Current status and prospects of farming the giant river prawn Macrobrachium rosenbergii (De Man) in Bangladesh     

Md Abdul Wahab  Sk Ahmad‐Al‐Nahid  Nesar Ahmed  Mohammad M Haque  Mahmudul Karim 《Aquaculture Research》2012,43(7):970-983

Giant river prawn (Macrobrachium rosenbergii) farming plays an important role in the economy of Bangladesh. Presently, it is cultured in around 50 000 ha area with total annual production of 23 240 t. Traditional extensive prawn farming has been expanding over the last three decades through the introduction and adoption of improved culture systems, such as culture of prawn‐carps, prawn‐shrimp‐fish and prawn‐fish‐rice as concurrent and rotational systems. Efforts for the development of improved techniques on broodstock management, seed production and rearing and grow‐out of prawn have been made over the last decade. The outcomes are low‐cost feed for broodstock, production of post‐larvae in net cages (hapa), all‐male prawn culture, periphyton based prawn‐tilapia culture, C/N based prawn culture, organic prawn farming, prawn‐mola culture and prawn‐carp‐mola polyculture. Despite the development of culture technologies, a number of challenges for sustainable development of prawn farming need to be overcome to realize the potentials of this promising sector. Good aquaculture practises at all levels and application of measures for quality control and food safety would ensure sustainable development of prawn farming in Bangladesh.  相似文献   

Soil organic matter fractionation as a tool for predicting nitrogen mineralization in silty arable soils     

M. A. Kader  S. Sleutel  S. A. Begum  K. D’Haene  K. Jegajeevagan  S. De Neve 《Soil Use and Management》2010,26(4):494-507

After decades of searching for a practical method to estimate the N mineralization capacity of soil, there is still no consistent methodology. Indeed it is important to have practical methods to estimate soil nitrogen release for plant uptake and that should be appropriate, less time consuming, and cost effective for farmers. We fractionated soil organic matter (SOM) to assess different fractions of SOM as predictors for net N mineralization measured from repacked (disturbed) and intact (undisturbed) soil cores in 14 weeks of laboratory incubations. A soil set consisting of surface soil from 18 cereal and root‐cropped arable fields was physically fractionated into coarse and fine free particulate OM (coarse fPOM and fine fPOM), intra‐microaggregate particulate OM (iPOM) and silt and clay sized OM. The silt and clay sized OM was further chemically fractionated by oxidation with 6% NaOCl to isolate an oxidation‐resistant OM fraction, followed by extraction of mineral bound OM with 10% HF (HF‐res OM). Stepwise multiple linear regression yielded a significant relationship between the annual N mineralization (kg N/ha) from undisturbed soil and coarse fPOM N (kg N/ha), silt and clay N (kg N/ha) and its C:N ratio (R² = 0.80; P < 0.01). The relative annual N mineralization (% of soil N) from disturbed soils was related to coarse fPOM N, HF‐res OC (% of soil organic carbon) and its C:N ratio (R² = 0.83; P < 0.01). Physical fractions of SOM were thus found to be the most useful predictors for estimating the annual N mineralization rate of undisturbed soils. However, the bioavailability of physical fractions was changed due to the disturbance of soil. For disturbed soils, a presumed stable chemical SOM fraction was found to be a relevant predictor indicating that this fraction still contains bio‐available N. The latter prompted a revision in our reasoning behind selective oxidation and extraction as tools for characterizing soil organic N quality with respect to N availability. Nonetheless, the present study also underscores the potential of a combined physical and chemical fractionation procedure for isolating and quantifying N fractions which preferentially contribute to bulk soil N mineralization. The N content or C:N ratio of such fractions may be used to predict N mineralization in arable soils.  相似文献   

Effects of salinity on the growth and proximate composition of selected tropical marine periphytic diatoms and cyanobacteria     

Helena Khatoon  Sanjoy Banerjee  Fatimah Md Yusoff  Mohamed Shariff 《Aquaculture Research》2010,41(9):1348-1355

Marine periphytic cyanobacteria and diatoms have been examined as a potential source of feed supplement for rearing aquatic larvae in the aquaculture industry. Culture of the periphytic diatom Amphora sp., Navicula sp., Cymbella sp. and the cyanobacteria Oscillatoria sp. at different salinities showed significant changes in biomass and specific growth rates. Diatoms growth was significantly higher at 35 g L⁻¹, while for cyanobacteria growth was better at 25 g L⁻¹. Significantly higher levels of protein and lipid were found in diatoms at low salinities (15–25 g L⁻¹) and an increase in carbohydrate at high salinities (30–35 g L⁻¹). Conversely, cyanobacteria showed a significantly higher lipid content at 30–35 g L⁻¹ compared with other salinity levels but no significant changes were observed in the protein and carbohydrate contents at different salinity levels. The present findings can be taken into consideration when culturing marine periphytic Amphora sp., Navicula sp., Cymbella sp. and Oscillatoria sp. to provide appropriate levels of protein, lipid and carbohydrate as feed supplement as well as for bioremediation in aquaculture.  相似文献   

C. Clare Hinrichs and Thomas A. Lyson (eds.): Remaking the North American Food System: Strategies for Sustainability     

Molly D. Anderson 《Agriculture and Human Values》2009,26(3):251-252

  相似文献   

Pamela Walker: Growing good things to eat in Texas: Profiles of organic farmers and ranchers across the state     

Patrick T. Lillard 《Agriculture and Human Values》2010,27(4):527-528

  相似文献   

The significance of VA-Mycorrhiza to future arable farming in the Netherlands     

T. Limonard  M. A. Ruissen 《European journal of plant pathology / European Foundation for Plant Pathology》1989,95(1):129-135

Present conditions of high inputs and narrow rotations render the importance of vesicular-arbuscular mycorrhiza (VAM) in arable farming in the Netherlands rather low. Changes expected in the near future under the influence of economic pressures and environmental problems may change this situation. This is discussed in the light of some such expected changes in Dutch arable farming.  相似文献   

Toxicity and electrophysiological effects of Spilanthes amella Murr. extracts on Periplaneta americana L.     

Habsah A. Kadir  Muhamad B. Zakaria  Abdul A. Kechil  Moh D. S. Azirun 《Pest management science》1989,25(4):329-335

The potential insecticidal activity of Spilanthes acmella Murr. (Compositae) extracts was assessed in this study. The extracts were shown to be toxic against adults of American cockroach, Periplaneta americana L. The active component in S. acmella extract was isolated and identified as N-isobutyl-2,6,8-decatrienamide (spilanthol). The results from topical application of spilanthol show that it has a high acute toxicity and spilanthol was the most potent compound when compared to three conventional insecticides. The potency was found to be 1.3, 2.6 and 3.8 times more toxic than carbaryl, bioresmethrin and lindane, respectively. Electrophysiological studies indicated immediate hyperexcitation followed by complete inhibition of the cockroach cercal nerve activity.  相似文献   

Molecular breeding for virus resistant potato plants     

Marianne J. Huisman  Erik Jongedijk  Dinie Posthumus-Lutke Willink  Frank Van Der Wilk  Ben J. C. Cornelissen 《European journal of plant pathology / European Foundation for Plant Pathology》1992,98(2):29-36

To engineer resistance against potato virus X (PVX), the viral coat protein (CP) gene has been introduced into two potato cultivars. Stable expression of the gene in transgenic clones throughout the growing season has been obtained and resulted in considerably increased virus resistance. With varying frequencies depending on the original cultivar used, true-to-type PVX resistant transgenic clones have been obtained. Since deviant light sprout characteristics were invariably associated with aberrations in plant phenotype, they can be used in procedures to early screen for deviations. Furthermore, it has been possible to unequivocally discriminate between the original untransformed and independent transgenic cultivars. Although no relation has been found between the presence, if any, of the CP of potato virus Y (PVY) or potato leafroll virus (PLRV) in CP gene transgenic potato, appreciable levels of resistance to these viruses has been obtained. This suggests that the mechanism by which a viral CP gene in the potato genome evokes resistance, differs amongst various viruses.  相似文献   

Progress in aphid forecasting systems     

R. Sigvald 《European journal of plant pathology / European Foundation for Plant Pathology》1992,98(2):55-62

Potato virus Y and many other viruses of potatoes cause major economic losses to seed potato production in many countries. Potato virus Y, which is transmitted in a non-persistent manner, is one of the most important virus diseases of potatoes in many countries in Europe and especially in the northern regions.During the last decade there has been an increasing interest in developing methods for potato virus forecasting. The abundance of virus vectors is often estimated by yellow water traps (YWT), suction traps or field surveys. In Sweden the relationship between occurrence of alate aphids and the proportion of PVY infected progeny tubers has been studied since 1975. A dynamic simulation model for PVY has been designed for predicting the incidence of PVY. The simulation model describes a system which includes e.g., healthy and PVY diseased potato plants, different aphid species as virus vectors an their efficiency as virus vectors, the susceptibility of the potato crop according to mature plant resistance and date of haulm destruction. There was a good correlation between model output and samples of progeny tubers tested for PVY.  相似文献   

Alarm pheromones and allelochemics as a means of aphid control     

E. Herrbach 《European journal of plant pathology / European Foundation for Plant Pathology》1992,98(2):63-71

The relevance of studies on aphid-plant relationships for plant virus epidemiology is highlighted. Many behavior-modulating chemicals (semiochemicals) play a major role in intraspecific (pheromones) or interspecific (allelochemics) interrelations and therefore offer opportunities to interfere with virus transmission. Present knowledge on the role of semiochemicals in different behavioral events is emphasized using examples (alarm and sex pheromones, allelochemics involved in host selection, antifeedants) and their potential for controlling virus transmission and spread is discussed.  相似文献