Nutritional evaluation of some Bangladeshi oilseed meals as partial substitutes for fish meal in the diet of common carp, Cyprinus carpio L.

Abstract. Three oilseed meals (mustard, linseed and sesame) of Bangladeshi origin were evaluated as fish meal substitutes in diets of common carp, Cyprinus carpio L. These oilseed meals were included in the diet at various levels (25, 50 and 75% of dietary protein) and the response of fish fed these diets was compared to fish fed a fish meal based control diet (40% protein). On the basis of observed growth rate, food conversion ratio, protein efficiency ratio and apparent net protein utilization, the control diet produced significantly (P< 0.05) the best growth performance. Growth responses were significantly affected by both type and inclusion level of oilseed protein. Of the oilseed proteins tested, the 25% mustard protein and 25% linseed protein diets produced significantly (P< 0.05) better growth performances than higher inclusion levels tested. Apparent protein digestibilities (APDs) for all diets were fairly high, ranging from 77.72 to 89.8O%. In general, APD values decreased with increasing plant protein. Fish fed diets containing higher levels of oilseed protein had significantly (P< 0.05) higher carcass moisture and lower carcass lipid contents. Fish fed 50% mustard protein had histological abnormalities in liver and thyroid tissues. Results are discussed with respect to dietary levels of essential amino acid and anti-nutritional factors.     

Experience of partnership models for the co-management of Bangladesh fisheries

Failure in the past to ascertain responsible fishing practices and equitable distribution of benefits under traditional leasing systems has motivated the Bangladesh government to work in partnership with non-governmental organizations (NGOs) and fishing communities in recent times. This paper discusses the operational approaches that were used to identify fishing people and create institutions for their increasing participation in local fisheries, and in making and enforcing resource use rules under various partnership arrangements. The group-based empowerment strategies of NGOs; their role in securing for the beneficiaries the access rights to water bodies; the provision of credits and inputs for employment and income generation activities showed some practical evidence of the concept of the poor as managers of the fisheries resources. The policy issues involved in the rights of local community members to catch fish for subsistence are also discussed, as well as the challenges associated with the difficulties of reconciling differing government (GO) and nongovernment (NGO) organization priorities and points of view with regard to target group identification and levels of responsibilities.     

Effect of standing water and shoot removal plus standing water regimes on growth, regrowth and biomass production of torpedograss (Panicum repens L.)

The present study was undertaken from May 1996 to October 1997 in the glasshouse of the University of the Ryukyus, Okinawa, Japan to investigate standing water (12 cm deep) and shoot removal plus standing water regimes on morphological changes, growth, regrowth and biomass production of torpedograss ( Panicum repens L.). The stem internode was longer in standing-water-treated plants than that in untreated plants. The root-crown was developed from the submerged stem-node. Spike-like tillers and sheath-like leaf blades were observed in water-treated plants. Higher shoot biomass and lower rhizome biomass were obtained in standing-water-treated plants than that in untreated plants. Standing-water-treated plants attained higher total biomass than untreated plants. Standing-water stress was the factor that inhibited regrowth of torpedograss when the above-ground shoot was removed. Rhizomes without shoots of 6-month-old torpedograss did not survive in standing water for more than 6 months. The results indicate that torpedograss can survive in standing water if the shoots remain above the water surface. Shoot removal is one effective way to control torpedograss regrowth in standing water. The results of this study may be dependent on season, day length, water temperature, water pH, water depth and salt concentration in water.     

接种根瘤菌对白格、大叶合欢和银合欢生长与结瘤的影响

Effects of inoculation of Rhizobium suspension on nodulation and plant growth were examined with Albizzia procera,Albizzia lebbeck and Leucaena leucocephala seedlings grown on sterilized and non-sterilized soil media.Inoculation resulted in nodule number increases of 28.6,29.02and 23.9 times in sterilized soil and 3.4,3.6and 3.27 times in non-sterilized soil for A.procera,A.lebbeck and L.leucocephala seedlings respectively.Total dry mass increased by 127.6%,66.7%and 60.7% in sterilized soil and 100%,95.5%and 52.65% in non-sterilized soil for these three legume trees,respectively,after a period of two months.Significantly high inoculation responses of oot length,root diameter,collar diameter,shoot length,and dry mass of root,shoot,leaves and nodules were also observed in both steilized and non-sterilized soil media as compared to respective control treatments,The response to inoculation was strong in sterilized and modest in non-sterilized soils.The significantly higher response to Rhizobium inoculation over control in all the species tested suggested that application of Rhizobium greatly enhanced plant growth ,nodulation,biomass production and nitrogen-fixing activity of the nodules.     

土壤生物炭的生产：三种窑模型的比较研究

Biochar has potentials for soil fertility improvement, climate change mitigation and environmental reclamation, and charred biomass can be deliberately incorporated into soil for long-term carbon stabilization and soil amendment. Many different methods have been used for biochar production ranging from laboratory to industrial scales. However, in countryside of developing countries,biomass is generally used for cooking but not charred. Biochar production techniques at farmer scale have remained poorly developed.We developed and tested biochar production kilns for farmers with a dimension of 50.8 cm × 38.1 cm(height × diameter), using three different setups for optimizing oxygen(O2) limitation and syngas circulation: airtight with no syngas circulation(Model I),semi-airtight with external syngas circulation(Model II) and semi-airtight with internal syngas circulation(Model III). A comparative assessment of these biochar production kiln models was made considering biochar pyrolysis time, fuel to biomass ratio, biochar to feedstock ratio and thermogravimetric index(TGI). Among the models, the best quality biochar(TGI = 0.15) was obtained from Model I kiln taking the longest time for pyrolysis(12.5 h) and the highest amount of fuel wood(1.22 kg kg-1biomass). Model III kiln produced comparatively good quality biochar(TGI = 0.11), but with less fuel wood requirement(0.33 kg kg-1biomass) and shorter pyrolysis time(8.5 h). We also tested Model III kiln in a three times larger size under two situations(steel kiln and pit kiln). The biochar to feedstock ratio(0.38) and quality(TGI = 0.14) increased slightly for the larger kilns. Quality of biochar was found to be mainly related to pyrolysis time. The costs for the biochar stove and pit kiln were US$ 65–77, while it was US$ 154 for the large size steel kiln. Model III kiln can potentially be used for both cooking and biochar production at farmer scale.     

Biological nitrification inhibition by Brachiaria humidicola roots varies with soil type and inhibits nitrifying bacteria, but not other major soil microorganisms

The tropical pasture grass Brachiaria humidiola (Rendle) Schweick releases nitrification inhibitory compounds from its roots, a phenomenon termed 'biological nitrification inhibition' (BNI). We investigated the influence of root exudates of B. humidicola on nitrification, major soil microorganisms and plant growth promoting microorganisms using two contrasting soil types, Andosol and Cambisol. The addition of root exudates (containing BNI activity that is expressed in Allylthiourea unit (ATU) was standardized in a bioassay against a synthetic inhibitor of nitrification, allylthiourea, and their function in soil was compared to inhibition caused by the synthetic nitrification inhibitor dicyandiamide. At 30 and 40 ATU g⁻¹soil, root exudates inhibited nitrification by 95% in fresh Cambisol after 60 days. Nitrification was also similarly inhibited in rhizosphere soils of Cambisol where B. humidicola was grown for 6 months. Root exudates did not inhibit other soil microorganisms, including gram-negative bacteria, total cultivable bacteria and fluorescent pseudomonads. Root exudates, when added to pure cultures of Nitrosomonas europaea , inhibited their growth, but did not inhibit the growth of several plant growth promoting microorganisms, Azospirillum lipoferum , Rhizobium leguminosarum and Azotobacter chroococcum. Our results indicate that the nitrification inhibitors released by B. humidicola roots inhibited nitrifying bacteria, but did not negatively affect other major soil microorganisms and the effectiveness of the inhibitory effect varied with soil type.     

Factors affecting the seed germination and seedling emergence of redflower ragleaf (Crassocephalum crepidioides)

Redflower ragleaf (Crassocephalum crepidioides) is a weed, as well as a minor vegetable, in tropical and subtropical regions of the world. The influence of environmental factors and seed conditions on the germination and emergence of redflower ragleaf have been evaluated in order to help understand its distribution and to develop effective management strategies. The seeds germinated at a constant temperature in the range of 10–30°C and reached a maximum at 15–20°C. The highest germination rate was recorded at an alternating temperature of 20/15°C (day/night). The seeds germinated over a wide pH range (2–12), with the highest germination rate at between 4 and 10. Germination under saturated and flooded conditions was also high. The germination of seeds from opened (mature) capitula was significantly higher than from partially opened or unopened capitula. The germination of seeds without a pappus was significantly higher than for seeds with a pappus. The germination rate of 1 year old seeds decreased drastically when compared to that of freshly harvested seeds. The seedling emergence rate was ～63% for those seeds placed on the soil surface, but no seedling emerged from a depth of ≥1 cm. These results indicate that redflower ragleaf seeds can germinate in various environmental conditions, but that the percentage that germinates will be different in different environments. Regeneration could be effectively prevented by at least a 1 cm soil covering or by destroying the plant before the capitula open. In contrast, freshly harvested seeds from opened capitula should be sown on the soil surface when redflower ragleaf is to be cultivated as a vegetable.     

废水污泥生物炭对圣女果生长、产量及重金属累积效应的对比评估

To investigate the potential effects of wastewater sludge and sludge biochar on growth, yield and metal bioaccumulation of cherry tomato ({\it Lycopersicon esculentum} L.), a pot experiment was carried out under greenhouse environment with three different treatments, control soil (CP), soil with wastewater sludge (SS) and soil with sludge biochar (SB), to reveal the comparative effect between the amendments of wastewater sludge and sludge biochar.~The soil used for pot experiment was Chromosol.~Wastewater sludge and sludge biochar produced through pyrolysis process at 550 $^\circ$C were applied at 10 t ha$^{-1}$. No significant difference was found in growth and production of cherry tomatoes between wastewater sludge and sludge biochar applications to the soil. The accumulation rates of metals in the fruits were lower in the treatment with sludge biochar than in the treatment with wastewater sludge. The study highlights the benefits of risk mitigation from toxic metal accumulation in fruits using wastewater sludge and sludge biochar as soil conditioners.