提高红掌叶片愈伤组织诱导和植株分化及壮苗率的技术研究     

夏时云  麦瑜玲  许继勇  郑添群  林书瀚  黄伟雄 《勤云标准版测试》2005,(2)

研究了不同培养基、糖类、培养条件及活性炭对红掌幼嫩叶片愈伤组织诱导和植株分化及壮苗率的影响。结果表明:在改良MS 6-BA1.0mg/l 2,4-D0.1mg/l,添加葡萄糖30g/l和暗培养,可获得较高的愈伤组织诱导率;在继代培养中添加活性炭1.0g/l,有利于提高幼芽分化和壮苗率。各个品种间的愈伤组织诱导率与植株分化率有一定差别。红掌组培苗无需另行作生根培养即可获得较为健壮的小苗,移栽成活率可达95%以上。试验  相似文献   

Rural income generation through improving crop-based pig production systems in Vietnam: Diagnostics,interventions, and dissemination   总被引：1，自引：0，他引：1  

Dai?PetersEmail author  Nguyen?Thi?Tinh  Mai?Thach?Hoan  Nguyen?The?Yen  Pham?Ngoc?Thach  Keith?Fuglie 《Agriculture and Human Values》2005,22(1):73-85

Sweetpotato-pig production is an important system that generates income, utilizes unmarketable crops, and provides manure for soil fertility maintenance. This system is widely practiced from Asia to Africa, with many local variations. Within this system, pigs are generally fed a low nutrient-dense diet, yielding low growth rates and low economic efficiency. Our project in Vietnam went through a process of situation analysis, participatory technology development (PTD), and scaling up over a seven-year period to improve sweetpotato-pig production and to disseminate developed technologies. The situation analysis included a series of pig production assessments in several provinces in northern and southern Vietnam, and pig supply-market chain identification was conducted in 13 provinces. The analysis of these studies informed the project of the following: (1) appropriate locations for our activities; (2) seasonal available feedstuff and farmers feeding practices; (3) market fluctuation and requirements; and (4) feeding and management improvement needs based on which the subsequent phase of PTD was designed. The PTD involved a limited number of farmers participating in sweetpotato varietal selection, sweetpotato root and vine silage processing, seasonal feeding combination, and pig feeding with balanced crop-feed diet and silage. Six years of multi-location and multi-season sweetpotato selection resulted in a few promising varieties that yielded up to 75% more dry matter and have since been formally released. The most significant results of silage processing and feeding trials include improved growth, higher feeding efficiency, increased year-round local feedstuff, and considerable labor reduction from eliminated cooking and vine cutting. Once these technologies were developed, a farmer-to-farmer training model was designed for scaling up the adoption and impact. Farmer trainers from seven communes in seven provinces received training in these technologies. In turn, they undertook the responsibility of training other farmers on sweetpotato selection, processing, and feeding. An impact study was also administered to monitor and evaluate (M&E) the dissemination process and to document the impact of the new technologies and farmer-to-farmer training model on pig growth and farmer income generation. The results showed that both participating and non-participating farmers have taken up the technologies, although the former demonstrates higher rates of adoption than the latter. The participants also generated more income and saved more labor from the adoption of the technologies. While the scaling up and M&E activities are on-going, the project has since broadened from a sweetpotato-pig system perspective to a pig-cropfeed system perspective based on farmers needs. It has included other crop feeds such as cassava and peanut stems in the research portfolio. New technologies based on on-going PTD will continuously be incorporated into the future training curriculum.Dai Peters is currently a senior scientist with the International Center for Tropical Agriculture (CIAT) based in Hanoi, Vietnam. This publication is based on research conducted while she was a research scientist with the International Potato Center (CIP). She holds a PhD from North Carolina State University. Her research interests include on-farm participatory research methodologies, agroenterprise development, and sweetpotato-pig farming systems in Vietnam and Papua, Indonesia. Her recent publications include a manual on crop-based pig feed systems, post-harvest fermentation of sweetpotato roots and vines, and agroenterprise development.Nguyen Thi Tinh is currently a coordinator of the sweetpotato-pig improvement project at the International Potato Center in Vietnam. Ms. Tinh holds a Masters degree in animal nutrition from Wageningen University, Netherlands. She participated in the project on pig feeding trials for five years.Mai Thach Hoanh is a sweetpotato breeder with the Root Crop Research Center of Vietnam Agricultural Science Institute (VASI). He holds a PhD in sweetpotato breeding from the same institute. He participated in the project for seven years on sweetpotato selection. Nguyen The Yen is a crop scientist in the Food Crop Research Institute of Vietnam. He holds a PhD in sweetpotato breeding from VASI. He participated in the project for five years on sweetpotato selection.Pham Ngoc Thach is a lecturer with the Hanoi Agricultural University. He holds a PhD in veterinarian science from the same university. He participated in the project for five years in controlling pig diseases during the feeding trials.Keith Fuglie is a regional coordinator and research scientist in the International Potato Center based at Bogor, Indonesia. He holds a PhD in agriculture economics from the University of Wisconsin. He designed the impact study for the project.  相似文献   

DNA: a programmable force sensor     

Albrecht C  Blank K  Lalic-Mülthaler M  Hirler S  Mai T  Gilbert I  Schiffmann S  Bayer T  Clausen-Schaumann H  Gaub HE 《Science (New York, N.Y.)》2003,301(5631):367-370

Direct quantification of biomolecular interaction by single-molecule force spectroscopy has evolved into a powerful tool for materials and life sciences. We introduce an approach in which the unbinding forces required to break intermolecular bonds are measured in a differential format by comparison with a known reference bond (here, a short DNA duplex). In addition to a marked increase in sensitivity and force resolution, which enabled us to resolve single-base pair mismatches, this concept allows for highly specific parallel assays. This option was exploited to overcome cross-reactions of antibodies in a protein biochip application.  相似文献   

Conversion of zinc oxide nanobelts into superlattice-structured nanohelices     

Gao PX  Ding Y  Mai W  Hughes WL  Lao C  Wang ZL 《Science (New York, N.Y.)》2005,309(5741):1700-1704

A previously unknown rigid helical structure of zinc oxide consisting of a superlattice-structured nanobelt was formed spontaneously in a vapor-solid growth process. Starting from a single-crystal stiff nanoribbon dominated by the c-plane polar surfaces, an abrupt structural transformation into the superlattice-structured nanobelt led to the formation of a uniform nanohelix due to a rigid lattice rotation or twisting. The nanohelix was made of two types of alternating and periodically distributed long crystal stripes, which were oriented with their c axes perpendicular to each other. The nanohelix terminated by transforming into a single-crystal nanobelt dominated by nonpolar (0110) surfaces. The nanohelix could be manipulated, and its elastic properties were measured, which suggests possible uses in electromechanically coupled sensors, transducers, and resonators.  相似文献   

大工业应用是解决秸秆问题的根本途径   总被引：5，自引：0，他引：5  

孙明湖  咸惠军  南方 《中国生态农业学报》2005,13(3):196-198

阐述了我国农作物秸秆利用现状及存在的主要问题,指出大工业应用是解决秸秆问题的根本途径,并提出具体对策。  相似文献   

Effects of fresh and aged copper contaminations on soil microorganisms     

Berndt‐Michael Wilke  Maike Mai  Andreas Gattinger  Michael Schloter  Ping Gong 《植物养料与土壤学杂志》2005,168(5):668-675

The aim of the investigation was to compare effects of fresh and aged amendments of copper (Cu) on the active, aerobic, heterotrophic microbial biomass by respiration and potential‐nitrification measurements and on microbial‐community structure by means of phospholipid‐fatty‐acid (PLFA) analyses. An A_p horizon (10–20 cm) of a Luvisol was used for the experiments. Fresh copper amendments were carried out by spraying a CuCl₂ solution on the soil. Aged heavy‐metal amendments were achieved by mixing the control soil with monocontaminated soil derived from an abandoned site in Denmark which has been used as a wood‐preservation plant. As expected, fresh contaminations were more effective to reduce potential nitrification and respiration than aged contaminations if the total Cu concentration (Cu_t) in soils is considered. There were no differences between aged and fresh contaminations if their effects were referred to NH₄Cl‐extractable concentrations (Cu_AN). The lowest concentration reducing cumulative substrate‐induced respiration (C_R) amounted to 0.33 mg Cu_AN (kg dm)^–1. PLFA analyses revealed Cu contaminations to decrease mainly aerobic bacteria. Effects were more pronounced using the contaminated soil as an inoculum. Apparently the duration of contamination is more important to the change of microbial‐community structure than the actual availability of the contaminant.  相似文献   

Serial abdominal radiographs do not significantly increase accuracy of diagnosis of gastrointestinal mechanical obstruction due to occult foreign bodies in dogs and cats     

Emily B. Elser  Wilfried Mai  Jennifer A. Reetz  Vince Thawley  Hadley Bagshaw  Jantra N. Suran 《Veterinary radiology & ultrasound》2020,61(4):399-408

Abdominal radiographs are commonly used in dogs and cats that present with gastrointestinal signs. When initial abdominal radiographs are equivocal for the presence or absence of gastrointestinal mechanical obstruction, follow‐up abdominal radiographs may be recommended. Based on our review of the literature, no published study has been performed to evaluate the clinical utility of serial abdominal radiographs in such cases. The purpose of this study is to determine whether follow‐up abdominal radiographs increase diagnostic accuracy for mechanical obstruction. A prospective cohort study was performed on client‐owned dogs and cats with clinical concern for gastrointestinal mechanical obstruction and initial abdominal radiographs inconclusive for the presence of obstruction. Follow‐up abdominal radiographs were performed between 7 and 28 h of the initial radiographs; an abdominal ultrasound performed within 3 h of the follow‐up study served as the gold standard. A total of 57 patients (40 dogs and 17 cats) were recruited; 19 of 57 cases (11 dogs; 8 cats) were mechanically obstructed, all with nonradiopaque foreign bodies. Four blinded reviewers (2 radiologists, 1 radiology resident, 1 criticalist) separately assessed the initial and the combined initial/follow‐up radiographic studies for diagnosis of mechanical obstruction; for each observer, there was no significant change in accuracy (P = .058‐.87) for the diagnosis of mechanical obstruction. Given the lack of significant increase in diagnostic accuracy using follow‐up radiographs in cases of occult gastrointestinal mechanical obstruction, other diagnostic options (eg, abdominal ultrasonography) could be considered when survey abdominal radiographs are inconclusive for the diagnosis of mechanical obstruction in dogs and cats.  相似文献   

Effect of Dietary Phosphorus Levels on Growth, Body Composition, Muscle and Bone Mineral Concentrations for Orange-Spotted Grouper Epinephelus coioides Reared in Floating Cages   总被引：1，自引：0，他引：1  

Qi C.  Zhou  Yong J.  Liu  Kang S.  Mai  Li X.  Tian 《Journal of the World Aquaculture Society》2004,35(4):427-435

A feeding experiment was conducted in floating cages (1.5 ± 1.0 ± 2.0 m) to determine the requirement of dietary phosphorus by juvenile orange-spotted grouper Epinephelus coicodes . Five isonitrogenous (approximately 54% CP) fishmeal-casein-based diets that contained 0.68, 0.77, 0.86, 1.02 and 1.21% total phosphorus from ingredients and supplemental monocalcium phosphate (MCP: 0, 0.75,1.51,2.26,3.02%) were fed to the fish previously fed a basal diet (0.68% total phosphorus) for 2 wk. Fish were fed in triplicate cages with one of the diets twice daily to satiation. After 8 wk of feeding, survival ranged from 70.0% to 81.7% with no significant difference among dietary treatments. The relative weight gain, specific growth rate, muscle lipid, ash, calcium, iron, zinc and phosphorus, bone ash, phosphorus, iron, and zinc were significantly affected by dietary phosphorus level. There were no significant effects of increasing total dietary phosphorus on hepatosomatic index, viscerasomatic index, condition factor, muscle moisture and protein, muscle magnesium, and manganese; and bone calcium, magnesium and manganese. Based on relative weight gain, specific growth rate and bone phosphorus, a dietary level of 0.86% total phosphorus is recommended for juvenile grouper growing in floating cages.  相似文献   

Dietary lysine level affects digestive enzyme,amino acid transport and hepatic intermediary metabolism in turbot (Scophthalmus maximus)     

Huang  Xinrui  Song  Xinxin  Wang  Xuan  Zhou  Huihui  Liu  Chengdong  Mai  Kangsen  He  Gen 《Fish physiology and biochemistry》2022,48(4):1091-1103

Fish Physiology and Biochemistry - Lysine is one of the most important essential amino acids in fish, especially in the feed formulated with high levels of plant ingredients. Lysine restriction...  相似文献   

Effects of dietary vitamin C on survival, growth, and immunity of large yellow croaker, Pseudosciaena crocea     

Qinghui Ai  Kangsen Mai  Beiping Tan  Wei Xu  Wenbing Zhang  Hongming Ma  Zhiguo Liufu 《Aquaculture (Amsterdam, Netherlands)》2006,261(1):327-336

An 8 weeks growth experiment was conducted to determine the effects of dietary vitamin C on the survival, growth, tissue ascorbic acid contents and immunity of large yellow croaker (Pseudosciaena crocea) with initial weight of 17.82 ± 0.68 g. Seven practical diets were formulated to contain 0.1, 12.2, 23.8, 47.6, 89.7, 188.5 and 489.0 mg ascorbic acid equivalent kg^− 1 diet, supplied as l-ascorbyl-2-polyphosphate (LAPP). Each diet was fed to triplicate groups of fish in seawater floating cages (1.5 × 1.5 × 2.0 m), and each cage was stocked with 120 fish. Fish were fed twice daily (05:00 and 17:00) to apparent satiation for 8 weeks. The water temperature fluctuated from 19.5 to 25.5 °C, the salinity from 25 to 28‰ and dissolved oxygen content was approximately 7 mg l^− 1 during the experimental period. Results showed that the specific growth rate (SGR) (from 1.80 to 1.96% d^− 1) had an increasing trend with the increase of dietary vitamin C, but no significant difference was observed among dietary treatments. No gross deficiency signs were observed in any of the experimental fish. Survival rate, however, significantly increased with increasing dietary vitamin C (P < 0.05). The vitamin C contents in liver and muscle correlated positively with the vitamin C in diets. The vitamin C requirement was estimated to be 28.2 mg kg^− 1 based on survival, and 87.0 mg kg^− 1 on liver content of vitamin C. The activities of serum lysozyme and alternative complement pathway (ACP), phagocytosis percentage (PP) and respiratory burst activity of head kidney significantly increased with increasing dietary vitamin C. The challenge experiment with Vibrio harveyi showed that fish fed the diets with supplementation of vitamin C had significantly lower cumulative mortality compared to the control group (66.7%), and the cumulative mortality (16.7%) in fish with 489.0 mg kg^− 1 ascorbic acid was significantly lower than that (41.7%) in fish with 23.8 mg kg^− 1 ascorbic acid. These results suggested that vitamin C significantly influenced the immune response and disease resistance of large yellow croaker.  相似文献