Role of active aluminum in the formation of water-stable macroaggregates     

Saiyed Md. Ibrahim  Yoshiaki Inoue  Haruo Shindo 《Soil Science and Plant Nutrition》2013,59(4):685-689

Soil structure is determined by the arrangement of particles in soil and the particles of sand, silt, and clay bind together into aggregates of various sizes by organic and inorganic materials. Structural stability which is the ability of the aggregates and pores to remain intact when subjected to stress, markedly affects crop production and soil erosion (Tisdall 1996). Since water, either directly as rainfall or as surface runoff is the main agent of aggregate breakdown, in the analyzes of stable soil aggregation, the term water-stable aggregation is generally used (Lynch and Bragg 1985). Water-stable aggregates have been divided into micro aggregates < 0.25 mm dia.) and macro aggregates (> 0.25 mm dia.) (Edwards and Bremner 1967; Tisdall and Oades 1982). Microaggregates show a relatively high stability against physical disruption (Edwards and Bremner 1967). On the other hand, macro aggregates are sensitive to soil management (Tisdall and Oades 1982).

There are many reports on the relationships between the aggregate stability and the soil physicochemical properties. For example, significant correlations were found between the aggregate stability and the amounts of organic C (Tisdall and Oades 1982), total N, and carbohydrates or the CEC (Chaney and Swift 1984). However, most of these studies were conducted in non-volcanic ash soils. Volcanic ash soils are widely distributed in Japan and are very important soils for crop production. The objective of this study was, therefore, to obtain more information on the relationship between the degree of macro aggregation and the soil physicochemical properties in non-volcanic and volcanic ash soils.  相似文献   

Microbial distribution and function across wheat rhizosphere with oxamide and ammonium sulfate as N sources     

Md. Yunus Miah    Chih-Yu Chiu  Hiroaki Hayashi  Mitsuo Chino 《Soil Science and Plant Nutrition》2013,59(4):787-796

Analysis of the effect of slow-releasing N fertilizers on microbial parameters of the rhizosphere soil is essential for their effective use. This investigation revealed the comparative effects of oxamide and ammonium sulfate as different N sources on some selected microbial parameters as well as the pH in the rhizosphere of wheat (Triticum aestivum cv. Nourin No. 61). The study was conducted on a Japanese upland alluvial soil using a rhizobox system. In the central compartment (CC) of the rhizoboxes treated with oxamide and ammonium sulfate, four wheat seedlings were grown for 53 d. In either of the treatments, the pH of the rhizosphere soil increased with the increase in the distance from the CC. In contrast, nitrate production, bacterial and fungal numbers, microbial biomass nitrogen, and β-acetylglucosaminidase activity decreased with the increase in the distance, with the highest values of the respective parameters being recorded in the CC. However, remarkable changes of these microbial parameters were found within a distance of 1–2 mm from the CC to the distant compartments. Thus the results indicated that pH, bacterial number, and nitrate production were high in the oxamide treatment. In contrast, higher fungal number, microbial biomass N, and .B-acetylglucosaminidase activity were associated with the ammonium sulfate treatment. It was assumed that the significant (p<O.05) effect of the rhizosphere on microbial activities varied with the treatments.  相似文献   

Phytochemical screening, cytotoxicity and antibacterial activities of two Bangladeshi medicinal plants     

Roy A  Biswas SK  Chowdhury A  Shill MC  Raihan SZ  Muhit MA 《Pakistan journal of biological sciences: PJBS》2011,14(19):905-908

The objectives of the present study were to investigate phytochemical screening and to assay cytotoxicity and antibacterial activities of ethanolic extracts of leaves of two medicinal plants, Aglaonema hookerianum Schott (Family: Araceae) and Lannea grandis Engl. (Family: Anacardiaceae) available in Bangladesh. The brine shrimp lethality bioassay showed that the ethanolic extracts of Aglaonema hookerianum and Lannea grandis possessed cytotoxic activities with LC50 5.25 (microg mL(-1)) and 5.75 (microg mL(-1)) and LC90 10.47 (microg mL(-1)) and 9.55 (microg mL(-1)), respectively. Two extracts obtained from leaves were examined for their antibacterial activities against some gram positive bacteria such as Bacillus subtilis, Bacillus megaterium and Staphylococcus aureus, also gram negative strains of Pseudomonas aeruginosa, Escherichia coli, Shigella dysenteriae, Salmonella typhi, Salmonella paratyphi and Vibrio cholerae. Agar disc diffusion method was applied to observe the antibacterial efficacy of the extracts. Results indicated that both plant extracts (500 microg disc(-1)) displayed antibacterial activity against all of the tested microorganisms. These results were also compared with the zones of inhibition produced by commercially available standard antibiotic, Amoxicillin at concentration of 10 microg disc(-1). Observed antibacterial properties of the ethanolic extract of Aglaonema hookerianum Schott and Lannea grandis Engl. showed that both plants might be useful sources for the development of new potent antibacterial agents.  相似文献   

A potato breeding technique used for Texas     

Bruce A. Perry  Robert V. Akeley Md.  W. B. Cook 《American Journal of Potato Research》1960,37(9):306-307

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小麦衰老相关基因TaSAG39的生物信息学及表达模式分析     

孙丽丽  晋秀娟  赵锴  Md Ashraful Islam  卢娟  王曙光  孙黛珍 《华北农学报》2022,37(2):18-27

半胱氨酸蛋白酶是蛋白质降解过程中的一类水解酶,参与植物的衰老与成熟,在植物生长发育过程中发挥重要作用。基于前期得到的小麦衰老阶段转录组数据中筛选到一个衰老特异的半胱氨酸蛋白酶(SAG39),为了研究TaSAG39基因在小麦衰老过程中发挥的作用,采用生物信息学分析方法和实时荧光定量(qRT-PCR)技术对TaSAG39的基因结构和表达模式进行分析。结果表明,其氨基酸序列与小麦祖先种节节麦、野生二粒小麦以及硬粒小麦亲缘关系最近,含有木瓜蛋白酶亚家族特有的活性位点Cys-His-Asn以及EFNIN结构。TaSAG39-5A、TaSAG39-5B、TaSAG39-5D基因组全长分别为1 455,1 435,1 439 bp,编码序列长分别为1 041,1 050,1 038 bp,均含2个外显子和1个内含子;其编码的蛋白分别由346,349,345个氨基酸组成,分子质量约37 ku,等电点5.53～5.67,为稳定的带负电的亲水性蛋白;主要构成元件为无规则卷曲和α-螺旋,在蛋白质N段含有信号肽,具有保守的Inhibitor＿I29和Peptidase＿C1结构域,含有35～37个磷酸化位点,...  相似文献   

Effects of incubation times and moisture regimes on pH values and exchangeable cations in acid sulfate soils as influenced by application rates of basic slag     

Abul Hasnat Md. Shamim  Md. Harunor Rashid Khan  Takeo Akae 《Paddy and Water Environment》2009,7(2):95-103

Severe acidifications in acid sulfate soils (ASSs) have occurred worldwide due to sulfuric acidity, which requires sustainable measures for their reclamation. Accordingly, an incubation study was conducted with the topsoil of two different ASSs (Cheringa and Badarkhali) to evaluate the effects of basic slag (BS; size <1 mm, pH 9.6, Ca 20.8%, Mg 9.8%, etc.), on reduction of acidity and changes in exchangeable cations. It is noted that BS is a byproduct of steel industry in Bangladesh and can be collected almost free of charge. These soils received BS at the rate of 0 (T₀), 11 (T₁), 22 (T₂) and 33 (T₃) t ha⁻¹ under various moisture regimes (saturated condition M₁,_, i.e., 100% moisture content, wetting–drying cycles of 100 and 50% moisture M_2, and moisture at field condition M₃, i.e., 50%). The impacts of these treatments on some selected parameters in these soils were studied within 180 days of incubation. The application of BS was found to increase the pH of soils from 3.6 to 5.1 for Cheringa, 3.9 to 5.2 for Badarkhali soils at the end of incubation. These increments were more striking with the highest doses of BS under saturated moisture conditions in both of the soils. The ECe of the soils was not much influenced by the application of BS regardless of time. The treatments exerted significant (P ≤ 0.05) effects on exchangeable cations in different periods of incubation. The striking changes were recorded for the rate of increments of Ca²⁺ and Mg²⁺, which were about 2–3 times higher for Ca and more than 2 times higher for Mg²⁺ compared with the control after 180 days of incubation. These results suggest that the application of BS not only increased the Ca²⁺ to the higher amount than that of the increment of Mg²⁺ in the soils, but also improved one of the important criteria of Ca²⁺ and Mg²⁺ ratio in the soils.  相似文献   

State of Urban Nurseries in Bangladesh: A Case Study from the North-Eastern Region     

Romel Ahmed  Md. Sorif Hasan  Md. Abdul Halim  Mahbubul Alam 《Small-Scale Forestry》2008,7(3-4):275-283

The state of urban seedling nurseries in the north-eastern region of Bangladesh is examined with a focus on production and profitability of the enterprises. Twenty-eight sample nurseries out of the 97 nursery enterprises in Sylhet town were selected at random, and operators personally interviewed. It was found that the entrepreneurs are not highly educated though they believed that a basic level of education is required to understand the management of young nursery stock. Labourers of various employment categories work in the enterprises and their wage is determined by their skill, gender and efficiency. Capital and operating costs vary among the enterprises according to land value, production capacity, infrastructure type and workforce size. Production capacity ranges from 10,000 to 5 M seedlings/year with an average 836,000, though actual average production is only 341,000 seedlings/year. The production cost per seedling ranges from Tk. 4 to 50 while sale value ranges from Tk. 10 to 60. The most frequently sold species are Acacia mangium, Swietenia macrophylla, Tectona grandis, Mangifera indica, Litchi chinensis and Cocos nucifera. Nursery techniques and cultural practices adopted by nursery operators depend on the type of species and its silvicultural requirement. Despite some problems, including lack of suitable land for nursery establishment and inadequate level of technical knowledge for high quality seedling management, it seems that production of tree seedlings is a promising profitable small-scale business in the study area.  相似文献   

棕榈在孟加拉乡村传统利用——一种可持续的生物多样性管理手段(英文)     

Mohammad Shaheed Hossain Chowdhury  Md. Abdul Halim  Nur Muhammed  Farhana Haque  Masao Koike 《林业研究》2008,19(3)

采用多级采样的方法研究了孟加拉国农村耕作区内棕榈树的传统利用模式和当地的管理经验。农民管理棕榈主要为获取树液产品,生产以糖为主的次生品。树液可直接用作饮料,也可加工成糖蜜或酒精饮料。7块不同地块为棕榈提供生长环境,20.40%的棕榈种植在果园内。尽管中等级的农民拥有多数棕榈(33%),但是主要管理棕榈的是没有土地的农民,他们靠棕榈维持生计。这些农民将自己的智慧应用到棕榈管理当中,从种植到开孔取树液再到产品加工。如果能更科学地管理棕榈,加上农民的智慧,棕榈业将会对当地经济发展起到重要作用,也会丰富当地生物多样性。  相似文献   

Consumption of shark products: The interface of sustainability,trade (mis)labelling,human health and human rights     

Md Robiul Hasan  Jennifer A. Chaplin  Peter B. Spencer  Matias Braccini 《Fish and Fisheries》2023,24(5):777-795

Sharks and rays evolved 450 million years ago, during the Late Ordovician Period. However, during the modern Anthropocene, shark populations have declined at considerable rates, and recent global assessments indicate about one in three species is threatened with extinction. A notable reason for this elevated extinction risk is overfishing linked to increased demand for shark fins and other products. Here, we review multiple dimensions of consuming shark products, ranging from stock sustainability, product (mis)labelling and trade, the human health implications of consuming shark products, and illegal, unreported and unregulated fishing and slavery and labour abuses in the fishing industry. We conclude that traceability and increased transparency in seafood supply chains is essential to overcome obstacles to consumption of sustainable, ethical and healthy shark products. We also provide a decision tree outlining steps in consumer choice that would foster such consumption. Our aim is to provide a holistic view on issues concerning the consumption of shark products that will help policymakers, the public, management and law enforcement agencies to advocate for ecologically- and ethically sustainable consumption of shark products and thereby empower the general public to make informed decisions on which shark products they consume.  相似文献   

Optimizing nursery diets for post-metamorphic stage black sea bass: Growth performance,body composition,and feed utilization on open-formulated and commercial starter diets     

Md Shah Alam  Wade O. Watanabe  Patrick M. Carroll  Jennifer E. Gabel 《Journal of the World Aquaculture Society》2023,54(1):113-130

The objective of this study was to optimize nursery diets for post-metamorphic stage black sea bass by evaluating growth performance, whole-body proximate and fatty acid composition, and utilization of University of North Carolina Wilmington (UNCW)-formulated and commercial diets under laboratory conditions. A feeding trial was conducted to compare two UNCW-formulated diets (D1 and D2) for black sea bass (54% crude protein = CP and 14% crude lipid = CL) and two premium, commercial marine finfish fry diets, Otohime (Reed Mariculture Inc., Campbell, CA, CP = 48% and CL = 14%, CD3) and Gemma Diamond (Skretting, Nutreco, Canada, CP = 57%, CL = 15%, CD4). The UNCW-formulated diet 1 (D1) contained high fish meal (FM, 40% of diet), whereas UNCW-formulated diet 2 (D2) replaced 50% FM protein by high-quality poultry by-product meal (PBM) protein. Post-metamorphic stage black sea bass (~0.60 g, d40ph) were stocked in each of sixteen 75-L tanks at a density of 1 fish per L (75 per tank), with four replicate aquaria per treatment. Fish were fed four times per day (0800, 1100, 1400, and 1600 h) to apparent satiation for 30 days. Final body weight (5.70–5.74), specific growth rate (7.40–7.45%/d), and percent body weight gain (834–848%) of fish fed the UNCW-formulated D1 (FM-based) and D2 (FM + PBM-based) were higher (p < .05) than in fish fed the commercial diets CD3 and CD4 (4.66–5.21 g, 6.80–7.15%/d, and 668–756%, respectively). Feed intake (% body weight/d was significantly lower for fish fed commercial diet (CD4) (3.94) compared with fish fed CD3 (4.20), but feed intake for CD3 was not significantly different compared with the UNCW-formulated diets D1 and D2 (4.10–4.12). Feed conversion ratios (0.76–0.82) were significantly higher for fish fed CD3 (0.82) than for fish fed D1 and CD4 (0.76). Survival was high (99–100%) in all diet treatments. Final whole-body crude protein content (15.2 to 15.9% wet basis), moisture (68.9–69.6%), and ash (4.31–4.77%) showed no significant differences; however, whole-body crude lipid was lower in fish fed CD3 (9.67%) than in fish fed the other diets (9.96–10.22%). Final whole-body fatty acid composition reflected the diet composition. Higher feed consumption and growth of fish fed the UNCW-formulated diets were attributed to a more optimal combination of marine (fish, squid, and krill meals), terrestrial plant (soybean meal) protein sources, and the addition of chemo-attractants, which provided both higher nutritional quality and palatability. The study suggests that the species-specific starter diets may improve growth performance and fingerling quality and may therefore lower production costs under intensive nursery conditions.  相似文献