果显示,FDOM在溶液pH 2.0～7.0、CaCl₂浓度0～1 500 mmol L^-1范围内均能保持较好的分散性,未发生絮凝沉淀。室内土柱淋溶试验结果表明,FDOM在土壤中具有较强的迁移能力,在FDOM持续淋溶条件下,菲、芘以及苯并[a]芘在淋出液中的浓度明显提高,并有少量二苯并[a, h]蒽淋出。FDOM淋溶处理的土柱表层土壤中菲、芘、苯并[a]芘和二苯并[a, h]蒽的淋失率分别为92.06%、92.07%、84.52%和23.27%,显著高于对照组（p<0.05）。以上研究结果表明,FDOM可作为载体提高PAHs在土壤中的迁移性,增加PAHs向深层土壤和地下水迁移的可能性。     

地表水中有机物的氯化活性研究

本文考察了不同种类天然有机物氯化消毒时生成消毒副产物情况。利用一系列的树脂,将地表水中的腐殖质进行富集和分类,得到天然水体中的富里酸和胡敏酸,富集结果发现在地表水的腐殖质中以富里酸为主,含量为83%。将富集到的富里酸和胡敏酸分别进行氯化处理,用电子捕获气相色谱仪测定消毒副产物。结果发现,相同底物浓度,相同消毒剂投量,富里酸氯化生成的消毒副产物要高于胡敏酸的,表明地表水体中富里酸是主要的消毒副产物的前驱物质。     

FA旱地龙对寒地大田作物增产的研究

研究了ＦＡ旱地龙对玉米、大豆的增产作用。结果表明,用３００倍液喷施玉米、大豆,可玉米增产１２．９％,大豆产量增加１３．５％。     

Spectroscopic Characterization of Fulvic Acid Under Different Cover Crop Systems

Abstract

Fulvic acids (FAs) are an important dynamic component of soils that may be affected by soil management. Carbon‐13 cross‐polarization total sideband suppression nuclear magnetic resonance (CP‐TOSS ¹³C NMR) was used to examine the effect of cover crop systems on the characteristics of fulvic acid fractions. FA was isolated from soils with the following treatments: 1) vetch/rye, 2) rye alone, and 3) check (no cover crops) with varying nitrogen fertilizers. Preliminary NMR results indicate that FA from the rye alone system both with and without nitrogen fertilizers contains less aliphatic carbon (0–108 ppm) than that from the other two treatments. Based on the elemental composition analysis result, C∶N ratio of FA from rye alone cover with or without nitrogen fertilizer is lower than FA from vetch/rye cover system. These data suggest that farming systems affect the FA compositions.