秸秆覆盖与施磷对丘陵旱地小麦产量和磷素吸收利用效应的影响

【目的】冬干春旱、土壤有机质和速效磷缺乏是四川丘陵旱地冬小麦生产的主要限制因素,通过研究休闲期秸秆覆盖还田和施磷对旱地冬小麦产量和磷素吸收利用的影响,以期为四川丘陵旱地小麦高产稳产及磷素高效利用提供技术方案。【方法】试验于2018—2020年在四川仁寿进行,采用裂区设计,以秸秆覆盖（SM）和不覆盖（NSM）为主区;3个磷水平0（P0）、75 kg·hm^-2（P75）和120（P120）kg·hm^-2为副区。分析秸秆覆盖和施磷下小麦干物质积累与转运、产量性状及磷素吸收利用的差异。【结果】秸秆覆盖的增产效应高于施磷效应。2018—2019和2019—2020年度秸秆覆盖处理较不覆盖处理小麦有效穗分别增加17.7%和8.48%,穗粒数增加15.6%和11.2%,产量提高18.6%和13.5%;两年度施磷75 kg·hm^-2较不施磷处理小麦有效穗分别增加18.2%和8.79%,穗粒数增加21.1%和6.09%,产量提高30.2%和16.1%;施磷120 kg·hm^-2比不施磷处理有效穗分别增加21.2%和9.53%,穗粒数增加20.2%和4.03%,产量提高31.8%和17.9%。秸秆覆盖显著提高了小麦开花期和成熟期的干物质、磷素积累量,且均随施磷量的增加而增加;同时秸秆覆盖与施磷均可显著提高小麦花前干物质和磷素转运、花后干物质和磷素积累能力。秸秆覆盖显著提高花前干物质转运量对籽粒的贡献率,但降低了花前磷素转运量对籽粒的贡献率,而施磷显著提高了花前干物质转运量对籽粒的贡献率和花前磷素转运量对籽粒的贡献率。秋闲季秸秆覆盖还田促进了磷的吸收利用,磷肥吸收效率2年分别提高27.3%和23.7%,磷肥偏生产力提高17.8%和14.7%。【结论】秸秆覆盖更有利于促进花前干物质和磷素转运,同时促进花后磷素积累和提高磷肥吸收利用效率,通过增加有效穗和穗粒数实现增产。在本试验条件下,秸秆覆盖+75 kg·hm^-2磷肥是适用于四川丘陵旱地小麦高产高效的耕作栽培措施和磷肥管理方案。     

基于DNA G-四链体的农兽药残留与重金属离子快速检测研究进展

DNA的结构具有多样性,除经典的双螺旋结构外,近年来的研究发现和组装获得了更为多样的DNA结构类型,如三螺旋结构、发夹结构、i-motif结构、G-四链体等非传统结构。这些特殊结构具有一定的功能,例如,G-四链体可与氯高铁血红素结合形成具有辣根过氧化物酶活性的复合物,也可增强某些染料分子的荧光强度。此外,G-四链体的形成与稳定性可控、可设计,是构建化学生物传感的良好材料。以一些典型的研究工作为例,本文对近年来G-四链体在农产品中农兽药残留及重金属离子快速检测中的应用进行了总结,并对其应用前景进行展望。     

近红外光谱法快速测定豆粕蛋白质含量

本文应用近红外分析仪(NZR)测定黄豆粕蛋白质含量。通过对不同蛋白质含量的样品进行光谱扫描,找出最佳吸收波长和校准常数值。21份豆粕样品的测定结果表明,近红外法与经典的凯氏法所测结果呈密切的线性相关(R=0.91),标准偏差为0.5％,无显著性差异。     

营养元素对连作大豆减产的控制功能

通过实验室和田间微区试验方法，连续三年研究结果表明：连作大豆在受到有害生物危害和大豆残茬腐解物中间产物的毒害抑制时，其根系的吸收和运输营养物质及固氮能力均减弱或部分丧失。此时，增加营养元素在土壤中浓度，可达到胁迫吸收的功效，弥补损失。连作大豆增施氮肥，可比不施氮最高增产97．7％。经不施磷最高可增产89％；施钾与不施钾比，最高增产可达26％。施用微量元素，亦能提高产量，与对照相比，施锌增产16．9％，施锰增产13．2％，施硼增产1．4％，施钼增产4．6％，施镁增产14．6％。     

Experimental evaluation of low head oxygenators

The overall mass transfer coefficient, G₂₀, for a single hole orifice plate was evaluated in a series of experiments as affected by four geometric variables: orifice plate hole diameter (5, 10, 14, 19, and 22 mm), hydraulic head on the flooded plate (2.5, 5, and 13 cm), water fall height from the orifice to the receiving pool of water (30, 61, 91, and 122 cm), and the collection pool depth (2.5, 8, 13, 25, and 41 cm). This is, in essence, the simplest form of a low head oxygenator (LHO). A regression equation was developed to predict G₂₀ as a function of these variables, their interactions, and squared terms. The hydraulic head above the flooded plate had no significant effect (P<0.10) on the overall mass transfer coefficient. It was determined that the contribution of the orifice hole solely to overall gas transfer was much less than previously assumed, suggesting that a much larger percentage of gas transfer is due to the splashing and subsequent entrainment as water droplets fall into the receiving pool of water. Practical implications of the results are discussed.     

3种重金属离子对中华绒螯蟹鳃丝Na↑（+）-K↑（+）-ATPase活性的影响

铜、锌、镉 3种重金属离子对中华绒螯蟹 (Eriocheirsinensis)鳃丝Na -K -ATPase活力具有影响。实验结果表明 :3种重金属离子各处理组中华绒螯蟹鳃丝Na -K -ATPase活力随取样时间的变化显著 (P <0 .0 5 ) ,其影响程度与重金属离子的浓度呈正相关 ,且一直呈现被抑制状态 ,而对照组的变化不显著 (P >0 .0 5 ) ,表现出明显的剂量、时间效应关系。同时在重金属离子作用下 ,鳃丝Na -K -ATPase活力在 2 4h时下降幅度较大 ,2 4h后Na -K -ATPase活力下降缓慢 ,而且在同一取样时间各处理组鳃丝Na -K -ATPase活力差异显著 (P <0 .0 5 )。 3种重金属离子对鳃丝Na -K -ATPase活性的毒性大小依次为 :Cd2 >Cu2 >Zn2 。     

以栉孔扇贝闭壳肌为例的几种DNA提取方法的比较研究

以栉孔扇贝(Chlamys farreri)闭壳肌为试验材料，采用浓盐法、酚抽提法、LiCl法及改进的浓盐法和酚抽提法等提取其DNA，通过紫外吸收值测定及琼脂糖凝胶电泳法对提取的DNA质量进行分析比较。结果表明，这5种方法都能提到DNA，但改进的浓盐法和酚抽提法可将其中的蛋白质及RNA较为有效地除去，得到比较纯净的DNA。     

Effects of metomidate anaesthesia or transfer to pur sea water on plasma parameters in ammonia-exposed Atlantic salmon (Salmo salar L) in sea water

Atlantic salmon (Salmo salar L) postsmolts weighing 150 ± 53 g were exposed to 14–15 mg l^–1 TA-N (total ammonia-N) in sea water in 1 m³ tanks for 24h. Blood samples were then taken A) immediately after the fish were netted from the exposure tanks and stunned by a blow to the head; B) 2–20 min after the fish were transferred to 15 l of an anaesthetic solution of metomidate in ammonia-free sea water; or C) 2–20 min after the fish were transferred to 15 l of ammonia-free sea water. Plasma TA-N level was 18% lower in the anaesthetised fish compared to in the fish sampled directly from the exposure tanks (p 0.05), and accordingly 16% lower in the fish transferred to pure sea water although this difference was not significant (p = 0.07). Plasma glucose level was higher in the fish transferred to pure sea water than in the fish receiving the two other treatments (p 0.05), but plasma urea, osmolality, Na^{+, Cl–, Ca2+ or Mg2+} levels did not vary significantly between the different treatments. Plasma TA-N level increased with time in the fish in the metomidate solution (p 0.02).     

Extracellular fluid volume measurements in tissues of the rainbow trout (Oncorhynchus mykiss)in vivo and their effects on intracellular pH and ion calculations

Extracellular fluid volume (ECFV) estimates were determined in various tissues and whole body of resting, chronically cannulated rainbow trout (Oncorhynchus mykiss). Fish were infused with¹⁴C-inulin,³H-polyethylene glycol (PEG, M.W. 4000),³H-mannitol, or¹⁴C-mannitol, and values of ECFV determined from tissue: plasma water distribution ratios after 6 h or 13 h equilibration. Overall,³H-PEG provided the most conservative and reliable estimates after 13 h equilibration, with ECFV values in the order: brain < white muscle < red muscle < liver < heart < gill tissue.¹⁴C-inulin yielded generally similar values to³H-PEG at 13 h, but probably overestimated ECFV in liver.³H-mannitol and¹⁴C-mannitol spaces were similar to each other and far greater than³H-PEG or¹⁴C-inulin values in most tissues.³H-mannitol values increased significantly between 6 h and 13 h, in contrast to¹⁴C-inulin. Mannitol clearly overestimated ECFV in liver and gill, and probably also heart and whole body, but may have provided more realistic estimates in brain due to better penetration of the blood-brain barrier. The Cl^–/K⁺ space technique overestimated ECFV in gills, but was satisfactory in white muscle. Measurements and model calculations evaluated sources of error in intracellular pH (by¹⁴C-DMO) and ion determinations. Trapped red cells in the gills have negligible influence. Errors in ECFV are much more influential in a tissue with a high ECFV (gills) than a low ECFV (white muscle).³H-PEG is the marker of choice for intracellular pH determinations. However, even when³H-PEG is used, the potential for absolute errors in intracellular ion concentrations remains high.     

银杏活性炭对4种有毒气体和铅镐离子的吸附作用

为了验证银杏活性炭的吸附效果,分别采用静态吸附法和动态吸附法,研究了银杏活性炭对部分有毒气体及铅、镉两种重金属离子的吸附作用.结果表明:银杏活性炭对甲醛、苯、氨气、三氯甲烷这4种气体的吸附能力都较强,其对甲醛的吸附能力最强.吸附率可达到140%;银杏活性炭吸附铅、镉离子的效果也较好,对铅离子的吸附量接近200 mg·g...