Effects of Bio-organic Selenium on Agronomic Economic Traits and Selenium Absorption and Distribution in Rice

Under the same conditions of selenium application and application period,different application concentration treatments were set carry out the field plot experiments. The results showed that different treatments had no effect on the growth and development of rice plants;different treatments had an effect on the economic traits of rice; selenium treatment increased the number of filled grains per panicle,seed setting rate and 1 000-grain weight,thus increasing yield; the level of yield was Se4 > Se3 > Se2 > Se1 > Se0; different treatments had a greater effect on the milled rice rate; selenium treatment increased the milled rice rate; the milled rice rate of Se3 and Se4 treatments were 65% and 64%,respectively,which was significantly higher than that of the control group; the general law of selenium absorption of rice was leaf > stem> rice; the selenium content in leaves,stems and rice of different treatments was the highest in Se3 treatment; both the selenium content of rice( total selenium and organic selenium) and the ratio of organic selenium to total selenium in the selenium treatment met the local food safety standard of Hubei Province Selenium content of Selenium-enriched Foods( DBS42/002-2014); selenium-treated rice plants had a high selenium utilization rate,in the range of 51. 26%-64. 12%,exceeding 50%.

Kinetics of selenium absorption in ligated small intestinal loops of chicks

Selenium(Se)is an essential trace element that has a large number of biological functions for broilers.However,the absorption kinetics of Se from sodium selenite in the small intestine of broilers remains unclear.Therefore,two experiments were conducted with 28-d-old commercial male broilers to study the kinetics of Se absorption in ligated small intestinal segments.In experiment 1,the Se absorption in duodenal,jejunal,and ileal segments at different post-perfusion time points(0,20,40,60,80,100 and 120 min)were compared.In experiment 2,a kinetic study of Se absorption was conducted with the duodenal,jejunal,and ileal loops perfused with solutions containing 0,0.0375,0.075,0.15,0.30,or 0.60μg mL^-1 of Se as sodium selenite,and Se contents in perfusates were determined at 100 min after perfusion.The results from experiment 1 showed that the Se absorption increased in an asymptotic response(P<0.0001)to post-perfusion time within 120 min in all the small intestinal segments,but increased linearly(P<0.0001)at less than 100 min after perfusion in duodenal and ileal segments,while more than 96.0%of the maximum Se absorption occurred at 100 min after perfusion in each small intestinal segment.In experiment 2,there was no difference(P>0.05)in the Se absorption rate among different ligated small intestinal segments perfused with solutions containing 0.0375–0.15μg mL^-1 of Se,however,the Se absorption rate was higher(P<0.05)in the jejunum than that in the duodenum perfused with solutions containing 0.30–0.60μg mL^-1 of Se.The kinetic curves of Se absorption demonstrated that the Se absorption was a saturated carrier-mediated process in the duodenum,and the maximum absorption rate was 1271 pg min^-1 cm^-1;whereas the Se absorptions were a non-saturated diffusion process in the jejunum and ileum,and the diffusive constants were 2107 and 1777 cm2 min^-1,respectively.The results from the present study indicate that the jejunum is the main Se absorption site,and the Se absorption is a saturated carrier-mediated process in the duodenum,but a non-saturated diffusion process in the jejunum and ileum of broilers.

Determination of Trace Selenium in Electrolytic Manganese by Graphite Furnace Atomic Absorption Spectrometry

The effects of four types of graphite tube and five matrix modifiers on the determination of selenium by graphite furnace atomic absorption spectrometry were compared.The results show that platform thermolysis coat graphite tube and magnesium nitrate and cobaltco as matrix modifer can get a high sensitivity and a good recovery.The optimized working conditions and interference in the determination were invesigated.This result is consistent with that of XRF.The recovery is from 100.8 % to102.2 %,the relative standard deviation is from 3.47% to 5.56 % (n=9),and the detection limit of selenium is 378 pg (C=44.5μg/g to 97.3μg/g.).The proposed method can be applied to the rapid determination of selenium in electrolytic manganese.

High-Gain N-Face AlGaN Solar-Blind Avalanche Photodiodes Using a Heterostructure as Separate Absorption and Multiplication Regions

It is well known that -nitride semiconductors can generate the magnitude of MV/cm polarization electric field which is comparable with their ionization electric fields. To take full advantage of the polarization electric field, we design an N-face AlGaN solar-blind avalanche photodiode (APD) with an Al0.45Ga0.55N/Al0.3Ga0.7N heterostructure as separate absorption and multiplication (SAM) regions. The simulation results show that the N-face APDs are more beneficial to improving the avalanche gain and reducing the avalanche breakdown voltage compared with the Ga-face APDs due to the effect of the polarization electric field. Furthermore, the Al0.45Ga0.55N/Al0.3Ga0.7N heterostructure SAM regions used in APDs instead of homogeneous Al0.45Ga0.55N SAM structure can increase significantly avalanche gain because of the increased hole ionization coefficient by using the relatively low Al-content AlGaN in the multiplication region. Meanwhile, a quarter-wave AlGaN/AlN distributed Bragg reflector structure at the bottom of the device is designed to remain a solar-blind characteristic of the heterostructure SAM-APDs.

Effect of Agricultural Land Use Changes on Soil Nutrient Use Efficiency in an Agricultural Area,Beijing,China

Agricultural land use and management practices may affect soil properties,which play a critical role in sustaining crop production.Since the late 1970s,several new agricultural land use types had been introduced in the rural areas of China.The purpose of this study is to evaluate the effect of these land use changes on the soil properties,nu-trient absorption rate,and nutrient use economic efficiency ratio in an agricultural area of Beijing.Specifically,the cropland,the orchard and the vegetable field were examined.Results of this study suggest that land use and farming management practices significantly affect the content of soil organic carbon (SOC),total nitrogen (TN),total phos-phorus (TP),and available phosphorus in the surface layer of 0-25 cm (p<0.05) in the Yanqing Basin,northwestern Beijing.Soil nutrients in each agricultural land use type decrease rapidly with the increasing soil depth.Orchard and vegetable field tend to have higher soil nutrients than the cropland does.However,the soil nutrient-absorption rate (NAR) of the orchard and vegetable field is lower than that of the cropland,even though orchard and vegetable field may provide much higher economic benefit.While increasing SOC,TN,and TP in the orchard and vegetable field by intensive farming may be a valuable option to improve soil quality,potential increase in the risk of nutrient loss,or agricultural non-point source pollution can be a tradeoff if the intensive practices are not managed appropriately.

Nitrogen application levels based on critical nitrogen absorption regulate processing tomatoes productivity, nitrogen uptake, nitrate distributions, and root growth in Xinjiang, China

The unreasonable nitrogen(N)supply and low productivity are the main factors restricting the sustainable development of processing tomatoes.In addition,the mechanism by which the N application strategy affects root growth and nitrate distributions in processing tomatoes remains unclear.In this study,we applied four N application levels to a field(including 0(N0),200(N200),300(N300),and 400(N400)kg/hm^(2))based on the critical N absorption ratio at each growth stage(planting stage to flowering stage:22%;fruit setting stage:24%;red ripening stage:45%;and maturity stage:9%).The results indicated that N300 treatment significantly improved the aboveground dry matter(DM),yield,N uptake,and nitrogen use efficiency(NUE),while N400 treatment increased nitrate nitrogen(NO_(3)^(-)-N)residue in the 20–60 cm soil layer.Temporal variations of total root dry weight(TRDW)and total root length(TRL)showed a single-peak curve.Overall,N300 treatment improved the secondary root parameter of TRDW,while N400 treatment improved the secondary root parameter of TRL.The grey correlation coefficients indicated that root dry weight density(RDWD)in the surface soil(0–20 cm)had the strongest relationship with yield,whereas root length density(RLD)in the middle soil(20–40 cm)had a strong relationship with yield.The path model indicated that N uptake is a crucial factor affecting aboveground DM,TRDW,and yield.The above results indicate that N application levels based on critical N absorption improve the production of processing tomatoes by regulating N uptake and root distribution.Furthermore,the results of this study provide a theoretical basis for precise N management.

Atmospheric NO_2 Concentration Measurements Using Differential Absorption Lidar Technique

Using the Differential Absorption Lidar (DIAL) technique, two types of approaches, namely, reflection from retroreflector / topographic target and backscatter from atmosphere, are available for studying remotely the atmospheric NO, concentration. The Argon ion lidar system at the Indian Institute of Tropical Meteorology (IITM), Pune, India has been used for the measurements by following both the path-averaged and range-resolved approaches. For the former, a topographic target (hill) is used for determining path-averaged surface concentration. In the latter, spectral properties of atmospheric attenuation is used for making range-resolved measurements in the surface layer. The results of the observations collected by following both approaches are presented. The average surface NO2 concentration was found to vary between 0.01 and 0.105 ppm and the range-resolved measurements exhibited higher values suggesting treatment of the lidar data for scattering and extinction effects due to atmospheric aerosols and air molecules, and atmospheric turbulence. Certain modifications that are suggested to the experimental set-up, data acquisition and analysis to improve the measurements are briefly described.

Analysis of Phosphorus Nutrition Efficiency of Soybean Genotypes with Different Phosphorus Efficiency at Blooming Stage under Low Phosphorus Stress

[Objective] This study aimed to investigate the phosphorus nutrition effi- ciency of different soybean genotypes at blooming stage under low phosphorus stress. [Method] By using four ＂low phosphorus efficiency＂ soybean genotypes （D03, D05, D17 and D18） and four ＂high phosphorus efficiency＂ soybean genotypes （D31, D34, D37 and D38） as experimental materials, soil culture experiment was conduct- ed with two treatments of high phosphorus （＋P） and low phosphorus （-P）, to analyze the relationship between phosphorus content, phosphorus uptake, phosphorus use efficiency and phosphorus efficiency of soybean genotypes with different phos- phorus efficiency. [Result] Under low phosphorus conditions, four soybean genotypes with high phosphorus efficiency showed significant advantage in phosphorus uptake at seedling stage, to be specific, D34 showed relatively high phosphorus absorption capacity but no advantage in adaptability of phosphorus use efficiency, while only D37 showed relatively high phosphorus absorption capacity and phosphorus use ca- pacity. Correlation analysis and path analysis showed that the level of phosphorus efficiency of soybean at blooming stage under （-P） and （＋P） treatments was mainly determined by phosphorus absorption capacity, and that under （-P） treatment was significantly greater than （＋P） treatment. Phosphorus uptake and phosphorus use ef- ficiency under （-P） and （＋P） treatments both showed great direct effects on phos- phorus efficiency, and phosphorus uptake made greater contribution; however, the indirect effects were relatively low, Under low phosphorus stress, the mechanisms for various soybean genotypes with high phosphorus efficiency to adapt to low phospho- rus stress were different, and phosphorus absorption efficiency （phosphorus uptake） was the main variation source of the phosphorus efficiency of various soybean genotypes at blooming stage. [Conclusion] This study revealed the contribution made by phosphorus absorption efficiency and phosphorus use efficiency to phosphorus efficiency of soybean.

Augmenting the Heat Sink for Better Heat Dissipation

Heat sinks were invented to absorb heat from an electronic circuit conduct, and then to dissipate or radiate this heat to the surrounding supposedly, ventilated space, at a rate equal to or faster than that of its buildup. Ventilation was not initially recognized as an essential factor to thermal dispersion. However, as electronic circuit-boards continued to heat up, circuit failure became a problem, forcing the inclusion of miniaturized high speed fans. Later, heat sinks with fins and quiet fans were incorporated in most manufactured circuits. Now heat sinks come in the form of a fan with fans made to function as fins to disperse heat. Heat sinks absorb and radiate excess heat from circuit-boards in order to prolong the circuit’s life span. The higher the thermal conductivity of the material used the more efficient and effective the heat sink is. This paper is an attempt to theoretically design a heat sink with a temperature gradient lower than that of the circuit board’s excess heat.

不同施磷水平对甘薯硒吸收、分配和转化的影响

为了探明叶面喷施硒条件土壤施磷对甘薯(Ipomoea batatas(L.)Lam.)硒吸收、分配和转化的影响,于2021和2022年在山东莱阳市开展连续2年的田间试验。采用裂区试验设计,主区纯硒用量分别为0 g hm^(–2)(Se0)和150 g hm^(–2)(Se_(1)),副区P_(2)O_(5)施用量分别为0 kg hm^(–2)(P_(0))、75 kg hm^(–2)(P_(1))、225 kg hm^(–2)(P_(2)),测定甘薯各器官干物质量、总硒和有机硒含量并计算硒利用率。结果表明,施磷可显著增加甘薯不同器官干物质量,施硒对不同器官干物质量的影响不显著。施磷可显著提高甘薯块根中硒含量和硒累积量,与不施磷(P_(0))相比,施用低磷(P_(1))可使施硒条件下块根硒含量和硒累积量平均增加19.54%和27.74%,施用高磷(P_(2))可使施硒条件下块根硒含量和硒累积量平均增加40.24%和52.64%。施硒条件下施磷还可提高甘薯块根中的硒分配率和硒利用率,施用低磷(P_(1))和施用高磷(P_(2))块根硒分配率较不施磷(P_(0))平均提高7.77和12.46个百分点,硒利用率平均提高1.81和3.36个百分点,施磷对甘薯全株硒利用率影响不显著。施磷提高了甘薯块根中总硒含量的同时,还提高了块根中有机硒含量,但对块根中有机硒占总硒的比例影响不显著。综上所述,富硒甘薯生产中,适量增加施磷量可以提高甘薯不同器官干物质量,增加块根中的总硒和有机硒含量,提高硒利用率,但应避免过量施磷带来的环境风险。

富硒食用菌对硒的吸收转化机制及生物功能的研究进展

富硒食用菌含硒多糖、硒蛋白、硒多肽等多种高生物活性成分,但因为种类、硒生物转化方式和栽培技术等因素的差异,其硒形态组成和有机硒转化率不同,使富硒食用菌表现出不同的生物活性和作用机理。因此,了解硒在食用菌内的各种存在形态,跟踪硒在食用菌内的分布、吸收和转化规律,能更有效地将硒转化为易于人体吸收且无毒的有机硒化合物。本文总结并讨论了代表性富硒食用菌中不同形态硒在总硒中的占比、不同形态硒的吸收和转化过程、总硒的阈值、富硒技术的现状以及基于该吸收转化机制和富硒技术带来的产业问题,并从免疫活性、抗肿瘤活性和抗氧化活性的角度综述了富硒食用菌中硒不同转化形态的生物功能。以期为食用菌的精准富硒调控提供参考依据,为高活性的不同形态硒的开发提供科学支撑,并提出了富硒食用菌发展的方向。

施硒对大蒜产量和含硒量的影响

以土壤施硒 (0 .1g·m- 2 )研究大蒜对硒的吸收、转化及硒对大蒜产量的影响。结果表明 ,4个大蒜品种吸收硒的能力为 :应县大蒜 >忻州大蒜 >榆次大蒜和太谷大蒜。以土壤施硒 (0 .0 1、 0 .1、 1、 10g·m- 2 )、叶面施硒 (10、 10 0、 10 0 0mg·kg- 1)和硒浸种 (10、10 0mg·kg- 1) 3种方式处理应县大蒜 ,结果随着硒处理浓度的提高 ,大蒜的产量先升后降 ,大蒜含硒量随着硒处理浓度的提高而提高 。

硒对小白菜生长和养分吸收的影响

以小白菜为材料 ,研究了硒对植株生长和养分吸收的影响。结果表明 ,当营养液中加入低浓度硒 (Se≤ 1.0mg L)时促进了小白菜的生长 ,增加了产量 ;加高浓度硒 (Se≥ 2 .5mg L)时则抑制了小白菜的生长。加硒后增加了小白菜地上部可溶性总糖、还原糖含量 ;降低了蔗糖和淀粉的含量 ;低浓度硒增加了粗纤维含量 ,而高浓度硒则降低了其含量 ;Se≤ 1.0mg L的硒处理降低了植株地上部总蛋白质的含量 ,但随着硒浓度的进一步增加 (Se >1.0mg L)植株体内的总蛋白质含量逐渐升高 ,并大于对照。加硒后增加了小白菜地上部游离氨基酸总量和N、Ca、Mg、Mn、Zn含量 ,降低了P、K、S元素的含量 ;与对照相比 ,加硒后增加了小白菜地下部N、S元素的含量 ,降低了P、Ca、Mg、Fe、Mn、Zn元素的含量 ,但对K元素的影响不大。无论是小白菜地上部还是地下部 ,体内硒的含量均与营养液中硒的浓度呈显著的正相关。植物地上部硒的含量以有机态硒为主 ,有机硒转化率均在 80 %以上。

不同价态外源硒对小白菜生长及养分吸收的影响

通过盆栽试验,研究了土壤外源加入两种不同价态的硒[Se(Ⅳ)和Se(Ⅵ)]对小白菜生长、营养元素和硒吸收的影响。结果表明,施硒对小白菜的生长均表现出低浓度(<5 mg/kg)促进,高浓度(>5 mg/kg)抑制的趋势。Se(Ⅵ)处理小白菜地上部硒含量大于地下部;而Se(Ⅳ)处理则相反。硒从根部转运到地上部的转移因子表现为Se(Ⅵ)处理大于Se(Ⅳ)处理。两种价态硒处理,小白菜对氮、磷、钾、硫、镁和锌的吸收也表现出低浓度时为促进,高浓度时为抑制的趋势。Se(Ⅵ)显著增加了钙的吸收,Se(Ⅳ)却无显著影响;Se(Ⅳ)和Se(Ⅵ)均能促进小白菜对铁的吸收。相同浓度下,Se(Ⅵ)对各种营养元素吸收的影响显著大于Se(Ⅳ)。综合硒对生长和养分吸收的影响看出,小白菜施硒量以Se(Ⅵ)不超过2.5 mg/kg或Se(Ⅳ)不超过5 mg/kg为宜。

施用氨基酸硒肥对梨体内硒含量的影响

【目的】以华酥梨为试材,研究了不同施肥方式施用氨基酸硒肥对梨体内硒含量的影响,以期为氨基酸硒肥的合理施用及富硒梨生产提供理论依据。【方法】试验设置叶面喷施和土壤施入两种施肥方式,每种施肥方式设置4个处理,其中土壤施入设每株施入30 m L(900 mg/plant)、60 m L(1800 mg/plant)、90 m L(2700 mg/plant)和120m L(3600 mg/plant),叶面喷施设每株喷施300倍(150.0 mg/plant)、400倍(112.5 mg/plant)、600倍(75.0mg/plant)和1000倍(45.0 mg/plant)。叶面喷施从盛花期开始,每隔15天喷施一次,直至果实成熟前15天左右停止,共喷施7次。土壤施入前将氨基酸硒肥兑清水,均匀浇于施肥坑中,于盛花期一次性施入。分别于花后15 d、30 d、45 d、60 d、75 d、90 d取果实和叶片,并将果实解析为果皮、果肉和果心3个部分,分别测定硒含量。【结果】1)两种施肥方式均可极显著提高梨果实和叶片中的硒含量。2)喷施氨基酸硒肥后梨果实和叶片中硒含量在发育初期最高,不同部位硒含量的变化趋势不同,而土施氨基酸硒肥后梨果实和叶片中硒含量均呈现逐步升高的趋势,并在采收时达到最高。3)施肥后单果硒吸收量呈现上升的趋势,花后30 45 d为果实吸收硒的关键期。4)梨叶片的硒含量高于果肉,而且含量高低顺序不受施肥的影响,但果皮、果肉和果心3个部位硒含量的高低顺序与施肥方式有关,喷施氨基酸硒肥可以改变硒在果实各部位含量的高低顺序,而土施氨基酸硒肥对其没有影响。5)施肥量较小时,果肉和叶片中硒含量与施肥量呈正相关,但当施肥时有效硒含量超过2700 mg/plant时,硒含量反而会下降。【结论】施用氨基酸硒肥影响着梨树体内硒含量。与土施相比,喷施处理后梨对硒的吸收快、吸收和积累效率高、硒利用率高,因此,喷施氨基酸硒肥是富硒梨生产最经济有效的方法,施肥量以有效硒含量不超过2700mg/plant为宜。

葡萄对硒的吸收、分布和积累特性的初步研究

研究葡萄(Vitis vinifera‘Red Globe’/V.vulpina‘Beta’)对硒的吸收、分布和积累特性及硒对葡萄品质的影响。结果表明:在不施硒的条件下,葡萄体内的硒含量很低,硒的累积顺序为根>叶>新梢>主蔓>果实,果实中的含硒量只有0.009mg.kg-1DM。根际施用0.5、1.0、1.5kg.hm-2亚硒酸钠后,葡萄各部位的含硒量均显著提高,并且各部位的含硒量与土壤施硒量呈显著的正相关。施硒后,硒在葡萄植株体内的分布发生变化,各部位累积量的顺序为叶>根>新梢>果实>主蔓,果实中含硒量达到0.062mg.kg-1DM。在整个生长发育过程中,果实含硒量没有明显的变化,单果硒总量一直处于升高的趋势,至花后90d达到最高值,成熟期含硒量降低。不同浓度硒处理除了0.5kg.hm-2亚硒酸钠处理外均可显著提高果实可溶性固形物含量,对单果鲜质量、单果干质量、可滴定酸没有明显的影响。

施硒对茄子吸收转化硒和品质的影响

盆栽试验结果表明,土壤施硒(0 15、0 60、3 00mg/kg)条件下,茄子的含硒量随施硒量的增加而显著增加。当施硒量为0 60和3 00mg/kg时,茄子无机硒转化成有机硒的比率下降,显著提高了茄子粗蛋白、粗脂肪和还原糖含量,增加了茄子的必需氨基酸总量,改善了茄子的品质。土壤施硒显著增加了茄子蛋氨酸、胱氨酸和丝氨酸的含量,但谷氨酸和脯氨酸的含量显著降低。

土壤—植物系统中硒营养的研究进展

硒作为人类和动物的必需微量元素之一,也是植物生长发育不可缺少的营养元素,但硒缺乏和硒污染均会对生态环境和人类健康造成严重威胁。文章从硒的生物学功能、硒在人体中的作用及其含量安全标准、土壤中硒的含量及有效性、植物中硒的含量及吸收转运、硒与磷、硫的营养关系等进行综述,提出今后应加强土壤硒形态及形态转变、硒蛋白及含硒氨基酸分离和纯化、植物体内硒的生理生化作用机制及农作物富硒机理研究;同时,应从筛选富硒突变体入手,优选出富硒的植物新品种,为更好地开发和利用硒资源提供参考依据。

富硒小麦提取物中硒含量及其抗氧化特性

为研究富硒小麦的富硒水平和硒的赋存形态,选用兰州高硒地区生产的富硒小麦为原料,通过超声、离心、透析的方法将富硒小麦中的有机硒和无机硒分离,用火焰原子吸收光谱法测定小麦硒水平。结果表明,富硒小麦硒的主要赋存形态是有机态,占总硒的84.36%。有机态硒主要为硒蛋白(54.46%),硒多糖次之,少量为硒核酸和其他有机态硒。在蛋白态硒中,清蛋白和谷蛋白硒含量较高,分别占总硒的19.46%和16.83%。抗氧化性分析结果表明,多糖相对于蛋白和核酸提取物,具有更长的诱导时间、更高的1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除能力和Fe3+还原力。皮尔逊相关性分析表明,小麦富硒提取物抗氧化能力与其硒含量之间表现为显著的正相关性。

交联壳聚糖在硒的形态分析中的应用研究

本文研究了交联壳聚糖对Ｓｅ（Ⅳ）和Ｓｅ（Ⅵ）的吸附行为，并对吸附机理进行了探讨。结果表明：在ｐＨ＝４时，Ｓｅ（Ⅳ）的吸附率达９５％，而对Ｓｅ（Ⅳ）几乎无吸附；吸附Ｓｅ（Ⅵ）后，用１ｍｏｌ／Ｌ盐酸定量解吸，建立了氢化物发生原子吸收测定环境中痕量Ｓｅ（Ⅳ）／Ｓｅ（Ⅵ）和有机硒的方法。本法的检出限为２０ｎｇ／Ｌ，回收率为９３％～１０６％，变异系数为２．０％～５．０％。