Climate Change Impacts on a Tropical Fishery Ecosystem: Implications and Societal Responses

The present study aimed to map out the current threats and anticipated impacts of climate change on the most important hilsa shad (Tenualosa ilisha) fishery and the associated fishing communities based on fieldwork in six coastal fishing communities. To collect empirical data, individual interviews, focus group discussions, oral history, and key informant interviews were conducted. To supplement the empirical findings, time-series data of cyclones and sea-borne depressions in the Bay of Bengal were also analyzed. Analysis of secondary data regarding climate change-induced events and regional studies suggested that the biophysical conditions of the Bay of Bengal are likely to be aggravated in the future, potentially causing more frequent extreme events and affecting the livelihoods of coastal fishing communities in Bangladesh. The fisher respondents revealed that the main target hilsa shad fishery is particularly vulnerable to climate change in terms of alterations to migration patterns and breeding and growth performance. The fishers reported constant climate-related risks because they live in seafront locations, exposed to extreme events, and their occupation entails risky sea fishing. Fishers claimed that they often need return to the coast due to unsuitable weather conditions related to cyclones and frequent tropical depressions, which can cause financial losses or even causalities. Such events negatively affect fishers’ livelihoods, and wellbeing. To cope with the impacts of climate change the fishers have adopted various strategies at both sea fishing and household levels. However, these strategies only support the fishers in terms of immediate survival; they are not enough for long-term resilience. To improve the resilience of the hilsa fishers, the study argues for the implementation the Small-Scale Fisheries Guidelines (SSF Guidelines), which call for longer-term development goals, including in the immediate relief phase, and rehabilitation, reconstruction, and recovery to reduce vulnerabilities to climate and anthropogenic risks

DNA Fingerprinting and Genotyping of Cotton Varieties Using SSR Markers

DNA fingerprinting and genetic diversity analysis helps direct selective breeding and conservation of plant species. Since simple sequence repeats (SSR) markers are co-dominant, they can predict level of genetic diversity and thereby protect plant genetic resources of a region. Keeping the aforesaid rationale in mind, we worked on molecular characterization of eight cotton varieties in Bangladesh using simple sequence repeat (SSR) or microsatellite DNA markers. All the three microsatellite DNA markers were found to be polymorphic, extracting a total of eight alleles with an average of 2.67 alleles per locus in the present study. Allele sizes were as 149-155 bp, 178-198 bp and 140-202 bp for the loci BNL1551, BNL1721 and BNL2960, respectively. Polymorphism Information Content (PIC) values were ranged from 0.469 to 0.531. UPGMA dendrogram separated 8 varieties of cotton into two clusters. One cluster contained six varieties CB-1, CB-2, CB-3, CB-7, CB-9 and CB-10 while other two varieties CB-5 and HC 1 formed another cluster. The findings of this study would provide a useful guide for selecting specific germplasm with distinct genetic background for diversifying cotton breeding program in Bangladesh

Screening of Salt Tolerant Potato Genotypes using Salt Stress and Molecular Markers

Aims: To screen potato genotypes for salt tolerance using in vitro salt stress and moleulcar markers. Experimental Design: The experiment was arranged in Completely Randomized Design (CRD) with three replications. Place of the Study: The experiment was conducted at the Molecular Biology and Tissue Culture Laboratories, Institute of Biotechnology and Genetic Engineering, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh. Methodology: In vitro screening of five potato genotypes (CIP 112, CIP 117, CIP 120, CIP 127, and CIP 128) was done in an agar medium using tissue culture technique at different concentrations of salt viz. 0.0, 10, 20, 40, 60, 80, 100, 120 mM of NaCl. All genotypes were further analysed through SSR markers using three primers. The DNA bands were visualized on gel electrophoresis and scored for polymorphic loci, gene diversity, and genetic distance. NTSYSpc program was used for constructing  unrooted neighbor-joining tree and scatter diagram. Results: Potato genotypes CIP 112 and CIP 117 emerged as the most salt tolerant genotypes with the highest plant height, shoot dry weight, root length, and root dry weight at different concentrations of NaCl. CIP 127 and CIP 128 were poorly tolerant to salt stress. The most sensitive genotype CIP 120 produced minimum plant height, shoot dry weight, root length, and root dry weight at different NaCl concentrations. Results indicated that significant differences were found among cultivars. The banding pattern of microsatellite confirmed a distinct polymorphism among salt tolerant, moderately salt tolerant and salt sensitive lines. The clustering pattern of the potato genotypes suggests that variations occur due to genotypic variation and possibly not epigenetic adaptation under salt stress conditions. Conclusion: The salt tolerant pototo genotypes CIP 112 and CIP 117 can be used for developing salt tolerant genotypes

Understanding the political ecology of forced migration and deforestation through a multi-algorithm classification approach: the case of Rohingya displacement in the southeastern border region of Bangladesh

Compared with numerous existing forced migration scenarios across the globe, migration from Myanmar to Bangladesh through southeastern border region is unique at least for three reasons – (i) very large number of migrants have been displaced to (ii) a very small area in (iii) a relatively short period of time, creating an obvious cumulative impact on forest cover area of the host country. Therefore, this study aims to analyze the dynamics of refugee migration and deforestation in Bangladesh. Satellite images of Landsat-5 & 8 and Sentinel-2 were classified via four different classification algorithms (SVM, Random Forest, CART, and Max Entropy) to measure major land use and land cover changes, namely, (i) dense forest, (ii) sparse forest, (iii) open area, and (iv) settlement from 1988 to 2018. The analysis revealed a declining trend of dense forest area, majority of which took place from 2016 to 2018 triggered by Rohingya migration. As a whole, the dense forest cover has been effectively halved (8531 ha in 2016 to 4498 ha in 2018) in the span of just two years while refugee settlement has increased nine-folds (271 ha in 2016 to 2679 ha in 2018). Aggregated and indisputable conclusion has been derived indicating that forced Rohingya migration and deforestation are indeed positively correlated

Integrated management of Fusarium wilt of chickpea (Cicer arietinum L.) caused by Fusarium oxysporum f. sp. ciceris with microbial antagonist, botanical extract sp. ciceris with microbial antagonist, botanical extract

The present study was carried out to assess the efficacy of an integrated management strategy for Fusarium wilt of chickpea that combined the use of microbial antagonist, botanical extract and fungicide. Before setting the experiment in field micro plots, a series of in vitro and in vivo experiments were conducted to select a virulent isolate of F. oxysporum f. sp. ciceris, an effective antagonistic isolate of Trichoderma harzianum, a fungitoxic botanical extract and an appropriate fungicide. The isolate FS1 of F. oxysporum f. sp. ciceris appeared to be most virulent to chickpea cultivar BU-Chola-1 and selected as test pathogen. Among the 20 isolates screened, T. harzianum isolate T-75 showed the highest (75.89%) inhibition of the radial growth of F. oxysporum f. sp. ciceris in dual culture assay on PDA. Absolute inhibition (100.00%) of colony growth of F. oxysporum f. sp. ciceris was observed where fungicide Provax-200 at 100 ppm was used. Azadirachta indica leaf extract gave maximum inhibition (55.19%) of radial growth of F. oxysporum f. sp. ciceris at all concentrations. The integration of soil treatment with T. harzianum isolate T-75 and Az. indica leaf extract and seed treatment with Provax-200 appeared to be significantly superior in reducing Fusarium wilt and in improving seed yield of chickpea compared to any single or dual application of them in the field. The results of this study exhibit the importance of integrating selective microbial antagonist, botanical extract and fungicide to achieve appropriate management of Fusarium wilt and increase of seed yield in chickpea in Bangladesh.Keywords: Integrated management, Fusarium wilt, Fusarium oxysporum f. sp. ciceris, chickpea (Cicer arietinum L.), antagonists, botanicals, fungicides.African Journal of Biotechnology Vol. 12(29), pp. 4699-470

Biocontrol potential of native isolates of Beauveria bassiana against cotton leafworm Spodoptera litura (Fabricius)

Abstract The entomopathogenic fungus (EPF), Beauveria bassiana, is reported as the most potent biological control agent against a wide range of insect families. This study aimed to isolate and characterize the native B. bassiana from various soil habitats in Bangladesh and to evaluate the bio-efficacy of these isolates against an important vegetable insect pest, Spodoptera litura. Seven isolates from Bangladeshi soils were characterized as B. bassiana using genomic analysis. Among the isolates, TGS2.3 showed the highest mortality rate (82%) against the 2nd instar larvae of S. litura at 7 days after treatment (DAT). This isolate was further bioassayed against different stages of S. litura and found that TGS2.3 induced 81, 57, 94, 84, 75, 65, and 57% overall mortality at egg, neonatal 1st, 2nd, 3rd, 4th, and 5th instar larvae, respectively, over 7 DAT. Interestingly, treatment with B. bassiana isolate TGS2.3 resulted in pupal and adult deformities as well as decreased adult emergence of S. litura. Taken together, our results suggest that a native isolate of B. bassiana TGS2.3 is a potential biocontrol agent against the destructive insect pest S. litura. However, further studies are needed to evaluate the bio-efficacy of this promising native isolate in planta and field conditions

Pseudomonas and Burkholderia inhibit growth and asexual development of Phytophthora capsici

The objective of this study was to isolate and characterize antagonistic rhizobacteria from chili against a notorious phytopathogen Phytophthora capsici. Among the 48 bacteria isolated, BTLbbc-02, BTLbbc-03, and BTLbbc-05 were selected based on their inhibitory activity against P. capsici. They were tentatively identified as Burkholderia metallica BTLbbc-02, Burkholderia cepacia BTLbbc-03, and Pseudomonas aeruginosa BTLbbc-05, respectively, based on their 16S rRNA gene sequencing. All inhibited the growth of P. capsici at varying levels by inducing characteristic morphological alterations of P. capsici hyphae. The cell-free culture supernatant of all three isolates impaired motility (up to 100%) and caused lysis (up to 50%) of the halted zoospores. Bioassays revealed that Pseudomonas sp. had higher antagonism and zoospore motility-inhibitory effects against P. capsici compared with two other isolates, Burkholderia spp. and B. metallica, which caused vacuolation in mycelium. All three bacteria suppressed sporangium formation and zoosporogenesis of P. capsici, and improved the seed germination and growth of cucumber. Our findings suggest that epiphytic bacteria, B. metallica, B. cepacia, and P. aeruginosa, could be used as potential biocontrol agents against P. capsici. A further study is required to ensure conformity with the existing regulations for soil, plant, and human health

Sphingomonas panaciterrae PB20 increases growth, photosynthetic pigments, antioxidants, and mineral nutrient contents in spinach (Spinacia oleracea L.)

Plant growth promoting rhizobacteria (PGPR) have been intensively investigated in agricultural crops for decades. Nevertheless, little information is available on the application of Sphingomonas spp. as a PGPR particularly in vegetables, despite of potential plant growth promoting traits of this group. This study investigated the role of Sphingomonas panaciterrae (PB20) on growth and nutritional profile of spinach applied through seed priming (SP), soil drenching (SD), foliar application (FA), and bacterial culture filtrate foliar (BCF) applications. The results showed that, depending on different methods of application, PB20 significantly increased plant height (19.57–65.65 %), fresh weight (7.26–37.41 %), total chlorophyll (71.14–192.54 %), carotenoid (67.10–211.67 %) antioxidant (55.99–207.04), vitamin C (8.1–94.6 %) and protein content (6.7–21.5 %) compared to control in the edible part of spinach. Among the mineral nutrients, root nitrogen (N) showed greater response to bacterial application (18.65%–46.15 % increase over control) than shoot nitrogen (6.70%–21.52 % increased over control). Likewise, in all methods of application, phosphorus (P) content showed significant increase over control both in root (42.79–78.48 %) and in shoot (3.57–27.0 %). Seed priming and foliar application of PB20 increased the shoot calcium (Ca) content compared to control. BCF foliar application yielded maximum magnesium (Mg), iron (Fe) and zinc (Zn) in shoot. However, seed priming resulted in maximum Fe in root. Overall, seed priming outperformed in growth, vitamin C, antioxidants, N and P uptake, while BCF foliar application resulted in better uptake of several nutrients. Multivariate analysis validated the positive association of most of the growth parameters with SP while several nutrients with FA and BCF. Based on the findings it is evident that this rhizobacteria PB20 has the potentiality to be applied as a biofertilizer to produce nutrient-enriched spinach with an improved yield. Farmers can conveniently incorporate PR20 through seed priming before planting of spinach, with additional benefits through foliar spray