Rice is the world's most important food crop, providing the daily calorie intake for more than half of the world's population. Rice breeding has always been preoccupied with maximizing yield potential. However, numerous abiotic factors, such as salt, cold, drought, and heat, significantly reduce rice productivity. Salinity, one of the major abiotic stresses, reduces rice yield worldwide. This study was conducted to determine new quantitative trait loci (QTLs) that regulate salt tolerance in rice seedlings. One F2:3 mapping population was derived from a cross between BRRI dhan49 (a popular but sensitive rainfed rice variety) and Akundi (a salt-tolerant rice landrace in Bangladesh used as a donor parent). The 1k-Rice Custom Amplicon (1k-RiCA) single-nucleotide polymorphism (SNP) markers were used to genotype this mapping population. After removing segregation distortion and monomorphic markers, 884 SNPs generated a 1526.8 cM-long genetic linkage map with a mean marker density of 1.7 cM for the 12 linkage groups. By exploiting QGene and ICIM-ADD, a sum of 15 QTLs for nine traits was identified in salt stress on seven chromosomes. Four important genomic loci were identified (qSES1, qSL1, qSUR1 and qRL1) on chromosome 1. Out of these 15 QTLs, 14 QTLs are unique, as no other study has mapped in the same chromosomal location. We also detected 15 putative candidate genes and their functions. The ICIM-EPI approach identified 43 significant pairwise epistasis interactions between regions associated with and unassociated with QTLs. Apart from more well-known donors, Akundi serves as an important new donor source for global salt tolerance breeding initiatives, including Bangladesh. The introgression of the novel QTLs identified in this study will accelerate the development of new salt-tolerant varieties that are highly resistant to salt stress using marker-enabled breeding.
The faba bean is among the major grain legumes cultivated in Ethiopia and is used extensively as a break crop in the highlands. Although a blanket application of DAP (diammonium phosphate) at the rate of 100 kg · ha −1 has been practised in faba bean production in the country, this was not based on research results. In addition, little information is available on the response of the crop to N and P fertilizers under diverse environmental conditions. Hence, field experiments were carried out at three locations in 1991, seven locations during 1992 and 1993 and at one location in both 1993 and 1995 to determine faba bean response to N and P fertilization. Five levels of N (0, 9, 18, 27 and 36 kg N · ha −1 as urea) in factorial combinations with four levels of P (0, 23, 46 and 69 kg P 2 O 5 · ha −1 as TSP [triple super phosphate]) were studied in a randomized complete block design with four replications in the first year. In the remaining years four levels of N (0, 18, 27 and 36 kg N · ha −1 as urea) in factorial combinations with four levels of P (0, 23, 46 and 92 kg P 2 O 5 · ha −1 as TSP) were used in a randomized complete block design with three and four replications at one and seven locations, respectively. Results indicated that a positive linear response of faba bean seed yield was noted at all locations (except Debre Zeit and Burkitu) to P fertilization, while a significant quadratic response was also found at Holetta. In addition, plant height, above ground biomass and number of pods per plant were positively influenced by P application while the effect of N on these was mostly nonsignificant. Faba bean seed yield response to N was noted at only two out of eight locations; in most cases, nonsignificant and inconsistent seed yield responses to N fertilization were obtained. There was nonsignificant N × P rate interaction. In conclusion, we do not recommend supplemental N application to faba bean at six out of eight locations but we recommend the application of P fertilizer to faba bean at almost all locations (with the exception of Debre Zeit) and for other soils deficient in available P. Further work is recommended on the determination of critical levels for soil‐available P, below which P fertilization should be practised for optimum faba bean seed yield.
Achieving high-yield potential is always the ultimate objective of any breeding program. However, various abiotic stresses such as salinity, drought, cold, flood, and heat hampered rice productivity tremendously. Salinity is one of the most important abiotic stresses that adversely affect rice grain yield. The present investigation was undertaken to dissect new genetic loci, which are responsible for salt tolerance at the early seedling stage in rice. A bi-parental mapping population (F2:3) was developed from the cross between BRRI dhan28/Akundi, where BRRI dhan28 (BR28) is a salt-sensitive irrigated (boro) rice mega variety and Akundi is a highly salinity-tolerant Bangladeshi origin indica rice landrace that is utilized as a donor parent. We report reliable and stable QTLs for salt tolerance from a common donor (Akundi) irrespective of two different genetic backgrounds (BRRI dhan49/Akundi and BRRI dhan28/Akundi). A robust 1k-Rice Custom Amplicon (1k-RiCA) SNP marker genotyping platform was used for genome-wide analysis of this bi-parental population. After eliminating markers with high segregation distortion, 886 polymorphic SNPs built a genetic linkage map covering 1526.5 cM of whole rice genome with an average SNP density of 1.72 cM for the 12 genetic linkage groups. A total of 12 QTLs for nine different salt tolerance-related traits were identified using QGene and inclusive composite interval mapping of additive and dominant QTL (ICIM-ADD) under salt stress on seven different chromosomes. All of these 12 new QTLs were found to be unique, as no other map from the previous study has reported these QTLs in the similar chromosomal location and found them different from extensively studied Saltol, SKC1, OsSalT, and salT locus. Twenty-eight significant digenic/epistatic interactions were identified between chromosomal regions linked to or unlinked to QTLs. Akundi acts like a new alternate donor source of salt tolerance except for other usually known donors such as Nona Bokra, Pokkali, Capsule, and Hasawi used in salt tolerance genetic analysis and breeding programs worldwide, including Bangladesh. Integration of the seven novel, reliable, stable, and background independent salinity-resilient QTLs (qSES1, qSL1, qRL1, qSUR1, qSL8, qK8, qK1) reported in this investigation will expedite the cultivar development that is highly tolerant to salt stress.
Abstract Heavy metals (Pb, Cd, Ni, Cr, Cu, Zn, Mn, and As) concentration was investigated in the industrial effluents, water, sediment, and fish samples collected around the Dhaka Export Processing Zone, Savar, Bangladesh, to evaluate the level of contamination. The metals concentration in the industrial effluents of DEPZ and in the water samples of Dhalaibeel (lowland cum lake) and Bangshi River were significantly higher compared to the guideline values for industrial effluents and for drinking water (WHO and USEPA), respectively. The sedimentary metal concentrations were found to be lower than the respective probable effect concentrations (PECs) following the sediment quality guidelines. Furthermore, in comparison with the fish standards, the studied fish species were not found to be contaminated by heavy metals. Principal component analysis and cluster analysis demonstrated that the wastewater from the numerous industries and the domestic sewages around the DEPZ might have a possible impact on heavy metals contamination in the study area. The Pearson correlation analysis showed significant correlations (p < 0.01 and p < 0.05) between most of the metals in the samples of effluents, water, sediments, and fish muscles. The percentage enrichment factor (EF%) and geo-accumulation index () were followed to evaluate metal contamination in the sediment samples. Dhalaibeel sediment was maximally enriched for Cr (53.55%) and Bangshi River sediment for Zn (54.37%). The geo-accumulation index values for the sediment samples were less than zero, indicating that the sediment samples were free from contamination. This study could be used as a model study to assess the impact of anthropogenic activities on heavy metals contamination in aquatic ecosystems. Keywords: Heavy metal contaminationeffluentswatersedimentfishexport processing zone Acknowledgement The authors thank the authority of Bangladesh Atomic Energy Commission (BAEC) for providing laboratory facilities to analyze effluent, water, and fish samples using a conventional technique. The authors are also especially grateful to M.A. Mannaf, senior technical officer, BAEC, for digesting the fish samples for metal analysis. The authors are also delighted to express their gratefulness and sincerest thanks to Professor Jasim Uddin Ahmad (Ex Vice Chancellor, JU), Department of Chemistry, Jahangirnagar University (JU), Savar, Dhaka, for his valuable suggestions and cooperation in carrying out this research.
Abstract A laboratory-scale study was undertaken to evaluate the liquid state bioconversion (LSB) in terms of biodegradation of microbially treated domestic wastewater sludge (biosolids) as well as its kinetics. The potential fungal strains and process factors developed from previous studies were used throughout the study. The results presented in this study showed that an effective biodegradation occurred with the biosolids (sludge cake) accumulated. The maximum biosolids (sludge cake) accumulated (93.8 g/kg of liquid sludge) enriched with the biomass protein (30.2 g/kg of dry biosolids), was achieved which improved the effluent quality by enhancing the removal of chemical oxygen demand (COD), reducing sugar (RS), soluble protein (SP), total dissolved solids (TDS), and total suspended solids (TSS). The higher reduction of specific resistance to filtration (SRF) was observed during bioconversion process. The kinetics results showed that the experimental data were better fitted for the biodegradation efficiency, and biosolids accumulation and biodegradation rate.
Effects of Trichoderma-enriched biofertilizer such as biofertilizer/compost [BioF/compost (household/kitchen wastes composted with Trichoderma harzianum T22)] and biofertilizer/liquid [BioF/liquid (T. harzianum T22 broth culture contains spores and mycelia)] alone or in combination with NPK fertilizer were evaluated for the growth, dry matter production, yield and yield attributes of mustard (Brassica campestris) grown under field condition. BioF/compost performed better than that of BioF/liquid. Recommended doses of NPK and 50% BioF/compost + 50% NPK showed similar effects on growth, dry matter accumulation and yield of mustard. Seed yield per plant was increased by 5.34% over the recommended dose of NPK, when the crop was fertilized with 50% BioF/compost along with 50% NPK. However, seed yield per plant was decreased only by 7.3 and 6.6% when BioF/compost, and 75% BioF/compost + 25% NPK were applied as compared to the recommended dose of NPK. Since 20% reduced yield is accepted in organic faming worldwide, the treatments namely BioF/compost, 50% BioF/compost + 50% NPK and 75% BioF/compost + 25% NPK might be recommended for mustard cultivation in Bangladesh, which may reduce cultivation cost and also reduce environmental pollution. Keywords: Mustard; growth; dry matter production; seed yield; biofertilizer DOI: 10.3329/agric.v8i2.7579 The Agriculturists 8(2): 66-73 (2010)
An attempt was made to study genotypic variance, phenotypic variance, environmental variance, genotypic coefficient of variation (GCV), phenotypic coefficient of variation (PCV), heritability (h2b) and genetic advance (GA) for some rice genotypes during July 2007 to January 2009 at BSMRAU campus, Gazipur 1706. Significant variations were obtained among the genotypes for all the characters studied. Considering genetic parameters high genotypic coefficient of variation (GCV) value was observed for harvest index followed by yield per hill, number of tillers per hill, number of filled grain per panicle, whereas days to maturity showed very low GCV. High heritability with high genetic advance (GA) observed for yield per hill followed by number of tillers per hill, number of filled grains per panicle indicated that these characters were under additive gene control and selection for genetic improvement for these traits might be effective.DOI: http://dx.doi.org/10.3329/bjpbg.v24i2.17004
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