[en] Microbiological studies of sun-dried mackerel fish, Cybium guttatum, were conducted by exposing the fish to doses of gamma-rays from 0.50 to 8.00 kGy at the storage temperatures of 10.20 and 30oC. The reduction of bacterial flora was determined both qualitatively and quantitatively. At 4 kGyone log cycle reduction of bacterial flora was achieved and at 8 kGy the reduction was nearly 2 log cycles. The irradiated samples were stored for two months and viable bacterial counts were taken. Except in a few cases, reduction in viable counts occurred. Bacterial isolates were made and both Mesophiles and Psychrophiles were identified. Micrococcus, Staphylococcus, Corymebacterium and some Bacillus were found to be the prominent groups in mesophiles, while Bacillus dominated in psychrophiles. Staphylococcus was found to be the most dominant bacterial flora in unirradiated samples, but they were highly affected by irradiation

[en] In order to improve the yielding potential of chickpea in Bangladesh, both induction of mutations and collection of local and exotic germplasm have been undertaken. This paper presents the number and type of variants obtained in the M₂, performance of M₂ plant-progeny rows in the M₃ and also the yielding potential of the selected mutants in the M₄ generation compared to the collected germplasm. (author)

[en] Disinfestation of dried fish and sprout inhibition of onions were undertaken by radiation on a semi-commercial scale to evaluate the commercial performances, storage quality and consumer acceptability. Irradiation of dried fish at 1 kGy was found to be effective for disinfestation and for a reduction in the microbial populations. Control and irradiated dried fish were transported to Indonesia and Sri Lanka and studied there, as part of inter-country storage and transportation trials. Similar lots were transported 600 km by road. The organoleptic properties evaluated by subjective methods indicated the superior quality of the irradiated product. The pertinent chemical parameters were also studied to identify the commercial qualities of irradiated dried fish. Favourable reports on consumer assessment of product quality were received when irradiated dried fish was market tested through the usual marketing channels in Dhaka and Chittagong. Studies on the transportation behaviour and market testing of the experimental onions were undertaken in Dhaka and Chittagong during the lean period, in co-operation with a commercial entrepreneur, to evaluate the commercial performance and consumer assessment of the product quality. The results indicated that the process inhibited sprouting and reduced storage losses, and that consumers assessed the quality of irradiated onions favourably. 9 refs, 4 figs, 9 tabs

[en] Presently grown varieties of pulses in Bangladesh are low yielding. Traditionally they are grown under marginal conditions. Restructuring of yield components might lead to more productive genotypes. A mutation breeding programme was started to create genetic variability for yield components among locally adapted and introduced cultivars of mungbean, blackgram, lentil and chickpea. Irradiation effects upon M₁ generation are reported. (author)

[en] Effect of radiation on different developmental stages of mites, thrips, and nematodes were observed to determine their sterility doses and to develop a method for detection of irradiated and unirradiated specimens. A brief survey on cut-flower and tuber associated pests, and their biological study along with the tolerance level of host products were conducted. Mites Oligonychus biharensis (Hirst) and Tetranychus sp., as well as four species of thrips viz. Retithrips syriacus (Mayet), Haplothrips gowdeyi Franklin, Frankliniella intonsa Tribom, and Microcephalothrips abdominalis Crowford were recognized as common pests damaging plants and cut-flowers. Common species of nematodes infesting ginger and turmeric were Meloidogyne spp. and Ditylenchus spp. Results indicated that a dose 0.2 kGy and above caused complete sterility of male and female mites and insects. Various pre-adult developmental stages required less irradiation dose (0.05-0.1 kGy) for sterilization. Variation of melanization in treated and untreated life stages of mites and thrips could not be observed even at 0.2 kGy with the 2-methyl DOPA spot test. Inhibition of melanization in irradiated pupal stages of thrips were observed at doses above 0.4 kGy. Both irradiated and unirradiated thrips were identical in their protein banding pattern. Virtually no protein bands were observed in irradiated and unirradiated nematodes when samples were run on 5% PAGE in TBE. Tube rose and marigold treated with higher dose (0.3 to 0.5 kGy) caused no remarkable morphological degradation for 7-8 days after irradiation. Nematodes were resistant to radiation. Complete elimination and abnormalities of J₂ stages of Meloidogyne spp. and Ditylenchus spp. were not observed even at 4.0 kGy although significant weight loss and spoilage of tubers were recorded after 14 days of radiation exposure. (author)

No abstract available

[en] Dried and cured fishery products, onions and potatoes face enormous storage losses in Bangladesh due to insect infestation and sprouting. Research and development work was carried out to assess the suitability of introducing irradiation processing of these products in the country. Experiments showed that a dose of 0.04-0.68 kGy could inhibit sprouting in onions. Sprouting in potatoes could be inhibited at 0.10 kGy. Dried and cured fishery products could be disinfested of insects at a dose of 0.30 kGy. Infrastructure such as transportation, storage, marketing and existing systems of post-harvest handling were analysed. Post-harvest storage losses of onion and dried fish were more than 50% after 6 months of storage. Potatoes could not be kept at ambient conditions for over 3 months after the harvesting season. Irradiation of onions and dried fish, if they were stored in suitable conditions after proper packaging, could save significant storage losses. Irradiated potatoes could be stored at 14 deg. C instead of 2-4 deg. C as practised normally. On the basis of the data collected on dried and cured fishery products, onions and potatoes, economic feasibility studies were conducted. Assumptions for calculation of cost of the irradiation facility were: (i) strength of the irradiator source: 7.40 PBq of ⁶⁰Co; (ii) construction period: 2 years; (iii) operating time: 7200 hours per year; (iv) economic life: 20 years; (v) capacity utilization: 80-90%. In addition to dried and cured fish, potatoes and onions, this facility would also treat fresh fish and medical products in order to maximize its use. It would have an investment cost of US $1.9 million. The payback period was found to be less than 4 years. If additional warehouses could be built along with the facility, such a venture would be more profitable. 23 refs, 8 figs, 28 tabs

[en] A large quantity of dried fish is lost in Bangladesh due to infestation by earwigs, hide beetles and copra beetles in storage godowns. The most destructive pest is the hide beetle, Dermestes maculatus Deg. Earwigs of different developmental stages were exposed to 0.10, 0.20 or 0.30 kGy of gamma rays for disinfestation. There was apparent damage to the control but all treated samples were in good condition and no live insect was observed 3 weeks after starting the experiment. Disinfestation studies of dried mackerel showed that eggs, larval and pupal stages of hide beetles could be inactivated at a dose of 0.20 kGy. A dose of 0.30 kGy killed all adults 2 weeks after irradiation. In the packaging studies, dried mackerel was packed in polythene pouches of different thicknesses. Two controls were maintained, i.e. dried fish with no treatment, control, and dried fish disinfested with heat at 60 deg. C, disinfested control. In experiments with 50 μm thick polythene pouches, the dried fish of irradiation treatments with 0.10 to 1.0 kGy doses and the controls had around 20% moisture content with the exception of disinfested controls which had 13% moisture content. All irradiated samples were free from insect damage. There was heavy damage in the controls due to insects. However, all these treated fish had heavy fungal growth with the exception of the disinfested control. Similar results were obtained with pouches made of 75 μm thick polythene irradiated at doses of 0.50, 1.0, 2.0 and 4.0 kGy. In the final experiments pouches were made of 50, 75 and 100 μm thick polythene and exposed to similar radiation as in the previous experiment. In all the treatments, moisture content was reduced to 13%. heavy insect damage was observed in the control, while all the treated samples were in excellent condition after 5 months of storage. (author). 20 refs, 2 figs, 5 tabs

[en] The bruchid beetles Callosobruchus chinensis (L.) and C. analis Fab. were found to infest different varieties of pulses, i.e. lentil (Lens culinaris (Med.)), mung (Vigna radiatus L.) and mashkalai (Phaseolus radiatus L.). Radiation sensitivity studies on the pulse beetles showed that a dose of 0.04 kGy stopped adult emergence from the eggs. Doses of 0.28 and 0.32 kGy were required at the 4th larval instar to inhibit adult emergency of C. analis and C. chinesis, respectively. The oilseeds, mustard (Brassica campestris L.) and til (Sesamum indicum L.), were infested with the Angoumois grain moth, Sitotroga cerealella (Olivier), the saw toothed grain beetle, Oryzaephilus surinamensis (L.), and the cigarette beetle, Lasioderma serricorne (F.). Radiosensitivity studies on the eggs, larvae and pupae of S. cerealella and O. surinamensis revealed that a dose of 0.4 kGy is sufficient for complete inhibition of metamorphosis. Radiosensitivity studies of the cigarette beetle showed that a dose of 0.05 kGy stopped adult emergence from the irradiated eggs, and 0.2 kGy from the irradiated larvae. At 0.5 kGy, the emergence of adults from the irradiated pupae was 36%, but all died within 7 days. In packaging studies, the experimental results showed that jute bags lined with polyethylene (0.1 mm) and treated with permethrin (80-100 mg/m²) on the outer layer provided full protection from infesting insects for 8 months of storage. Treatment of pulses, oilseeds and tobacco leaves with irradiation (1 kGy) and phostoxin (126 mg/10,000 ft³) produced almost the same results. Although the irradiation costs were found to be higher than fumigation, this could be reduced by decreasing the effective irradiation dose to 0.5 kGy and by increasing the efficiency of irradiator utilization. 7 refs, 12 tabs

No abstract available