旱地长期定位施肥土壤剖面中有效硫累积及其影响因素

对设在黄土高原旱地黑垆土上不同N、P配比与用量的长期定位试验土壤剖面有效硫的分布与累积进行了研究。结果表明 ,长期施用不同量及不同配比的尿素与过磷酸钙肥料 ,对土壤剖面有效硫的含量影响明显 ,无硫投入的处理CK、N2、N4剖面有效硫含量低 ,平均分别为 7.73、10 .6 4、12 .16mg/kg ,分布均匀 ,而有硫投入的处理有效硫在剖面形成累积峰 ,最大含量可达 95.42mg/kg。大量的硫素随过磷酸钙施入土壤之后 ,部分以可溶无机硫酸盐形式被下渗水淋溶到土体的深层累积 ,累积量随施硫量的增加而增加 ,由于投入硫量大 ,在同一硫水平上 ,产量随氮肥用量增加而增加 ,但累积硫的量减少不多。石灰性土壤有效硫的下淋累积受作物、土壤、施肥、降水等多种因素影响 ,是长期的累积过程     

水稻和油菜施硫的增产效应及土壤有效硫临界指标的研究

硫是影响作物产量和农产品品质的重要元素之一[1-4] . 随着作物产量和复种指数的提高,不含硫的高浓度复合肥料用量的增加以及有机肥用量的减少,作物缺硫问题日趋严重.我国南方的许多省份施用硫肥均有不同程度的效果[5-11] .     

长江三角洲地区不同种植年限保护菜地土壤质量初探

保护地蔬菜栽培中氮肥的大量施用引起土壤氮素累积现象非常严重[1-3 ],并出现盐分累积和次生盐渍化的发生[4-5 ];而且保护地蔬菜栽培多年后还造成土壤pH降低,施肥量越大,pH降低幅度越大[6].伴随着土壤理化性状变化,保护地土壤微生物区系也发生了明显的变化,细菌数量显著下降,真菌数量增加,微生物活性降低[7-8].     

不同施铜水平下接种AM真菌对海州香薷根际pH的影响

研究表明,丛枝菌根(Arbuscular mycorrhiza,AM)真菌对宿主植物生长和吸收、转运重金属的作用受土壤pH的影响[1-3]。植物可以通过分泌质子或有机酸等改变根际土壤的pH,接种AM真菌可以改变宿主植物的根系分泌物[4-6],从而影响土壤pH。Li等[7]研究发现,接种AM真菌的白三叶在根-土界面、菌丝室及菌丝-土壤界面的pH均降低。Li和Christie[8]发现Zn污染土壤中接种G.mosseae降低了红三叶植物体内Zn浓度和吸收量;菌根处理土壤的pH比对照土壤高,土壤溶液中的Zn浓度低,在施Zn量大时尤为显著。AM真菌菌丝往往在利用NO3-N的同时释放出OH-,导致…     

傅立叶变换红外光谱法表征玉米秆茬培肥土壤胡敏酸的变化

土壤腐殖质是土壤肥力的重要物质基础,在土壤有机碳库中占有相当大的比重,腐殖质可分成三个组分:胡敏酸(HA,不溶于酸),富里酸(FA,溶于酸)[1]和胡敏素(HM)。其中胡敏酸是土壤腐殖质中的活跃成分,其存在形态、分子组成、理化性质的变化对土壤的肥力特征都会产生巨大影响[2-3]。玉米植株残体作为有机肥的一个重要组成部分,施入土壤后必然对土壤HA的数量、组成、结构及存在形式产生影响,并使其理化性质发生改变,从而起到改善土壤环境和培肥土壤的作用。研究证明,玉米植株残体施入土壤后,土壤胡敏酸的理化性质得到显著的改善[4-5]。张晋京等…     

硼对甘蓝型油菜不同品种苗期生理特性的影响

油菜是我国的主要油料作物之一,种植面积和总产量均居世界首位.油菜也是需硼较多的作物,我国几乎所有油菜主要产区都存在不同程度的土壤有效硼不足现象,严重影响油菜生产[1].80年代中期在推广单低、双低油菜品种时发现优质油菜品种比普通油菜对缺硼反应更敏感,随后我国不少地方开展了油菜缺硼基因型差异的研究[2～4]     

控释肥硫膜对酸性棕壤淋溶特性的影响

为预测硫包膜控释肥施用后大量硫膜残留对土壤生态系统造成的危害，设置硫膜材料添加量不同的室内淋溶试验，以研究控释肥硫膜材料对土壤淋溶特性的影响。研究结果表明；成分和量等同于硫膜的粉状硫磺可显著改变酸性棕壤淋溶液的pH和EC值及K^＋、Na^＋、Ca^2＋、Mg^2＋、SO42-的浓度，5次淋溶累计淋失的K^＋、Na^＋、Ca^2＋、Mg^2＋、SO4^2-随粉状硫磺加入量的增加而增加。而硫包膜尿素处理除对土壤SO4^2-、K^＋淋溶影响不明显外，对其他指标的影响较明显。试验同时发现，由于硫膜和粉状硫磺的物理形态不同，短期内对土壤淋溶特性的影响也有较大差异，但粉状硫磺的表现可以反映硫膜积累并转化后对土壤的影响。     

不同小麦品种(品系)耐缺锰能力的比较研究

在四川平原水旱轮作的缺锰土壤上,采用田间和盆栽试验相结合的方法研究了15个不同小麦品种（品系）的耐缺锰能力。结果表明,不同小麦品种的耐缺锰能力存在很大差异。多数小麦品种对缺锰敏感,少数品种具有较强的耐性。其中,小麦品系80-8既具有较强的耐缺锰能力,也是供试小麦品种中产量最高的,在缺锰土壤上具有很好的推广应用价值。通过盆栽试验可对不同小麦品种进行初步筛选。在缺锰条件下,不同小麦品种间地上部锰浓度没有显著差异,不宜作为判别小麦耐缺锰能力的指标。缺锰可见症状与缺锰耐性有较好的一致性,可作为初步筛选指标。田间试验相对产量是最可靠的鉴定指标。根系发达,根冠比较高是小麦耐缺锰的一个重要因素。     

土壤氮、磷营养过剩对微量元素锌、锰、铁、铜有效性及植株中含量的影响

土壤过量施用肥料,使部分菜地特别是保护地土壤中氮、磷养分积累过剩,导致蔬菜品质变劣,肥效下降,病虫害增多[1-2]。上世纪80年代日本已报道菜地过剩营养的不利影响,发现在土壤磷过高时,微量元素锰和铁出现异常[3]。据统计,京郊菜地土壤氮、磷养分已有明显积累,全市平均保护地土壤有效磷(P)含量达97·1mg/kg,个别区县高达165·8 mg/kg;土壤NO3-N含量平均为88·8 mg/kg,个别区县高达168 mg/kg[4]。在这种高氮、磷含量的土壤中,其它养分的变化也有必要进行研究。相对于大量元素,菜地土壤微量元素的研究较少[5],而且一般都是在常规施肥量的条…     

新疆玛纳斯河流域土壤盐分特征研究

以新疆玛纳斯河流域为研究区,结合面域土壤性状调研,利用相关分析和主成分分析方法对区域土壤盐分特征进行研究.结果表明,研究区域土壤盐渍化类型以硫酸盐为主,剖面土壤盐分含量呈现底聚分布特征;土壤盐分含量与SO42-、Ca2+离子含量呈极显著正相关;各层土壤盐分阴离子以SO42-为主,阳离子以Ca2+为主;SO42-、Ca2+、Mg2+及土壤盐分含量(St)是表征玛纳斯河流域土壤盐渍化的主要特征因子.本研究将为新疆玛纳斯河流域土壤资源可持续利用提供重要的理论依据.     

Role of selenium in mitigation of cadmium toxicity in pepper grown in hydroponic condition

Selenium (Se) is an essential element for humans but is not considered as essential for plants. However, its beneficial role in improving plant growth and stress tolerances is well established. In order to study the role of Se in cadmium (Cd) toxicity in pepper (Capsicum frutescens cv. Suryankhi Cluster), this experiment was carried out in greenhouse conditions. Treatments comprised Cd [0, 0.25, and 0.5 mM cadmium chloride (CdCl₂)] and Se [0, 3, and 7 µM sodium selenite (Na₂SeO₃)] with three replications. The result showed that Cd decreased chlorophyll a, chlorophyll b, and carotenoids, whereas Se supplementation diminished Cd toxicity on photosynthetic pigment. Selenium at 7 µM significantly increased the leaf area in the plants grown at 0.25 mM Cd. The application of Se at 3 µM with 0.25 mM Cd and Se at 3 µM and Se at 7 µM with 0.5 mM Cd increased the activity of catalase (CAT). Selenium at 7 µM decreased the proline content of pepper leaves exposed to Cd at 0.5 mM (30%). Selenium significantly enhanced the antioxidant activity of leaves, which was diminished by Cd toxicity. In general, Se has a beneficial effect on plant growth and is an antioxidant enzyme of pepper cv. Suryankhi Cluster under Cd stress and non-stress conditions.     

Accumulation of copper in soils and leaves of tomato plants in greenhouses in Turkey

Copper (Cu)‐containing fertilizers, fungicides, and bactericides has been used extensively in the greenhouses in the Antalya province in recent decades with the use of such materials tending to increase year by year. The level of DTPA‐extractable Cu was determined in 210 soils (0–20 and 20–40 cm depth) and 105 leaf samples obtained from 105 tomato greenhouses. The DTPA‐extractable Cu contents of the soils taken from the 0–20 depth ranged between 0.76 and 88.03 mg kg^‐1 (mean 7.79 mg kg^‐1). The percentage of soils containing DTPA‐extractable Cu greater than the critical toxicity level (20 mg kg^‐1) was 8.1. The Cu content of tomato leaf samples ranged between 2.4 and 1,490 mg kg^‐1 (mean 166.5 mg kg^‐1). The Cu concentration in leaf samples was very high due to the intensive use of foliar applied Cu‐containing chemicals. As a consequence, 24.8% of the leaf tomato samples analyzed contained over 200 mg Cu kg^‐1, the maximum accepted tolerance level. Therefore, it may be necessary to reduce the use of Cu‐containing pesticides and fertilizers, or at least reduce the amount of Cu‐containing fertilizers being used in those greenhouses where Cu‐containing pesticides have been or are being used.     

红壤区不同肥力水稻土根际硝化作用特征

通过根际培养箱(三室)——速冻切片技术研究了红壤地区高、低两种肥力下水稻苗期根表、根际和土体土壤矿质态氮含量和硝化强度,以及水稻生长、氮素积累的差异。结果表明,肥力水平对水稻根表和根际土壤铵态氮(NH4+-N)含量无显著影响,但高肥力显著提高土体土壤NH4+-N含量,以及根表、根际和土体土壤硝态氮(NO3--N)含量及硝化强度。两种肥力水稻土硝化强度最大值均出现在距根表2 mm处,分别为0.20和0.31μmol kg-1 h-1。土体土壤硝化强度随距根表距离增加而降低,低肥力土壤在距根表10～40mm处时硝化强度接近本底值,而高肥力土壤在距根表20～40 mm处时接近本底值。与不种水稻的CK相比,种植水稻显著提高根际土壤硝化强度。高肥力能显著改善水稻生长,增加植株氮素积累量,尤其显著促进根系生长及通气组织发育。由于红壤稻田肥力水平的差异造成水稻根际硝化强度以及水稻吸收NO3-的差异,导致高肥条件下水稻显示出更强的生长势和氮素吸收利用能力。因此,合理提高红壤稻田肥力水平对改善红壤区水稻根际土壤硝化作用及水稻氮素营养具有重要意义。     

Occurrence of Sexual Hormones in Sediments of Mangrove in Brazil

The presence of sexual hormones (female estrogens) was assessed in sediments of a mangrove located in the urban region of southern Brazil. The estrogens are involved in human sexual reproduction. They act as the chemical messengers, and they are classified as natural and synthetic. The estrogens inputs in the environment are from treated and untreated sewage. The presence of estrogens in sewage is excretion from the female due to natural production and use of contraceptives (synthetic estrogens). With the indiscriminate release of sewage into the environment, estrogens can be found in rivers, lakes, and even in oceans. In this work, the presence of estrone (E1), 17-??-estradiol (E2), and 17-??-ethynilestradiol (EE2) in eight sedimentary stations in Itacorubi mangrove located on Santa Catarina Island, south Brazil, was investigated. Historically, the Itacorubi mangrove has been impacted by anthropogenic activities because the mangrove is inserted in the urban area of the Florianopolis. The estrogen EE2, used as contraceptive, had the highest concentration in mangrove sediment, 129.75?±?3.89 ng/g. E2 was also found, with its concentration ranging from 0.90?±?0.03 to 39.77?±?1.19 ng/g. Following the mechanism, under aerobic or anaerobic conditions, E2 will first be oxidized to E1, which is further oxidized to unknown metabolites and finally to CO₂ and water (mineralized). EE2 is oxidized to unknown metabolites and also finally mineralized. Theoretically, under anaerobic conditions, EE2 can be reduced to E1 even in environments such as mangrove which is essentially anaerobic.     

自由基在鸡肾病发生中的作用研究

肾病即急性肾小管坏死.鸡肾病在养鸡生产中极为常见,尤其近年来,鸡肾病的发生日益增多,由于其发生机制不清楚,临床治疗鸡肾病的依据不足,致使治疗效果不佳,为此,提出本研究以探讨鸡肾病的发生机制,为本病防治提供理论依据.     

Meta-analysis in the Selection of Groups in Varieties of Citrus

Brazil is the largest producer of oranges (Citrus sinensis) in the world. The nutrient management of tree orchards is designed from experiments with a limited number of varieties. This knowledge is transferred to other varieties by diagnosing tissue nutrient composition and tree demand. Compositional data analysis has been first applied to tissue analysis of agricultural crops using centered log ratios with compositional nutrient diagnosis (CND-clr). The isometric log ratio (ilr) transformation is a new approach based on binary nutrient ratios and the principle of orthogonality (CND-ilr). We analyzed eleven nutrients: nitrogen (N), sulfur (S), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), boron (B), copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) in leaf tissue samples across 108 commercial plots (thirty-one grow Valencia, twenty-two Hamlim, twenty Pera, and thirty-five Natal). Nutrients were partitioned between macro- and micronutrients as well as anionic and cationic species. The effect size of varieties over Valencia was quantified by the mean and standard deviation of ilr values across ilr coordinates. Specific varietal nutrient profiles and ilr norms were defined. The nutrient profile of orange varieties could be classified into homogeneous groups to take advantage of fertilizer trials conducted on varieties of the same group. The Aitchison distance and a perturbation vector could be instrumental for diagnostic purposes and nutrient management.     

Effect of iron-quercetin complex on reduction of nitrite in in vitro and in vivo systems

This study investigated whether reducing agents such as quercetin and iron(II) facilitate formation of nitric oxide (NO) gas from orally ingested nitrite in an vivo study. When 3 mg/kg Na (15)NO2 was orally administered to rats with or without iron(II) or quercetin, Hb (15)NO, which is indicative of systemic (15)NO, was detected in the blood, with the maximum blood concentration of Hb (15)NO at 15 min after nitrite or nitrite plus quercetin treatment, whereas after administration of nitrite plus iron(II) or nitrite plus iron(II) and quercetin, the time was shortened to 10 min. Interestingly, iron(II), quercetin, or iron(II) plus quercetin did not affect the total amount of Hb (15)NO generated from orally administered Na (15)NO2. However, the systemic nitrite concentration was significantly decreased in the presence of iron(II) or iron(II) plus quercetin. These results may indicate that iron(II) is critical to the generation of NO gas from nitrite, whereas quercetin contributed little under the in vivo experimental conditions.     

旱地果园水肥管理模式研究进展

分析了旱地果园水肥管理模式的研究进展和存在问题,指出水肥胁迫尤其是水钾已成为旱区果树高产稳产优质化的主要限制因子。在系统探讨旱地果园水分管理、养分管理、综合管理以及果树叶营养综合诊断施肥标准的基础上,提出了旱地果园的高效水肥管理模式。     

Role of aldehyde oxidase in the hepatic in vitro metabolism of 3-methylindole in pigs

The metabolism of 3-hydroxy-3-methylindolenine (HMI), a recently discovered metabolite of 3-methylindole (3MI, skatole) produced by porcine liver microsomes, was investigated in vitro using porcine liver cytosol. HMI was rapidly metabolized to a single product, 3-hydroxy-3-methyloxindole (HMOI), by porcine cytosol. By the use of the selective inhibitors menadione and quinacrine, it was shown that the enzyme responsible for the oxidation of HMI into HMOI was aldehyde oxidase (AO; aldehyde:oxygen oxidoreductase, EC 1.2.3.1). The activity of AO in the conversion of HMI to HMOI was measured in a population of pigs (n = 30) with a wide range of 3MI levels in back fat (0.07-0.30 mg/kg). AO activity was found to be negatively correlated (r = -0.70; P < 0.001) with the level of 3MI in fat. The results of the present study suggest that AO plays an important role in the metabolism of 3MI in the pig and that its catalytic activity is related to an adequate 3MI clearance.     

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。