闽北山区坡地农林复合经营生态模式的研究

研究了闽北山区坡地农林复合经营生态模式,优化配置了杉木－胡枝子－食用菌和杉木－百喜草－黄花菜２种具有较好生态经济效益的模式,分析了其生态与经济效益。     

杉木速丰林栽培技术探究

杉木是一种生长快、栽培广的经济树种,具有极高的经济价值和生态价值,而随着杉木种植范围的不断扩大,其在林业经济发展中也显得越来越重要。因此,相关部门与人员应加强对杉木速生林栽培技术的应用,从而不断提升杉木种植的质量与产量,以便更好地促进其经济效益的提高。基于此,就杉木速生丰产林栽培技术进行分析与探讨。     

桂西北田林老山中山杉木人工林生态研究报告

从生态学和生态经济学的角度,在全面调查和多年定位研究的基础上,以生物生产力和木材产量为指标,论述了桂西北田林老山中山杉木引种栽培区林分生长和产量与气候、土壤、微生物、地质地貌和经营措施之间的关系,并对林分的经济效益、生态效益和社会效益作了全面分析。结果表明:田林老山中山的自然生态条件完全满足杉木速生丰产的需要,现实林分生产力与杉木中心产区相当,并大大高于扩大栽培区,达到速生丰产林的标准。获得了显著的经济、生态和社会效益,可作为广西杉木商品性生产新基地。     

高峰林场杉木大径材全周期经营措施探索

杉木是我国特有速生丰产树种,主要生长于南方,以其较高的经济价值、药用价值及生态价值备受人们青睐。杉木广泛运用于桥梁、建筑、家具制作等领域,成为南方重要的商品材。广西凭借得天独厚的地理位置和气候特点,为杉木种植提供了良好的环境基础。近年来,广西加大杉木科研力度,提高种植技术,着力于杉木大径材的培育。杉木种植的经济效益、生态效益得到明显提升。基于此,围绕广西杉木种植现状,研究杉木大径材培育难点和重点,提出杉木大径材培育的改善措施。希望可以为林业种植技术研究提供借鉴。     

广西杉木病虫害防治对策

杉木在广西的分布较广,因其具有生长快、经济效益高等特点已成为了广西速丰林中的主要树种之一。随着杉木的种植的不断发展,病虫害的问题也日益突出,且危害的面积大,严重影响了杉木的生长质量,已经成为了制约杉木发展的重要问题,对于广西的经济建设也有着重要的影响。因此,做好杉木的病虫害防治工作,是保证杉木质量和经济效益的重要举措。基于此,调查广西杉木病虫害的危害现状、发生种类和特点,并详细探讨杉木常见的病虫害及其防治对策,以期为广西林业工作提供参考价值。     

不同龄组杉木生态公益林空间结构特征分析

杉木生态公益林不只是经营为目的的具有杉木林的森林或者林地,更重要的是具有保护环境、维持生态平衡、为科学提供试验地等不可忽视的作用。树林以及森林都是一个系统,其空间结构的特征决定着功能,同时生态公益林的空间结构更是有助于发挥树林的多样功能。杉木生态公益林的空间结构主要包含杉木在空间属性的排列方式及其分布的格局等,这些因素都会对杉木的稳定性以及经营发展方向起到决定性影响。杉木的经营策略可以分析生态公益林的空间结构,这是质量调控的前提和重要基础。基于此,从不同龄组的杉木生态公益林的空间结构特征进行分析,从概述、方法、目的等几个方面进行详细分析。     

桂西北地区杉木速生丰产技术应用与推广探究

杉木是植树造林中的主要经济树种,也是广西地区造林的主要使用树种。杉木有着木质优质、生长周期短、经济效益高等多个优点,因此也被广泛应用于各行各业之中,创造了极高的经济效益和社会效益。目前,杉木速生丰产造林技术已经被广泛应用于桂西北地区的林业造林工作中,为了进一步提升林业行业的效益,需要不断对杉木速生丰产技术进行优化、应用和推广。基于此,总结杉木的生长环境以及杉木速生丰产造林技术,探究该技术的推广应用措施。     

良种杉木造林技术要点及发展建议

杉木是我国南方地区广泛种植的经济树种,有着良好的经济效益和环境效益。但是在杉木造林中,不少林场都没有重视对造林技术的合理应用,存在着技术实施不规范的问题,影响了造林效果。基于此,从杉木的生长习性出发,就良种杉木造林技术要点进行分析,提出了杉木造林的合理化建议。     

杉木良种推广造林技术及应用探究

在经济的推动下,林业产业得到了快速发展,杉木良种推广造林技术的重要性日益凸显。杉木具有祛风止痛、散瘀止血等疗效,在我国各地均有广泛种植,为了有效发挥杉木的环境效益和经济效益,应重视杉木良种推广造林技术中资源的整合。基于此,对杉木良种推广造林技术的应用价值进行分析,对杉木良种推广造林技术的处理过程进行探讨,为杉木良种推广造林技术的应用提供依据。     

杉木造林技术及其经济效益分析

随着国家经济建设的快速发展,对各种木材的需求量越来越大,而杉木具有经济效益、生态效益及社会效益高等诸多优点。主要探讨杉木造林技术及其经济效益,以期对以后杉树的造林技术提供一定的参考。     

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.     

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.     

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。     

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.     

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.     

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.     

北京市郊典型农田施肥研究与分析

通过问卷调查形式,对京郊粮田、菜田和果园3种农田施肥现状进行研究.结果表明,菜田和果园化肥施用量较高,氮、磷、钾肥均显著高于粮田.菜田和果园氮肥用量分别为1741.0和1172.8 kg/hm2,分别是粮田氮肥用量的4.5和3.0倍;磷肥用量分别为1375.1和996.4 kg/hm2,分别是粮田磷肥用量的15.5倍和11.2倍;钾肥用量分别为791.3和602.4 kg/hm2,分别是粮田钾肥用量的21.1和16.1倍.另外,3种利用方式的农田氮、磷和钾肥施用比例不同,粮田为75.4%、17.3%和7.3%;果园为42.3%、36.0%和21.7%;而菜田为44.6%、35.2%和20.3%.3种种植类型中均存在氮肥投入过量、钾肥不足的问题.