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Papers by KHANDAKAR IFTEKHARUDDAULA

Cereal Grains - Volume 2, 2021

Agricultural land and resources reduced annually because of climate change thus it is necessary t... more Agricultural land and resources reduced annually because of climate change thus it is necessary to further increase the productivity of the major staple food rice to sustain food security worldwide. However, rice productivity enhancement is one of the key challenges in abiotic stress-prone environments. The integration of cutting-edge breeding approaches and research management methods in the current varietal improvement pipelines can make a step-change towards varietal improvement for the abiotic stress-prone environments. Proper implementation of breeder’s equations in the crop improvement pipeline can deliver a higher rate of genetic gain. Single Seed Descent based Rapid Generation Advance (RGA) technique in field and greenhouse is the most promising innovations and low-cost, high-throughput marker-assisted selection approaches are applied for rapid and efficient selection for abiotic stress-tolerances. Also improving efficiency, intensity, and accuracy of selection and reducing ...

Frontiers in Plant Science, 2019

With the changing climatic conditions and reducing labor-water availability, the potential contri... more With the changing climatic conditions and reducing labor-water availability, the potential contribution of aerobic rice varieties and cultivation system to develop a sustainable rice based agri-food system has never been more important than today. Keeping in mind the goal of identifying high-yielding aerobic rice varieties for wider adaptation, a set of aerobic rice breeding lines were developed and evaluated for grain yield, plant height, and days to 50% flowering in 23 experiments conducted across different location in Philippines, India, Bangladesh, Nepal, and Lao-PDR between 2014 and 2017 in both wet and dry seasons. The heritability for grain yield ranged from 0.52 to 0.90. The season-wise two-stage analysis indicated significant genotype x location interaction for yield under aerobic conditions in both wet and dry seasons. The genotype × season × location interaction for yield was non-significant in both seasons indicating that across seasons the genotypes at each location did not show variability in the grain yield performance. Mean grain yield of the studied genotypes across different locations/seasons ranged from 2,085 to 6,433 Kg ha −1. The best-fit model for yield stability with low AIC value (542.6) was AMMI(1) model. The identified stable genotypes;

Plant Production Science, 2017

Rice production needs to increase in the future in order to meet increasing demands. The developm... more Rice production needs to increase in the future in order to meet increasing demands. The development of new improved and higher yielding varieties more quickly will be needed to meet this demand. However, most rice breeding programmes in the world have not changed in several decades. In this article, we revisit the evidence in favour of using rapid generation advance (RGA) as a routine breeding method. We describe preliminary activities at the International Rice Research Institute (IRRI) to re-establish RGA on a large scale as the main breeding method for irrigated rice breeding. We also describe experiences from the early adoption at the Bangladesh Rice Research Institute. Evaluation of RGA breeding lines at IRRI for yield, flowering time and plant height indicated transgressive segregation for all traits. Some RGA lines were also higher yielding than the check varieties. The cost advantages of using RGA compared to the pedigree method were also empirically determined by performing an economic analysis. This indicated that RGA is several times more cost effective and advantages will be realized after 1 year even if facilities need to be built. Based on our experience, and previous independent research empirically testing the RGA method in rice, we recommend that this method should be implemented for routine rice breeding in order to improve breeding efficiency.

Scientific reports, Jan 18, 2018

Flooding is one of the major constraints for rice production in rainfed lowlands, especially in y... more Flooding is one of the major constraints for rice production in rainfed lowlands, especially in years and areas of high rainfall. Incorporating the Sub1 (Submergence1) gene into high yielding popular varieties has proven to be the most feasible approach to sustain rice production in submergence-prone areas. Introgression of this QTL into popular varieties has resulted in considerable improvement in yield after flooding. However, its impact under non-flooded conditions or years have not been thoroughly evaluated which is important for the farmers to accept and adopt any new version of their popular varieties. The present study was carried out to evaluate the effect of Sub1 on grain yield of rice in different genetic backgrounds, under non-submergence conditions, over years and locations. The study was carried out using head to head trials in farmer's fields, which enable the farmers to more accurately compare the performance of Sub1 varieties with their recurrent parents under ow...

Frontiers in plant science, 2017

Reducing water requirements and lowering environmental footprints require attention to minimize r... more Reducing water requirements and lowering environmental footprints require attention to minimize risks to food security. The present study was conducted with the aim to identify appropriate root traits enhancing rice grain yield under alternate wetting and drying conditions (AWD) and identify stable, high-yielding genotypes better suited to the AWD across variable ecosystems. Advanced breeding lines, popular rice varieties and drought-tolerant lines were evaluated in a series of 23 experiments conducted in the Philippines, India, Bangladesh, Nepal and Cambodia in 2015 and 2016. A large variation in grain yield under AWD conditions enabled the selection of high-yielding and stable genotypes across locations, seasons and years. Water savings of 5.7-23.4% were achieved without significant yield penalty across different ecosystems. The mean grain yield of genotypes across locations ranged from 3.5 to 5.6 t/ha and the mean environment grain yields ranged from 3.7 (Cambodia) to 6.6 (India)...

Bangladesh Journal of Plant Breeding and Genetics, 2008

Hayman’s analysis of variance (ANOVA) indicated importance of both additive and non-additive gene... more Hayman’s analysis of variance (ANOVA) indicated importance of both additive and non-additive genetic components for all the grain characters. The ANOVA showed unidirectional dominance for the characters viz. kernel breadth, upper empty glume length and endosperm-embryo ratio, asymmetrical gene distribution for the characters viz. grain length, grain breadth, kernel length, kernel breadth and kernel thickness and residual dominance effects for all the grain characters studied. Five out of nine grain characters viz. grain breadth, grain thickness, kernel breadth, kernel thickness and upper empty glume length followed the simple additive-dominance genetic model. The rest of the grain characters showed nonallelic gene interaction or epistasis. According to Vr-Wr graph, partial dominance was involved in the action of genes governing the inheritance of grain breadth, grain thickness, kernel breadth and kernel thickness while complete dominance was involved in the inheritance of upper empt...

Field Crops Research, 2016

Flash flooding imparts adverse effect on rice production worldwide. Because of the needs for mult... more Flash flooding imparts adverse effect on rice production worldwide. Because of the needs for multiple cropping and to avoid incidences of cold and diseases later in the season, early maturing submergence tolerant varieties have been urgently needed in some rice producing areas. Markerassisted backcrossing (MABC) was used to introgress the submergence-tolerance SUB1 QTL from BRRI dhan52 into a short-duration rice variety, BRRI dhan33. In this particular study, a combination of foreground and phenotypic selection was performed during the BC 1 F 1-BC 4 F 1 stages, while the whole set of foreground, recombinant and background markers were used at the BC 4 F 2 stage. At the final stage, the recovery of recipient parent genome ranged from 90.7 to 95.2% in 15 BC 4 F 3 promising lines. The introgression sizes of the different Sub1 lines were estimated to be around 2.4 to 5.6 Mb. The submergence tolerance of line BR9157-12-2-37-13-15-40 was found to be the best, having 87.7% survival. The grain yield of the Sub1 lines was also significantly higher compared with that of the original variety, BRRI dhan33, under both flooded and non-flooded conditions in on-station and on-farm trials. The maximum grain yield obtained from a BRRI dhan33-Sub1 line was 4.8 t/ha under on-farm non-flooded conditions and 3.8 t/ha under on-farm flooded conditions. The best selected Sub1 line may be released in the future as a short-duration, submergence-tolerant high-yielding variety for flood-prone rainfed areas in Bangladesh.

Rice Science, 2016

Eighteen isolates of Rhizoctonia solani collected from infected rice plants in four different loc... more Eighteen isolates of Rhizoctonia solani collected from infected rice plants in four different locations of Bangladesh were studied by using morphological characters and molecular markers. Anastomosis study with a reference isolate confirmed that all the isolates belonged to R. solani. Significant variation was observed in sclerotial size, shape and distribution. Un-weighted pair group method with arithmetic mean dendrogram constructed based on the Gower's general similarity coefficient showed that these isolates were grouped into four clusters at the 0.68 similarity coefficent according to morphological characters. Cluster I was a major cluster consisting of 13 isolates, while clusters II to IV consisted of 1 or 2 isolates. Analyses by variable number of tandem repeat and amplified fragment length polymorphism markers showed that the isolates were grouped into five and three clusters at a similarity coefficient of 0.64 and 0.69, respectively. Although most of the variability was found between isolates from different regions as expected, significant variation was observed within the isolates collected from similar agro-ecological regions. Our results suggest the presence of different races of R. solani within the same local geographic regions.

In future, enough water will not be available to irrigate the entire area for boro cultivation. A... more In future, enough water will not be available to irrigate the entire area for boro cultivation. As a resource saving option, Aus and Aman based cropping pattern appears to be quite prospective. Around 20% areas of Boro rice (around 0.9 Mha) can be shifted to Aus rice areas. In order to compensate the reduced amount of Boro production, the cumulative Aus areas should be increased to 1.8 Mha and the total production of Aus will have to be 5.2 million metric ton. To harvest this production, grain yield of modern Aus at farmers' field should be around 4.0 ton/ha for which, in addition to other technologies, needs the assurance of partial or supplemental irrigation facilities. Moreover, location-specific varieties along with production technologies will be the crucial factors for attaining the goal. For the timely establishment and post-harvest operations, particularly for Aus rice, farm mechanization needs to be emphasized. Some fallow areas in South and North-eastern region should ...

Rice Science, 2015

Submergence tolerant high yielding rice variety was developed using BR11 as a recipient parent ap... more Submergence tolerant high yielding rice variety was developed using BR11 as a recipient parent applying foreground, phenotypic and background selection approaches. Recombinant selection was found essential to minimize linkage drag by BC 2 F 2 generation. Without recombinant selection, the introgression size in the backcross recombinant lines (BRLs) was approximately 15 Mb on the carrier chromosome. The BRLs were found submergence tolerance compared to the check varieties under complete submergence for two weeks at Bangladesh Rice Research Institute, and produced higher yield compared to the isogenic Sub1-line under controlled submerged condition. The BRL IR85260-66-654-Gaz2 was released as BRRI dhan52 in 2010, which was the first high yielding submergence tolerant variety in Bangladesh. BRRI dhan52 produced grain yield ranging from 4.2 to 5.2 t/hm 2 under different flash flood prone areas of Bangladesh in three consecutive seasons. The study demonstrated the efficiency of recombinant selection and better adaptability of the newly released submergence tolerant high yielding variety in flash flood prone different areas of the country with respect to submergence tolerance and yield potential.

Pakistan Journal of Biological Sciences, 2004

Bangladesh Journal of Plant Breeding and Genetics, 2013

Forty advanced breeding lines of rice were studied during T Aman season (rainfed ecosystem) for f... more Forty advanced breeding lines of rice were studied during T Aman season (rainfed ecosystem) for finding out selection indices, variability and character association for grain yield and its components. All the tested characters were found showing significant variation. The highest genotypic, environmental and phenotypic variances were found in filled grains/panicle followed by plant height. High heritability associated with high genetic advance were obtained in panicles/hill, plant height, filled grains/panicle, 1000-grain weight and grain yield. Genotypic correlation coefficients were higher than the corresponding phenotypic correlation coefficients in most of the cases. Panicle length, panicles/hill and filled grains/panicle showed significant positive correlation with grain yield. Path analysis revealed that filled grains/panicle, panicles/hill and 1000-grain weight had positive and highest direct effects on grain yield. Moreover, panicle length had highest indirect effect on grai...

Journal of Biological Sciences, 2002

Journal of Biological Sciences, 2003

Pakistan Journal of Biological Sciences, 2001

Journal of Biological Sciences, 2002

Bangladesh Journal of Agricultural Research, 1970

An experiment was carried out to study the genetic components for eight panicle characters in ric... more An experiment was carried out to study the genetic components for eight panicle characters in rice using an 8-parent half diallel cross excluding reciprocals during Transplant Aman season, 2003. The parental genotypes used in the study were BRRI dhan29, BR4828-54-4-l-4-9, BRR1 dhan28, 1R8, Amol3, 1R65610-38-2-4-2-6-3, Minikit and ZhongYu7, which were chosen for their diversity in panicle characters. Hayman's analysis of variance (ANOVA) indicated importance of both additive and non-additive genetic components for all the panicle characters except dominance component for filled grains/secondary branches. The ANOVA showed unidirectional dominance for the characters viz, primary branch length, secondary branch length, primary branches/panicle, secondary branches/panicle and filled grains/primary branch, asymmetrical gene distribution for all the panicle traits except filled grains/secondary branch and residual dominance effects for all the panicle characters studied. Two out of eig...

Breeding Science, 2012

Marker assisted backcrossing has been used effectively to transfer the submergence tolerance gene... more Marker assisted backcrossing has been used effectively to transfer the submergence tolerance gene SUB1 into popular rice varieties, but the approach can be costly. The selection strategy comprising foreground marker and phenotypic selection was investigated as an alternative. The non-significant correlation coefficients between ranking of phenotypic selection and ranking of background marker selection in BC 2 F 1 , BC 3 F 1 and BC 3 F 2 generations indicated inefficiency of phenotypic selection compared to marker-assisted background selection with respect to recovery of the recipient genome. In addition, the introgression size of the chromosome fragment containing SUB1 was approximately 17 Mb, showing the effects of linkage drag. The significant correlation coefficient between rankings of phenotypic selection with the percentage of recipient alleles in the BC 1 F 1 generation suggested that background selection could be avoided in this generation to minimize the genotyping cost. The phenotypically selected best plant of the BC 3 F 1 generation was selfed and backcross recombinant lines were selected in the resulting BC 3 F 4 generation. The selection strategy could be appropriate for the introgression of SUB1 QTL in countries that lack access to high-throughput genotyping facilities.

Genetic Resources and Crop Evolution, 2015

ABSTRACT A total of 300 germplasm accessions collected from submergence-prone areas of Bangladesh... more ABSTRACT A total of 300 germplasm accessions collected from submergence-prone areas of Bangladesh were selected from the genebank of the Bangladesh Rice Research Institute (BRRI) for an allelic diversity study on submergence tolerance during the vegetative stage. Through screening under controlled submergence for three consecutive years, eight accessions were selected for having submergence tolerance with survival ranging from 71.2 to 95.4 %. A total of 20 SUB1-region SSR and Indel markers, spanning from 4.5 to 8.6 Mb on chromosome 9, were used to study the allelic diversity of 16 selected rice accessions, including the eight submergence tolerant accessions and eight sensitive and tolerant checks. A total of 58 alleles were detected at the loci of the 20 markers across the 16 rice accessions. The number of alleles per locus ranged from two to five, with an average of 2.90 alleles across the 20 loci. Genetic similarity analysis using the unweighted pairgroup method using arithmetic mean (UPGMA) clustering system generated two major genetic clusters, each of them with three subgroups. DG1-349, Kalojoma, DSL-78-8, Damsi and Putidepa were identified as having higher submergence tolerance but not possessing the same resistance allele as FR13A. Furthermore, RT-PCR analysis of SUB1A, the gene underlying the SUB1 QTL, showed that the transcript abundance in these accessions was significantly less than that of FR13A. Thus, these accessions were selected as potential genetic donors for identifying novel submergence-tolerance QTLs.

Cereal Grains - Volume 2, 2021

Agricultural land and resources reduced annually because of climate change thus it is necessary t... more Agricultural land and resources reduced annually because of climate change thus it is necessary to further increase the productivity of the major staple food rice to sustain food security worldwide. However, rice productivity enhancement is one of the key challenges in abiotic stress-prone environments. The integration of cutting-edge breeding approaches and research management methods in the current varietal improvement pipelines can make a step-change towards varietal improvement for the abiotic stress-prone environments. Proper implementation of breeder’s equations in the crop improvement pipeline can deliver a higher rate of genetic gain. Single Seed Descent based Rapid Generation Advance (RGA) technique in field and greenhouse is the most promising innovations and low-cost, high-throughput marker-assisted selection approaches are applied for rapid and efficient selection for abiotic stress-tolerances. Also improving efficiency, intensity, and accuracy of selection and reducing ...

Frontiers in Plant Science, 2019

With the changing climatic conditions and reducing labor-water availability, the potential contri... more With the changing climatic conditions and reducing labor-water availability, the potential contribution of aerobic rice varieties and cultivation system to develop a sustainable rice based agri-food system has never been more important than today. Keeping in mind the goal of identifying high-yielding aerobic rice varieties for wider adaptation, a set of aerobic rice breeding lines were developed and evaluated for grain yield, plant height, and days to 50% flowering in 23 experiments conducted across different location in Philippines, India, Bangladesh, Nepal, and Lao-PDR between 2014 and 2017 in both wet and dry seasons. The heritability for grain yield ranged from 0.52 to 0.90. The season-wise two-stage analysis indicated significant genotype x location interaction for yield under aerobic conditions in both wet and dry seasons. The genotype × season × location interaction for yield was non-significant in both seasons indicating that across seasons the genotypes at each location did not show variability in the grain yield performance. Mean grain yield of the studied genotypes across different locations/seasons ranged from 2,085 to 6,433 Kg ha −1. The best-fit model for yield stability with low AIC value (542.6) was AMMI(1) model. The identified stable genotypes;

Plant Production Science, 2017

Rice production needs to increase in the future in order to meet increasing demands. The developm... more Rice production needs to increase in the future in order to meet increasing demands. The development of new improved and higher yielding varieties more quickly will be needed to meet this demand. However, most rice breeding programmes in the world have not changed in several decades. In this article, we revisit the evidence in favour of using rapid generation advance (RGA) as a routine breeding method. We describe preliminary activities at the International Rice Research Institute (IRRI) to re-establish RGA on a large scale as the main breeding method for irrigated rice breeding. We also describe experiences from the early adoption at the Bangladesh Rice Research Institute. Evaluation of RGA breeding lines at IRRI for yield, flowering time and plant height indicated transgressive segregation for all traits. Some RGA lines were also higher yielding than the check varieties. The cost advantages of using RGA compared to the pedigree method were also empirically determined by performing an economic analysis. This indicated that RGA is several times more cost effective and advantages will be realized after 1 year even if facilities need to be built. Based on our experience, and previous independent research empirically testing the RGA method in rice, we recommend that this method should be implemented for routine rice breeding in order to improve breeding efficiency.

Scientific reports, Jan 18, 2018

Flooding is one of the major constraints for rice production in rainfed lowlands, especially in y... more Flooding is one of the major constraints for rice production in rainfed lowlands, especially in years and areas of high rainfall. Incorporating the Sub1 (Submergence1) gene into high yielding popular varieties has proven to be the most feasible approach to sustain rice production in submergence-prone areas. Introgression of this QTL into popular varieties has resulted in considerable improvement in yield after flooding. However, its impact under non-flooded conditions or years have not been thoroughly evaluated which is important for the farmers to accept and adopt any new version of their popular varieties. The present study was carried out to evaluate the effect of Sub1 on grain yield of rice in different genetic backgrounds, under non-submergence conditions, over years and locations. The study was carried out using head to head trials in farmer's fields, which enable the farmers to more accurately compare the performance of Sub1 varieties with their recurrent parents under ow...

Frontiers in plant science, 2017

Reducing water requirements and lowering environmental footprints require attention to minimize r... more Reducing water requirements and lowering environmental footprints require attention to minimize risks to food security. The present study was conducted with the aim to identify appropriate root traits enhancing rice grain yield under alternate wetting and drying conditions (AWD) and identify stable, high-yielding genotypes better suited to the AWD across variable ecosystems. Advanced breeding lines, popular rice varieties and drought-tolerant lines were evaluated in a series of 23 experiments conducted in the Philippines, India, Bangladesh, Nepal and Cambodia in 2015 and 2016. A large variation in grain yield under AWD conditions enabled the selection of high-yielding and stable genotypes across locations, seasons and years. Water savings of 5.7-23.4% were achieved without significant yield penalty across different ecosystems. The mean grain yield of genotypes across locations ranged from 3.5 to 5.6 t/ha and the mean environment grain yields ranged from 3.7 (Cambodia) to 6.6 (India)...

Bangladesh Journal of Plant Breeding and Genetics, 2008

Hayman’s analysis of variance (ANOVA) indicated importance of both additive and non-additive gene... more Hayman’s analysis of variance (ANOVA) indicated importance of both additive and non-additive genetic components for all the grain characters. The ANOVA showed unidirectional dominance for the characters viz. kernel breadth, upper empty glume length and endosperm-embryo ratio, asymmetrical gene distribution for the characters viz. grain length, grain breadth, kernel length, kernel breadth and kernel thickness and residual dominance effects for all the grain characters studied. Five out of nine grain characters viz. grain breadth, grain thickness, kernel breadth, kernel thickness and upper empty glume length followed the simple additive-dominance genetic model. The rest of the grain characters showed nonallelic gene interaction or epistasis. According to Vr-Wr graph, partial dominance was involved in the action of genes governing the inheritance of grain breadth, grain thickness, kernel breadth and kernel thickness while complete dominance was involved in the inheritance of upper empt...

Field Crops Research, 2016

Flash flooding imparts adverse effect on rice production worldwide. Because of the needs for mult... more Flash flooding imparts adverse effect on rice production worldwide. Because of the needs for multiple cropping and to avoid incidences of cold and diseases later in the season, early maturing submergence tolerant varieties have been urgently needed in some rice producing areas. Markerassisted backcrossing (MABC) was used to introgress the submergence-tolerance SUB1 QTL from BRRI dhan52 into a short-duration rice variety, BRRI dhan33. In this particular study, a combination of foreground and phenotypic selection was performed during the BC 1 F 1-BC 4 F 1 stages, while the whole set of foreground, recombinant and background markers were used at the BC 4 F 2 stage. At the final stage, the recovery of recipient parent genome ranged from 90.7 to 95.2% in 15 BC 4 F 3 promising lines. The introgression sizes of the different Sub1 lines were estimated to be around 2.4 to 5.6 Mb. The submergence tolerance of line BR9157-12-2-37-13-15-40 was found to be the best, having 87.7% survival. The grain yield of the Sub1 lines was also significantly higher compared with that of the original variety, BRRI dhan33, under both flooded and non-flooded conditions in on-station and on-farm trials. The maximum grain yield obtained from a BRRI dhan33-Sub1 line was 4.8 t/ha under on-farm non-flooded conditions and 3.8 t/ha under on-farm flooded conditions. The best selected Sub1 line may be released in the future as a short-duration, submergence-tolerant high-yielding variety for flood-prone rainfed areas in Bangladesh.

Rice Science, 2016

Eighteen isolates of Rhizoctonia solani collected from infected rice plants in four different loc... more Eighteen isolates of Rhizoctonia solani collected from infected rice plants in four different locations of Bangladesh were studied by using morphological characters and molecular markers. Anastomosis study with a reference isolate confirmed that all the isolates belonged to R. solani. Significant variation was observed in sclerotial size, shape and distribution. Un-weighted pair group method with arithmetic mean dendrogram constructed based on the Gower's general similarity coefficient showed that these isolates were grouped into four clusters at the 0.68 similarity coefficent according to morphological characters. Cluster I was a major cluster consisting of 13 isolates, while clusters II to IV consisted of 1 or 2 isolates. Analyses by variable number of tandem repeat and amplified fragment length polymorphism markers showed that the isolates were grouped into five and three clusters at a similarity coefficient of 0.64 and 0.69, respectively. Although most of the variability was found between isolates from different regions as expected, significant variation was observed within the isolates collected from similar agro-ecological regions. Our results suggest the presence of different races of R. solani within the same local geographic regions.

In future, enough water will not be available to irrigate the entire area for boro cultivation. A... more In future, enough water will not be available to irrigate the entire area for boro cultivation. As a resource saving option, Aus and Aman based cropping pattern appears to be quite prospective. Around 20% areas of Boro rice (around 0.9 Mha) can be shifted to Aus rice areas. In order to compensate the reduced amount of Boro production, the cumulative Aus areas should be increased to 1.8 Mha and the total production of Aus will have to be 5.2 million metric ton. To harvest this production, grain yield of modern Aus at farmers' field should be around 4.0 ton/ha for which, in addition to other technologies, needs the assurance of partial or supplemental irrigation facilities. Moreover, location-specific varieties along with production technologies will be the crucial factors for attaining the goal. For the timely establishment and post-harvest operations, particularly for Aus rice, farm mechanization needs to be emphasized. Some fallow areas in South and North-eastern region should ...

Rice Science, 2015

Submergence tolerant high yielding rice variety was developed using BR11 as a recipient parent ap... more Submergence tolerant high yielding rice variety was developed using BR11 as a recipient parent applying foreground, phenotypic and background selection approaches. Recombinant selection was found essential to minimize linkage drag by BC 2 F 2 generation. Without recombinant selection, the introgression size in the backcross recombinant lines (BRLs) was approximately 15 Mb on the carrier chromosome. The BRLs were found submergence tolerance compared to the check varieties under complete submergence for two weeks at Bangladesh Rice Research Institute, and produced higher yield compared to the isogenic Sub1-line under controlled submerged condition. The BRL IR85260-66-654-Gaz2 was released as BRRI dhan52 in 2010, which was the first high yielding submergence tolerant variety in Bangladesh. BRRI dhan52 produced grain yield ranging from 4.2 to 5.2 t/hm 2 under different flash flood prone areas of Bangladesh in three consecutive seasons. The study demonstrated the efficiency of recombinant selection and better adaptability of the newly released submergence tolerant high yielding variety in flash flood prone different areas of the country with respect to submergence tolerance and yield potential.

Pakistan Journal of Biological Sciences, 2004

Bangladesh Journal of Plant Breeding and Genetics, 2013

Forty advanced breeding lines of rice were studied during T Aman season (rainfed ecosystem) for f... more Forty advanced breeding lines of rice were studied during T Aman season (rainfed ecosystem) for finding out selection indices, variability and character association for grain yield and its components. All the tested characters were found showing significant variation. The highest genotypic, environmental and phenotypic variances were found in filled grains/panicle followed by plant height. High heritability associated with high genetic advance were obtained in panicles/hill, plant height, filled grains/panicle, 1000-grain weight and grain yield. Genotypic correlation coefficients were higher than the corresponding phenotypic correlation coefficients in most of the cases. Panicle length, panicles/hill and filled grains/panicle showed significant positive correlation with grain yield. Path analysis revealed that filled grains/panicle, panicles/hill and 1000-grain weight had positive and highest direct effects on grain yield. Moreover, panicle length had highest indirect effect on grai...

Journal of Biological Sciences, 2002

Journal of Biological Sciences, 2003

Pakistan Journal of Biological Sciences, 2001

Journal of Biological Sciences, 2002

Bangladesh Journal of Agricultural Research, 1970

An experiment was carried out to study the genetic components for eight panicle characters in ric... more An experiment was carried out to study the genetic components for eight panicle characters in rice using an 8-parent half diallel cross excluding reciprocals during Transplant Aman season, 2003. The parental genotypes used in the study were BRRI dhan29, BR4828-54-4-l-4-9, BRR1 dhan28, 1R8, Amol3, 1R65610-38-2-4-2-6-3, Minikit and ZhongYu7, which were chosen for their diversity in panicle characters. Hayman's analysis of variance (ANOVA) indicated importance of both additive and non-additive genetic components for all the panicle characters except dominance component for filled grains/secondary branches. The ANOVA showed unidirectional dominance for the characters viz, primary branch length, secondary branch length, primary branches/panicle, secondary branches/panicle and filled grains/primary branch, asymmetrical gene distribution for all the panicle traits except filled grains/secondary branch and residual dominance effects for all the panicle characters studied. Two out of eig...

Breeding Science, 2012

Marker assisted backcrossing has been used effectively to transfer the submergence tolerance gene... more Marker assisted backcrossing has been used effectively to transfer the submergence tolerance gene SUB1 into popular rice varieties, but the approach can be costly. The selection strategy comprising foreground marker and phenotypic selection was investigated as an alternative. The non-significant correlation coefficients between ranking of phenotypic selection and ranking of background marker selection in BC 2 F 1 , BC 3 F 1 and BC 3 F 2 generations indicated inefficiency of phenotypic selection compared to marker-assisted background selection with respect to recovery of the recipient genome. In addition, the introgression size of the chromosome fragment containing SUB1 was approximately 17 Mb, showing the effects of linkage drag. The significant correlation coefficient between rankings of phenotypic selection with the percentage of recipient alleles in the BC 1 F 1 generation suggested that background selection could be avoided in this generation to minimize the genotyping cost. The phenotypically selected best plant of the BC 3 F 1 generation was selfed and backcross recombinant lines were selected in the resulting BC 3 F 4 generation. The selection strategy could be appropriate for the introgression of SUB1 QTL in countries that lack access to high-throughput genotyping facilities.

Genetic Resources and Crop Evolution, 2015

ABSTRACT A total of 300 germplasm accessions collected from submergence-prone areas of Bangladesh... more ABSTRACT A total of 300 germplasm accessions collected from submergence-prone areas of Bangladesh were selected from the genebank of the Bangladesh Rice Research Institute (BRRI) for an allelic diversity study on submergence tolerance during the vegetative stage. Through screening under controlled submergence for three consecutive years, eight accessions were selected for having submergence tolerance with survival ranging from 71.2 to 95.4 %. A total of 20 SUB1-region SSR and Indel markers, spanning from 4.5 to 8.6 Mb on chromosome 9, were used to study the allelic diversity of 16 selected rice accessions, including the eight submergence tolerant accessions and eight sensitive and tolerant checks. A total of 58 alleles were detected at the loci of the 20 markers across the 16 rice accessions. The number of alleles per locus ranged from two to five, with an average of 2.90 alleles across the 20 loci. Genetic similarity analysis using the unweighted pairgroup method using arithmetic mean (UPGMA) clustering system generated two major genetic clusters, each of them with three subgroups. DG1-349, Kalojoma, DSL-78-8, Damsi and Putidepa were identified as having higher submergence tolerance but not possessing the same resistance allele as FR13A. Furthermore, RT-PCR analysis of SUB1A, the gene underlying the SUB1 QTL, showed that the transcript abundance in these accessions was significantly less than that of FR13A. Thus, these accessions were selected as potential genetic donors for identifying novel submergence-tolerance QTLs.