控释碘肥对生菜富碘及若干生理特性的影响

通过温室盆栽试验,以普通碘肥为对照,研究了包膜控释碘肥对生菜富碘及某些生理特性的影响。结果表明, 施碘处理与不施碘相比显著提高生菜叶片的碘含量。在两种施碘水平下（I 10和20 mg/kg,土）,与普通碘肥相比,控释碘酸钾和控释碘化钾均显著提高生菜叶片的碘含量,分别提高了46.60%~61.16%、 46.59%~58.53%; 同时提高了生菜生物量、 叶片叶绿素含量、 维生素C含量及抗氧化酶活性［超氧化物歧化酶（SOD）、 过氧化物酶（POD）和过氧化氢酶（CAT）］,降低了生菜叶片硝态氮和丙二醛（MDA）含量; 碘酸根离子处理的土壤碘的淋失率高于碘离子处理; 施用控释碘酸钾和控释碘化钾后,土壤淋溶液中碘淋失量峰值出现时间延后,碘淋失率较普通碘肥分别降低了45.99%~50.97%、 39.18%~46.29%,差异显著。碘肥用量试验的结果表明,与施碘10 mg/kg相比,施碘20 mg/kg时显著提高了生菜叶片的碘含量,但对生菜品质及生理指标无显著影响。与普通碘肥相比,控释碘肥不仅显著提高了生菜叶片对碘的富集,还减少了碘素从土壤中的流失量,提高了碘肥的利用率。施用控释碘肥是培育富碘蔬菜的有效途径之一。     

生物炭与叶面硒肥联合施用对生菜吸收镉及土壤镉形态的影响

  目的  为探明生菜吸收富集镉的能力对生物炭与叶面硒肥的响应程度,抑制有毒有害元素镉的吸收。  方法  通过盆栽试验,以生菜为研究对象,在镉污染土壤中添加生物炭,并在生菜叶片上喷硒处理,探索了生物炭与叶面喷硒的联合施用对镉污染土壤理化指标（pH和有机碳）和土壤不同形态镉含量以及对生菜镉吸收累积的影响。  结果  ① 土壤中添加生物炭与叶面硒肥都可以有效降低生菜可食部镉含量,其中喷施低浓度硒的效果更好。当生物炭添加量为30 g kg?1,叶面喷硒浓度为1 mg L?1时,生菜地上部镉含量由0.314 mg kg?1降至0.049 mg kg?1,低于国家食品安全标准（GB 2762—2017）中规定的叶菜类镉限量值0.20 mg kg?1。② 镉胁迫下,添加生物炭与叶面硒肥的交互作用对生菜镉含量和镉富集与转运能力均产生了显著性的影响,相对于生菜根部镉含量,添加生物炭的效应高于叶面硒肥的效应,而对于地上部镉含量,叶面硒肥的效应高于添加生物炭的效应。③ 生物炭添加可通过改善土壤pH和有机碳含量降低酸可提取态、可还原态、可氧化态镉的比例,增加残渣态镉的比例,从而有效地降低生菜对土壤中镉的吸收累积,减少生菜中镉含量。  结论  综合来看,生物炭与叶面硒肥联合施用可以降低生菜镉含量,其效果明显高于两者单独施用的效果,为无公害蔬菜的种植提供理论指导。     

我国富硒农产品与土壤标准研究

硒是人和动物生命活动必需的微量元素,缺硒可影响人体健康并导致诸多疾病。通过富硒农产品补硒是一种简单而有效的方法。本文从硒对人体的健康功效、居民硒的摄入量状况、土壤硒分布与作物硒吸收特征、富硒土壤研究现状、富硒农产品标准、富硒农产品中硒摄入量安全性评估等方面,进行了系统研究,阐述了研制富硒土壤分类标准的必要性。     

4种蔬菜对硒酸盐的吸收、富集与转运特征的研究

用盆栽试验研究了不同含量硒酸钠对4种蔬菜（小白菜、芥菜、生菜和菠菜）生长、硒吸收及转运特征的影响,为富硒蔬菜的开发和硒污染土壤的植物修复提供理论依据。结果表明,低含量的硒酸钠态硒（〈1.45mg·kg-1）可促进4种蔬菜的根和茎的生长,增加其生物量,但过量硒酸态硒（〉2.04mg·kg-1）对蔬菜有明显的毒害作用。供试的4种蔬菜地上、地下部硒含量均随外源硒含量的增加显著增大（P〈0.01）,其中小白菜和芥菜地上硒含量是生菜和菠菜的5.8～8.5倍;4种蔬菜地下部硒含量的大小依次为芥菜〉小白菜〉菠菜〉生菜。所有施硒处理小白菜、芥菜和生菜地上硒含量约是地下硒含量的1～2倍,菠菜地上与地下硒含量与土壤硒含量高低有关,当土壤硒含量〈5.02mg·kg-1时,菠菜的地下硒含量大于地上部,当土壤中硒含量〉5.02mg·kg-1时,地上部硒含量大于地下部。4种蔬菜相比较,地上部硒富集系数（BCFshoot/soi）l值的大小依次为小白菜≈芥菜〉菠菜〉生菜,地下部富集系数（BCFroot/soi）l值的大小依次为芥菜〉小白菜〉菠菜〉生菜;以小白菜对硒的转运系数（TF）值最大,菠菜最小。供试的4种蔬菜中,小白菜因具有较高的将六价硒从地下转运到地上的能力,且拥有较高的地上生物量,可作为富硒蔬菜和硒污染土壤修复植物。     

叶面喷施锌或硒对生菜吸收镉的拮抗作用研究

环境污染导致水和土壤中镉等重金属元素超标，是多年来造成农产品质量不合格的重要原因之一。农作物中的重金属元素最终会通过食物链进入人体，对人体造成危害。因此研究如何抑制农作物对镉的吸收在理论上和应用上都有重大意义，前人也做了一些相关的工作。众所周知，硒和锌是对人体有益的微量元素。缺硒会得各种各样的疾病，研究还表明硒具有抗癌作用，近年来人们对富硒食品做了大量的研究；锌是许多金属酶的重要组成部分，并能激活多种酶，因此锌在生物的正常代谢过程中起着重要作用。当镉与锌、硒共存的时候，它们之间有复杂的相互作用。     

L-半胱氨酸对水稻根系吸收亚硒酸盐的影响

硒是人和动物体内必需的微量营养元素。许多地方性疾病如克山病、大骨节病等均与环境中硒水平低有关[1]。硒对人和动物健康从有益到有害的范围很窄[2-4],摄入过量硒会引起人畜中毒[5-6]。由于人体内的硒主要通过植物性食物获得[7-8],因此探讨根外环境中影响植物吸收硒的因素,进一步通过施肥措施调节植物对硒的吸收以及调控植物性产品可食部分硒含量,确保食用安全和人体健康是非常必要的。在土壤中,硒主要以元素硒(Se0)、硒化物(Se2-)、亚硒酸盐(SeO32-)、硒酸盐(SeO42-)和有机态硒[(CH3)Se]五种形态存在。其中可以被植物根系直接吸收利用的无机硒主要有硒酸盐和亚硒酸盐[8]。研究表     

硒在动植物及微生物体中的转化规律研究进展

我国低硒地区占国土总面积的72%,其中严重缺硒地区的粮食等天然食物硒含量较低,当地人因无法从食物中摄取足够硒而罹患多种疾病。因此,通过科学手段有效解决我国人体缺硒问题意义非凡。植物性食物是动物和人体碳水化合物及矿物质等营养的重要来源,植物吸收环境中的硒,并将其转化为有机态硒,之后通过食物链为人体吸收利用,这是一种安全有效的缓解人体硒摄入匮乏的途径。植物生长过程中所需的矿物质营养大多都来自于土壤,微生物作为土壤中广泛存在的一种生物,不仅在植物促生方面发挥着重要作用,而且还可通过生物活化等作用,将土壤中的硒转化为有利于植物吸收的形态,进而提高植物对硒的利用率。本文综述了目前关于动物、植物、微生物对硒转化利用规律方面的研究进展,以期为今后通过微生物介导途径,提高植物吸收转化环境硒的效率,改善动物及人体缺硒状况,进而解决缺硒地区人体健康问题提供有价值的参考信息。     

番茄幼苗对硒的吸收与硫营养的关系

低浓度硒(<0.1ppm)促进番茄幼苗生长,高浓度硒抑制番茄幼苗生长,浓度愈高抑制愈强。硫降低硒对植物的毒害。番茄幼苗吸收硒后,以根积累最多,硒在各部位的分布顺序为根>茎>叶_4>叶_3>叶_2>叶_1。不同天数硫饥饿处理都促进番茄幼苗根对硒的吸收和运转,增加植株各部位的含硒量,其中以硫饥饿6天的效果最佳。     

影响作物吸收硒的土肥因素研究进展

硒是人体的必需元素,硒缺乏会造成多种疾病。通过摄入农产品适量补充硒,能保证人体健康。对作物补充适量硒肥,是增加农产品硒含量的有效措施。作物吸收硒与土壤因素及肥料因素关系密切,判断哪个因素是影响作物吸收硒最关键的因素值得探讨。通过对文献系统调研发现,影响作物吸收硒的土肥因素中,土壤本身的硒含量及硒肥量最关键,土壤pH及有机质含量为活化土壤硒的间接因素,硒肥种类及施肥方式为配合硒肥量的补充因素。促进作物对硒的吸收要结合土壤性质、硒肥量、施肥方式等因素综合考虑,以达到富硒农产品高产高效的目的。     

土壤镉污染条件下叶面硒肥对生菜镉积累的影响

为探讨叶面硒肥对生菜(Lactuca sativa L.)镉胁迫的改善作用,通过盆栽试验,设置2个镉污染浓度(1 mg/kg,Cd1;3 mg/kg,Cd3)和3个叶面硒肥浓度(0 mg/L,Se0;1 mg/L,Se1;3 mg/L,Se3),研究了不同浓度叶面硒肥对生菜镉积累的影响。结果表明:①叶面硒肥的喷施可不同程度降低生菜对镉的吸收积累,较之Cd1+Se0处理,Cd1+Se1处理可显著降低生菜叶镉含量,降幅为26.29%;较之Cd3+Se0处理,Cd3+Se3处理下生菜叶镉含量显著降低49.05%。②喷施适宜浓度的叶面硒肥可不同程度提升生菜过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性,降低丙二醛(MDA)含量,Cd1+Se1处理下,生菜的CAT、SOD活性分别显著高于Cd1+Se0处理40.38%、68.71%,而MDA含量则显著降低44.48%;Cd3+Se3处理下,生菜的CAT、SOD活性较Cd3+Se0处理分别显著提升77.48%、51.70%,而MDA含量则显著降低48.90%。因此,喷施适量的叶面硒肥可明显提升生菜抗逆特性,进而有效阻控生菜对镉的吸收,其中土壤镉含量为1 mg/kg(Cd1)时,叶面硒肥喷施浓度以 1 mg/L效果最佳,土壤镉含量为3 mg/kg(Cd3)时,叶面硒肥喷施浓度以 3 mg/L效果为最优。     

Preparation of Titanate Whiskers Starting from Metatitanic Acid and Their Adsorption Performances for Cu(II), Pb(II), and Cr(III) Ions

The accumulation of metals and nutrients in biosolid-amended soils and the risk of their excess uptake by plants is a topic of great concern. This study examines the elemental uptake and accumulation in five vegetable plants grown on biosolid-applied soils and the use of spectral reflectance to monitor the resulting plant stress. Soil, shoot, root, and fruit samples were collected and analyzed for several elemental concentrations. The chemical concentrations in soils and all the plant parts increased with increase in applied biosolid concentrations. The Cu and Zn concentrations in the plant shoots increased in the order of collard?<?radish?<?lettuce?<?tomato?<?pepper. The Cu and Zn concentrations accumulated significantly in the fruits of the tomato plants compared to other plants. Among all the plants, the shoot concentration factor (SCF) of Zn was significantly higher for pepper plants, indicating increase in uptake of Zn. The shoot relative uptake index (SRUI) of Cu and Zn increased in the order of collard?<?radish?<?lettuce?<?tomato?<?pepper. The shoot dry weight and spectral reflectance of the radish plants in the near-infrared (NIR) region (800–1,300 nm) decreased significantly with increase in biosolid concentration compared to other plants. Increase in plant stress with increase in biosolid dose was evident in radish plants through significant reduction in Normalized Difference Vegetative Index (NDVI). This study indicates the potential use of spectral reflectance as a tool for the screening and monitoring of stress-sensitive plant species and their physiology and as a result, indirectly assesses the chemical concentrations in soils and plants.     

Nitrogen and water uptake patterns and growth of plants at various minimum solution nitrate concentrations

Increasing fertilizer and energy costs, as well as awareness of environmental quality, require greater fertilizer use efficiency. Providing plant nutrients in the quantity and at the time needed, possibly through fertigation, should lead to more efficient fertilizer use. Knowledge on crop nutrient requirements and minimum nutrient concentrations in the root zone at different stages of growth is important. Hydroponic greenhouse experiments were conducted using tomato and lettuce plants to determine minimum solution nitrogen concentrations which would allow maximum plant growth for a system of frequent nitrogen application and to quantitatively measure nitrogen uptake rates as a function of time. Minimum N levels for the tomato experiment were 2, 10, and 20 mg/1. Solutions were analyzed three times a week to determine N uptake and sufficient KNO₃ was added each time to supply the plant N demand so that the targeted minimum N concentration would be achieved at the next sampling time. The minimum N concentrations in the lettuce trial were 5, 10, 20 and 50 mg/1. A control consisting of 105 mg/1 N was used for both crops. There was no significant effect of N concentration on N uptake throughout the experiment for lettuce and during the early stages of tomato growth. Higher N uptake during the latter stages of tomato growth occurred for the control as compared to the other treatments. The latter observation was probably caused by N diffusion gradient development because of the dense root system and inadequate solution stirring. Plant growth results were comparable to N uptake results. The ratio of N to water uptake was fairly constant throughout the growth period with a trend toward decrease in the ratio with time for tomatoes. Low N concentrations can occur at the root surface without limiting plant growth.     

Factors influencing the efficacy of iodine foliar sprays used for biofortifying butterhead lettuce (Lactuca sativa)

Iodine biofortification of butterhead lettuce (Lactuca sativa) via foliar sprays was investigated in field trials, focusing on assessing the influence of the time and application method. The iodine (I) concentrations in the edible plant parts increased when potassium iodide (KI) and potassium iodate (KIO₃) solutions were sprayed at doses up to 0.25 kg I ha^?1 on different dates close to harvest. Crop yield and marketable quality were not significantly affected by I treatments. A greater efficacy of KI was frequently observed and probably related to its lower point of deliquescence and smaller anion size in comparison with KIO₃. KI sprays on butterhead lettuce at different times of the day resulted in a higher I enrichment when applied at 11:00 and 15:00 h. The diurnal variation in I uptake may reflect the impact of fluctuating climatic conditions at the time of application. Iodine treatments at different application dates near harvest led to an increasing I concentration in the vegetable produce that could be related to the rising shoot fresh mass and leaf area. When KI and KIO₃ were sprayed simultaneously with commercial calcium fertilizers, fungicides or insecticides, I accumulation in butterhead lettuce was not negatively affected or in some cases even significantly enhanced. The results show that foliar sprays of KI and KIO₃ are an effective method to biofortify butterhead lettuce with I and this approach may easily be implemented as a routine method in commercial cultivation.     

秸秆钾替代化肥钾对莴笋的营养效应研究

在重庆地区多年种植蔬菜的两个基地进行田间试验,研究了秸秆钾替代化肥钾对莴笋的产量、品质、养分吸收量和钾素利用率的影响。秸秆钾替代化肥钾较无钾肥处理极显著提高两个试验点莴笋产量,增产11.4%~13.7%和11.4%~15.3%,各处理产量大小为:MH+KL(有机肥钾50%+化肥钾50%)MM+KM(有机肥钾30%+化肥钾70%)ML+KH(有机肥钾10%+化肥钾90%)CK2(常规施钾处理)CK1(无钾肥处理),以高量(50%)秸秆钾处理(MH+KL)增产作用最大。秸秆钾替代化肥钾较常规施钾提高莴笋产量,但增产作用不显著。两个试验点秸秆钾替代化肥钾显著降低莴笋叶维生素C和可溶性糖含量,降幅分别为4.7%~16.8%和3.2%~30.5%,但对莴笋茎该两个品质指标略有提高;莴笋叶硝酸盐含量增加8.0%~8.2%和11.4%~17.2%,莴笋茎硝酸盐含量在试验点1降低2.5%~11.5%,而试验点2则增加8.0%~13.5%。试验点1莴笋叶钙、镁、铁和锰含量为提高,试验点2降低。两个试验点秸秆钾替代化肥钾均显著提高莴笋对氮、磷和钾吸收量,以MH+KL处理莴笋钾素利用率最高。综合莴笋产量、品质、养分吸收和钾素利用效率,以MH+KL处理效果最佳。     

Effects of fractions of coal-derived humic substances on seed germination and growth of seedlings (Lactuga sativa and Lycopersicum esculentum)

Summary Lettuce and tomato seeds were treated in Petri dishes with a humic acid derived from an oxidized coal and with fractions of the same humic acid obtained by ultrafiltration through membranes of known molecular cutoff and by extracting with buffers set at pH 4 and pH 5. The unfractionated humic acid was applied at 40, 100, 1000, and 5000 mg l^-1 whereas the humic fractions were applied at 40, 100, and 200 mg l^-1. Germination parameters such as the number of total germinated seeds, the velocity of seed germination, the fresh weight and dry weight of total seedlings were measured and related to the chemical and physicochemical properties of the humic material. No increase in the germination percentage or the germination rate was observed for either lettuce or tomato seeds. The fresh weight of total seedlings and per seedling increased in treatments with unfractionated humic acid with increasing concentrations for both lettuce and tomato plants without showing signs of growth inhibition up to 5000 mg l^-1. This was attributed to cell elongation and more efficient water uptake. For the lettuce, the fresh weight both of total seedlings and per seedling was enhanced by treating the seeds with fractions of low molecular weight and high content of acidic functions, whereas the dry weight both of total seedlings and per seedling did not change with the humic fraction used. For the tomato seeds in contrast, the dry weight both of total seedlings and per seedling was increased by the use of unfractionated humic acid and by some of the humic fractions. An uptake of humic material by growing tomato seedlings was inferred.     

Influence of Dairy Cattle Slurry Solid Fraction Compost Combined with Mineral Nitrogen Fertilizer on the Growth of Greenhouse Lettuce

Winter lettuce response to the application of composts from the solid fraction of dairy cattle slurry was assessed in combination with mineral nitrogen (N) fertilizer throughout a randomized block experiment under greenhouse conditions. Lettuce yield did not increase with mineral N fertilizer, possibly because the lettuce was preceded by a heavily fertilized tomato crop, and the amount of mineral N (114 kg ha^?1) in the soil at the beginning of the experience was greater than the amount of N (64–89 kg ha^?1) accumulated in the lettuce shoots of all of the treatments. In contrast, lettuce yield and N uptake increased with compost application, suggesting other benefits in addition to N availability resulting from its use as a soil amendment. Therefore, dairy cattle slurry solid fraction mature compost can be recommended for vegetable production, and mineral N recommendation is suggested to pursue previous soil mineral N analysis.     

Effects of selenium supplementation on four agricultural crops

Agricultural crops can be used either to remediate selenium-contaminated soils or to increase the daily selenium intake of consumers after soil supplementation using inorganic or organic selenium sources. In this study, four agricultural crops were examined for potential selenium enhancement. Soils containing tomato, strawberry, radish, and lettuce plants were supplemented with either an inorganic or an organic form of selenium. Two different soils, i.e., low Se and high Se containing, were also used. Statistically significant differences in appearance, fruit production, and fresh weights of the fruit produced were studied. Next, the amount of selenium retained in the edible fruits, nonedible plant, and soil for each was analyzed by acid digestion followed by hydride generation atomic absorption analysis. Finally, inhibition effects on the seeds of the agricultural plants were studied. The results show that supplementation with an inorganic form of selenium led to higher retention in the plants, with a maximum of 97.5% retained in the edible portion of lettuce plants.     

响应面设计法在温室番茄栽培中的应用

为优化温室番茄的栽培条件,试验研究了不同栽培密度、施氮量和施钾量对日光温室番茄产量的影响。通过中心复合试验设计,构建三因素（栽培密度,氮肥,钾肥）五水平的响应面设计方法并建立番茄产量与三因子的二次回归数学模型。结果表明:三因素对温室番茄产量均有显著的影响（p0.01）,影响的大小顺序为栽培密度施钾量施氮量;栽培密度与施氮量、施钾量之间存在显著的交互作用（p0.01）,施氮量与施钾量之间的相互作用对番茄产量影响不显著（p0.05）;多元二次回归分析结果显示,栽培密度、施氮量、施钾量与番茄产量之间的回归模型高度显著（p0.01）。统计分析确定温室番茄的最佳栽培条件为:栽培密度4.83万株/hm2,施氮量262 kg/hm2,施钾量513kg/hm2;在此条件下,温室番茄产量的预测值为119381kg/hm2,验证试验所得产量为121005kg/hm2。本研究为日光温室番茄高产、稳产和优质提供了理论依据。     

Relationship between Selenium and Sulfur Assimilation and Resultant Interaction on Quality Parameters in Onion

The relationship between selenium (Se) and sulfur (S) uptake and their interaction on the pungency and quercetin contents of onion was investigated in a sand culture trial under polyhouse conditions. The results indicated that application of Se with increasing rates produced an antagonistic effect on S assimilation. An amount of 20 kg Se ha^–1 drastically reduced the S content in onion bulbs. Further, the pungency and quercetin concentration also declined. Foliar application of Se at 1.0 ppm resulted in production of bulbs with lower levels of pungency and quercetin. Though Se is essential from a health point, its application up to 10 kg ha^–1 was sufficient for enriching onions without much effect on the other essential bulb quality parameters.     

Uptake and distribution of selenium in tomato plants as affected by genotype and sulphate supply

Aim of this work was to investigate if the variation among tomato genotypes in selenium (Se) uptake and accumulation observed in short term experiments are maintained over longer growth periods and if there is a positive correlation in shoot between sulphur (S) accumulation and Se accumulation across different genotypes or if higher tissue S results in greater feedback inhibition of Se uptake. Two experiments were carried out under greenhouse conditions and different genotypes of Lycopersicon lycopersicum (UC82B and LA2711), Lycopersicon pennellii (LA716) and Lycopersicon peruvianum (LA2157) were grown until fruit ripening. The results obtained in the two experiments confirmed that sulphate in the growth solution reduced selenate uptake by plants and increased the S content of the leaves. Under low sulphate treatment there was a clear correlation (R²=0.82) between leaf S content and shoot Se content across genotypes in both experiments, indicating that the overall activity of the S transport systems also determines Se transport. Selenium was translocated from shoot to fruit, but the edible portion of the plant contained much less total Se than the inedible plant parts. The difference in Se content between the low and the high sulphate treatments was significantly higher in shoot than in root, confirming that the Se translocation from root to shoot is probably more affected by high sulphate supply than Se uptake by root. In the first experiment the genotype LA716 showed ah higher Se, accumulation together with higher S content in leaves, indicating a marked ability of this genotype to absorb ions from substrate. In the second experiment UC82B appeared to be more capable to accumulate Se and S rather than LA2711 and LA2157. In both experiments Lycopersicon peruvianum appeared to be less affected by the high concentration of ions in the growth solution and to be able to reduce ion uptake than Lycopersicon lycopersicum and Lycopersicon pennellii.