BRRI Dhan29 Research Articles

Genetic evaluation of boro rice (Oryza sativa L.) genotypes under irrigated and rainfed conditions

Drought is a major abiotic constraint for growing rainfed rice in Bangladesh. A set of 18 boro rice genotypes were evaluated under irrigated and rainfed conditions to identify the high yielding and stress tolerant genotypes. The experiment was conducted by using randomized complete block design with three replications. Significant variations were observed among the genotypes both in irrigated and rainfed conditions. The genotypes BRRI dhan55, Gopal Deshi and Soilerpona showed the superior performance in terms of grain yield and yield contributing characters under rainfed condition. Based on stress tolerance index (STI) value, the genotypes BRRI dhan55, BRRI dhan58, Soilerpuna and Gopaldeshi were graded as drought tolerant genotypes. Under rainfed condition, yield per plant showed the positive and significant correlation with flag leaf length, number of primary branches per panicle, number of secondary branches per panicle, number of grains per panicle and thousand-seed weight. Path analysis revealed that the number of primary/secondary branches per panicle, and number of unfilled grains per panicle showed the highest positive and direct effect on grain yield under irrigated condition while Plant height, panicle length and thousand-seed weight had the highest direct but negative effect on grain yield.Thousand seed weight, number of primary branches per panicle and number of unfilled grains per panicle showed the highest positive and direct effect on grain yield under rainfed condition. Based on the results, seven genotypes from among the eighteen tested namely BRRI dhan36, BRRI dhan55, BRRI dhan58, BRRI dhan59, Soilerpona, Gopal Deshi and Borail were identified as drought tolerance genotypes with high yield potential. Bangladesh J. Agri. 2019-2021, 44-46: 77-87

Nitrogen management in boro rice using chlorophyll meter (SPAD) under sub-tropical condition

Nitrogen deficiency in rice has so far received limited attention in Bangladesh. Balanced fertilization is a pre-requisite for better rice production and it is necessary to determine optimum combination of fertilizer dose and varieties. The field experiment was carried out during the period from November 2020 to May 2021 at the Agronomy Field Laboratory, Bangladesh Agricultural University (BAU), Mymensingh to study the SPAD value and yield performance of boro rice varieties at different nitrogen levels. The experiment comprised of four boro rice varieties viz., BRRI dhan28, BRRI dhan58, BRRI dhan74, BRRI dhan81 and four level of nitrogenous fertilizers viz. 50 kg N ha-1, 100 kg N ha-1, 150 kg N ha-1 and 200kg N ha-1. The experiment was laid out in a randomized complete block design with three replications. SPAD value ranged from 34.01 to 42.12 for variety and 37.81 to 42.15 for nitrogen application, while leaf nitrogen ranged from 2.98 to 3.67 % for variety and 2.94 to 3.48%. The yield contributing parameter varied significantly with variety and nitrogen rate. The highest grain yield (6.13 t ha-1) was found in BRRI dhan58 and the lowest (3.89 t ha-1) was observed in BRRI dhan28. In terms of fertilizer management, the highest grain yield (5.35 t ha-1) was obtained due to the application of 150 kg N ha-1 and the lowest grain yield (4.72 t ha-1) was recorded from50 kg N ha-1. The interactive effect of variety and fertilizer application exerted that the yield of BRRI dhan58 with 150 kg N ha-1 was the highest (6.59 tha-1) and the lowest performance (3.42 tha-1) in grain yield was found in BRRI dhan28 with 50 kg N ha-1. Thus, the variety BRRI dhan58 with 150 kg N ha-1 was superior for attaining the highest yield.

Genetic Mapping to Detect Stringent QTLs Using 1k-RiCA SNP Genotyping Platform from the New Landrace Associated with Salt Tolerance at the Seedling Stage in Rice

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.

Adoption Trend of Climate-Resilient Rice Varieties in Bangladesh

Rice is a major crop in Bangladesh that supports both food security and livelihoods. However, a need remains for improved productivity and adaptation to the risks associated with climate change. To accomplish this, the increased adoption of climate-resilient and high-yielding rice varieties can be beneficial. Therefore, we conducted a study in Bangladesh over three consecutive years: 2016, 2017, and 2018. The scope of the study included the major cropping season (wet), Aman. The yield advantages of climate-resilient rice varieties were evaluated and compared with those of the varieties popular with farmers. We included new stress-tolerant varieties, such as submergence-tolerant rice (BRRI dhan51 and BRRI dhan52) and drought-tolerant rice (BRRI dhan56 and BRRI dhan71), along with farmer-chosen controls, in the study. We conducted the evaluation through on-farm trials to compare the varieties in both submergence- and drought-affected environments. The seasonal trials provided measured results of yield advantages. The participating farmers were also studied over the three-year-period to capture their varietal adoption rates. We calculated both the location estimated yield advantages (LEYA) and the location observed yield advantages (LOYA). The results revealed that, under non-stress conditions, the grain yields of climate-resilient varieties were either statistically similar to or higher than those of the farmer-chosen controls. Our study also revealed a year-to-year progressive adoption rate for the introduced varieties. The study suggests that the wide-scale introduction and popularization of climate-resilient varieties can ensure higher productivity and climate risk adaptation. The close similarity between LOYA and LEYA indicated that the observational and experiential conclusions of the host farmers were similar to the scientific performance of the varieties. We also found that comparison performed through on-farm trials was a critical method for enhancing experiential learning and obtaining an accurate estimation of yield advantages.

Phenotypic and Molecular Characterization of Rice Genotypes’ Tolerance to Cold Stress at the Seedling Stage

Rice plants are affected by low-temperature stress during germination, vegetative growth, and reproductive stages. Thirty-nine rice genotypes including 36 near-isogenic lines (NILs) of BRRI dhan29 were evaluated to investigate the level of cold tolerance under artificially induced low temperature at the seedling stage. Three cold-related traits, leaf discolouration (LD), survivability, and recovery rate, were measured to determine the level of cold tolerance. Highly significant variation among the genotypes was observed for LD, survivability, and recovery rate. Three NILs, IR90688-74-1-1-1-1-1, IR90688-81-1-1-1-1-1, and IR90688-103-1-1-1-1-1, showed tolerance in all three traits, while IR90688-118-1-1-1-1-1 showed cold tolerance with LD and recovery rate. IR90688-92-1-1-1-1-1, IR90688-125-1-1-1-1-1, IR90688-104-1-1-1-1-1, IR90688-124-1-1-1-1-P2, IR90688-15-1-1-1-1-1, and IR90688-27-1-1-1-1-1 showed significantly higher yield coupled with short growth duration and good grain quality. Genetic analysis with SSRs markers revealed that the high-yielding NILs were genetically 67% similar to BRRI dhan28 and possessed cold tolerance at the seedling stage. These cold-tolerant NILs could be used as potential resources to broaden the genetic base of the breeding germplasm to develop high-yielding cold-tolerant rice varieties.

Effect of Nitrogen on the Growth and Yield of Local Aman Rice Cultivar

To identify suitable nitrogen management practices for local fine and aromatic rice cultivars an experiment was carried out at Farmer’s field at Jointapur, Sylhet region of Bangladesh during the period from August 2017 to December 2017. The experiment was replicated thrice in randomized complete block design assigning factor A: rice cultivars viz. Beruin (V1), Moinasail (V2), Nagrasail (V3) and, BRRI dhan49 (Control, check variety) (V4) and factor B: N sources viz. N 100% chemical (F1) , 50% N from FYM + 50% from Urea (F2) , 50% N from Vermicompost+ 50% from Urea (F3) and farmers practice (F4). Nutrients P,K, S and Zn (100%) were supplied from chemical sources of triple super phosphate, muriate of potash, gypsum and zinc sulphate, respectively. Only N was supplied from different organic and inorganic (urea) sources. Fertilizers were applied at the rate of 140-33-38 kg ha-1 of NPK for farmers’ practice, 90-15-60-12-1 kg ha-1 N, P, K, S and Zn for the variety of BRRI dhan49 and 45-9-33-9-1 kg ha-1 N, P, K, S and Zn for 3 local rice varieties. The results indicate that, BRRI dhan49 (V4) gave the highest yield (2.97 t ha-1) among the varieties. Among the local varieties Nagrasail (V3) gave the highest yield (2.24 t ha-1). In case of farmers practice, highest grain yield was obtained F4 (3.50t ha-1) followed by F1 (2.32 t ha-1). Interaction effect also revealed, the highest grain yield (3.23 t ha-1) in (V4× F4). Among the local varieties Nagrasail gave highest grain yield (2.58 t ha-1) along with F4. Farmer’s practice fertilizer management is a promising option, and Nagrasailis the best one for local T. aman cultivars cultivation in Sylhet region of Bangladesh.

Effect of zinc and boron management on yield and yield contributing characters of Aus rice (Oryza sativa)

Zinc (Zn) and boron (B) are two of the most important micronutrients for plants which play vital role in various metabolic functions. However, deficiency of these nutrients elements in agricultural soils is very common and it has been associated with lower yield of rice in many regions of the world. Therefore, a field experiment was carried out at the Agronomy Field Laboratory of Bangladesh Agricultural University, Bangladesh during the period from May 2019 to August 2019 to study the effect of different levels of Zn and B fertilizers on the yield of Aus rice (cv. BRRI dhan48). The experiment included four levels of Zn fertilizer (ZnSO4.7H2O) management and three levels of boron fertilizer (boric acid) management. The Zn treatments were 0 kg/ha (control), basal application @ 10 kg/ha, basal application @ 5 kg/ha + soil application during active tillering stage @ 5 kg/ha, and foliar application (0.5% solution of ZnSO4.7H2O) during flag leaf stage. The B fertilizer managements were 0 kg/ha (control, 1.5 kg/ha basal application, and foliar application of 2% solution of H3BO3 during flag leaf stage. The experiment was laid out in a randomized complete block design (RCBD) with three replications. Zn and B boosted all studied parameters of rice in comparison to their controls, i.e., no fertilization. The highest values for grain yield and almost all yield contributing characters of rice were obtained from foliar application of H3BO3 during flag leaf stage. The highest number of filled grains/panicle and grain yield were obtained from foliar application of ZnSO4.7H2O. The results also showed that grain yield of rice increased with increasing levels of both Zn and B up to 4.39 t/ha and 4.29 t/ha, respectively. For the maximum grain yield of Aus rice cv. BRRI dhan49, 2% solution of H3BO3 coupled with 0.5% of ZnSO4.7H2O solution should be applied during flag leaf stage. Further research should be conducted on different agro-ecological zones to assess the interaction between Zn and B in different soil types.

Characterization of Bangladeshi Aus rice landraces under drought stress

Genetic diversity is a prerequisite for crop improvement. This study, which was carried out at Patuakhali Science and Technology University, Bangladesh, explored the genetic diversity of 38 Bangladeshi aus rice (Oryza sativa L.) landraces under drought stress by using phenotypic and simple sequence repeat (SSR) markers. Nonhierarchal clustering analysis with Mahalanobis‟ D2 statistic based on the data of morphological traits divided the studied landraces into four groups. High variability was found among the groups. Group 3 had the highest number of tillers per plant, spikelets per panicle, and panicle length. Group 2 had high 100-seed weight, and group 4 showed the highest yield per plant. Spikelets per panicle showed the maximum variation among all of the traits in the four groups. Principal component analysis showed that PC1 contributed 32.24% of the total variation, whereas PC2 accounted for 26.20%. Compared with the other traits, plant height, spikelet per panicle, and yield per plant exhibited a greater influence on the phenotypic variation observed in PC1. Compared with other traits, 100-grain weight, days to harvesting, and days to 50% flowering contributed highly to the variation found in PC2. In SSR analysis, the highest polymorphism information content (PIC) of 0.87 was observed for markers RM207 and RM256 and the lowest PIC of 0.64 was observed for markers RM212 and RM274. „Madab jata‟ showed the highest similarity value (0.7) with „BRRI dhan 42.‟ „Lonka gora binni‟ exhibited a similarity value of 0.588, and „Koba binni,‟ „Parija‟, „Gota irri,‟ „Chitri‟, and „Putiraj‟ presented a similarity value of 0.556 with „BRRI dhan 42‟. Among these genotypes, „Madab jata,‟ „Lonka gora binni,‟ and „Koba binni‟ formed a cluster with „BRRI dhan 42‟ with the coefficient of 0.53. Therefore, „Madab jata,‟ „Lonka gora binni,‟ and „Koba binni‟ might contain drought-tolerant alleles and can be used for future research programs. The high genetic variability obtained in this work indicates that the studied rice genotypes contain drought-tolerant alleles and could be used for breeding drought-tolerant rice cultivars.

Performances of Boro Rice as Affected by Different Concentrations of Marine Water

Salinity is one of the most devastating abiotic stresses limiting crop production. Considering this issue, a pot experiment was conducted at Sher-e-Bangla Agricultural University, Dhaka, Bangladesh during the boro season (2017-2018) using two rice(Oryza sativa L.) varieties, namely BRRI dhan28 (salt sensitive) and BRRI dhan47 (salt tolerant),to assess the effects of varied salinity levels on the growth and the performance of the rice varieties under salt stress conditions. Four salinity treatments were used in this experiment, viz. control S0 (only freshwater), quarter-strength marine water S1 (three-parts freshwater and one-part marine water; 7.5 ds m−1), half-strength marine water S2 (half freshwater and half marine water; 15 ds m−1), and full-strength marine water S3 (only marine water; 30 ds m−1).These mixtures were used for irrigation purposes throughout the life cycle of the plants. Salt stress significantly decreased the plant height, relative water content (RWC) of leaves, number of effective tillers hill−1, number of filled grains panicle−1, 1000-grain weight, grain yield, straw yield, and biological yield of the rice. In both rice types, plant growth and yield were reduced as the salinity level increased. Grain yields decreased by 50, 90, and 100% in BRRI dhan28 when irrigated with quarter strength, half strength, and full-strength seawater, respectively, but decreased by 27, 50, and 72%, respectively, in BRRI dhan47. Similarly, other yield attributes had higher reductions in BRRI dhan28 under salt stress conditions than BRRI dhan47. However, irrigation with marine water in rice might lead to some straw yield but produced little to no grain.

Comparative Physiology of Indica and Japonica Rice under Salinity and Drought Stress: An Intrinsic Study on Osmotic Adjustment, Oxidative Stress, Antioxidant Defense and Methylglyoxal Detoxification

Salinity and drought stress are significant environmental threats, alone or in combination. The current study was conducted to investigate the morpho-physiology, osmotic adjustment, oxidative stress, antioxidant defense and methylglyoxal detoxification of three rice genotypes from the indica (cv. BRRI dhan29 and BRRI dhan48) and japonica (cv. Koshihikari) groups. Eighteen-day-old seedlings of these genotypes were exposed to either in alone salinity (150 mM NaCl) and drought (15% PEG 6000) or in the combination of salinity and drought (150 mM NaCl + 15% PEG 6000) stress in vitro for 72 h. Compared with the control, the water status, biomass and photosynthetic pigments were decreased, where a significant increase was seen in the mortality rate, hydrogen peroxide content, electrolyte leakage, lipoxygenase activity, level of malondialdehyde and methylglyoxal, indicating increased lipid peroxidation in rice genotypes in stress conditions. The non-enzymatic and enzymatic components of the ascorbate-glutathione (AsA-GSH) pool in rice genotypes were disrupted under all stress treatments, resulting imbalance in the redox equilibrium. In contrast, compared to other rice genotypes, BRRI dhan48 revealed a lower Na+/K+ ratio, greater proline (Pro) levels, higher activity of AsA, dehydroascorbate (DHA) and GSH, lower glutathione disulfide (GSSG) and a higher ratio of AsA/DHA and GSH/GSSG, whereas enzymatic components increased monodehydroascorbate reductase, dehydroascorbate reductase, glutathione peroxidase and glyoxalase enzymes. The results showed that a stronger tolerate ability for BRRI dhan48 against stress has been connected to a lower Na+/K+ ratio, an increase in Pro content and an improved performance of the glyoxalase system and antioxidant protection for scavenging of reactive oxygen species. These data can give insight into probable responses to single or combination salinity and drought stress in rice genotypes.

Established Rice Ratoon for Improving Cropping Intensity and Income

Transplanted aman rice suffers from frequent flash flood damage in northern Bangladesh and thus grain yield decreases. An experiment was conducted at the RDRS Farm, Rangpur, Bangladesh to evaluate production opportunity and income generation from growing ratoon rice in between boro and aman seasons during May to July in fallow land as additional harvests. Ratoon seedlings of ACI-2 boro hybrid rice was transplanted and tested against the performance of conventional transplanted BR11 and BRRI dhan46. BR11 gave higher grain yield and profit than ratoon cropping. However, ratoon crop required only 75-80 days for maturity. Thus, it would be possible to incorporate rice ratoon cropping in fallow lands immediately after harvest of boro rice in April- May as additional crop. After harvests of the ratoon rice, farmers can grow traditional aman varieties as conventional practice. If ratoon of ACI-2 (hereafter ratoon rice)-BRRI dhan46 cropping system is practiced then total grain yield from the system was 8.42 t ha-1, which was almost double than conventional BR11 or BRRI dhan46 cultivation. Total net income of boro and ratoon rice-BRRI dhan46 system was also higher (Tk 55,090 ha-1) compared to traditional BR11 aman rice cultivation (Tk 35,802 ha-1). The overall result indicated that just immediate after boro rice harvests, growing rice from ratoon seedlings of ACI-2 followed by BRRI dhan46 in aman season provided higher net profit than traditional cultivation of BR11. The result also implies that growing rice by using ratoon seedlings can ensure three harvests (boro rice-ratoon rice-aman rice) in the same year instead of growing two traditional rice (boro rice-aman rice) crops in a year with additional net profit of Tk 19,288 ha-1 year-1. Moreover, use of rice ratoon seedlings might help farmers in intensification of crop in flash flood prone areas of the country. Ann. Bangladesh Agric. (2021) 25 (1) : 33-41

Effect of Row Arrangement and Integrated Nutrient Management on the Growth of Aromatic Fine Rice cv. BRRI dhan 34

Effect of Row Arrangement and Integrated Nutrient Management on the Growth of Aromatic Fine Rice cv. BRRI dhan 34

Morpho-molecular diversity study of rice cultivars in Bangladesh

Rice is one of the frontline cereals in the world and the major cultivated crop in Bangladesh. A total of eleven simple sequence repeats (SSRs) and thirteen sequence-tagged site (STS) markers were used to characterize twenty-four rice cultivars in Bangladesh. Twenty-four markers generated 60 alleles with 2.5 alleles per locus. The average polymorphism information content (PIC) value was 0.40, while the mean value of heterozygosity, gene diversity, and major allele frequency were recorded as 0.10, 0.48 and 0.62, respectively. However, the SSR markers showed more specificity and a higher discrimination power than the STS markers. The cluster analysis displayed four major clusters with a genetic similarity coefficient value of 0.73. The morphological analyses of the grain identified that Binadhan-20 and BRRI dhan34 had the longest and the shortest seed size, respectively, with a variable correlation between the seed length, width and length/width ratio. The phenol reaction test distinguished seven cultivars as japonica and seventeen cultivars as indica or an intermediate type. All these results regarding the phenotypic data and marker information will be useful for parental selection in modern rice breeding programmes.

Effect of salinity on morpho-physiological traits at reproductive stages of Oryza sativa

Soil salinity is one of the most adverse environmental problems which restricts crop yield. Salinity affects rice plants very badly from germination to its maturity. Therefore, a pot experiment was conducted to study the salinity tolerance of rice genotypes viz. SAL655, STL15, PBRC37, Binadhan-8 and BRRI dhan28. The plants were grown under four salinity levels (0, 6, 9 and 12 dSm−1). Plant height, total number of green leaves hill−1, root dry weight, stem dry weight, total dry weight per hill, root shoot ratio was found to be decreased gradually with gradual increase in salinity levels as compared to the control. The genotype Binadhan-8 and PBRC37 showed the better performance in respect of all the parameters than other genotypes. Therefore, Binadhan-8 and PBRC37 were found more tolerant than other genotypes to salt stress.
 Progressive Agriculture 32 (2): 117-126, 2021

Agro-Economic Productivity of Rice- Rabi Croprice Systems in Northwestern Drought-Prone Areas of Bangladesh

Productivity and economics of different rabi crop-based systems were evaluated at farmers’ field in Durgapur upazilla of Rajshahi district, Bangladesh to select the best rabi crop(s) for fitting in the T. Aman rice - rabi crop – DDS Aus rice pattern. Nine rabi crops namely, (1) Mustard, (2) Potato, (3) Lentil, (4) Field pea, (5) Radish, (6) Cabbage, (7) French bean, (8) Carrot and (9) Tomato were cultivated during the rabi season in between the two rice crops to form nine cropping patterns. The experiment used Randomized Complete Block Design (RCBD) with three replications. Aman rice variety BRRI dhan57 was transplanted on 12 July 2017 and harvested on 28 October 2017, while, Aus rice variety BRRI dhan28 was sown in the dry cultivated land on 16 March 2018 and harvested on 24 June 2018 while rabi crops were sown/transplanted on 28 November 2017. Proper agronomic management practices were adopted for all the crops in the patterns. Data on yield and related attributes of DDS Aus rice were recorded at harvest. In addition, the yield of Aman rice and all the rabi crops were recorded. In addition, rice equivalent yield of each rabi crop, system yield (total yield of all the crops in the sequence), cost of production, gross return and benefit cost ratios (BCR) of all the patterns were recorded. Results revealed that yield of dry direct seeded Aus rice cv. BRRI dhan28 did not differ significantly due to different rabi crops grown under the respective patterns. The system yield was the highest in T. Aman rice –tomato – DDS Aus rice pattern (19.62 t ha-1) and the lowest with T. Aman rice -mustard – Aus rice pattern (14.63 t ha-1). Since the market price of a rabi crop changes from year to year, the net profit of a pattern depends on the yield of a crop grown in rabi season. Therefore, any of the nine rabi crops under the trial can be successfully cultivated in between the two rice crops under Aman rice – rabi crop –Aus rice patterns. However, the present study concludes that any of the nine rabi crops can be grown in between the two rice crops but carrot, French bean, mustard, field pea, and tomato could be the most profitable ones for the T. Aman rice – rabi crops –DDS Aus rice patterns. SAARC J. Agric., 19(2): 85-94 (2021)

Effect of Plant × Row Spacing on Two Varieties of Boro Rice

A field study was undertaken at Bangladesh Agricultural University, Mymensingh during the season November 2017 to April 2018 to evaluate the effects of plant × row spacings on yield and yield contributing traits of two Boro rice varieties. Two rice varieties viz., BINA dhan-10 and BRRI dhan28 were sown in five plant spacings viz. 25 cm × 15 cm, 25 cm × 25 cm, 30 cm × 30 cm, 35 cm × 35 cm, 40 cm × 40 cm in randomized completely block design with factorial fashion with three replications. Growth performances, yield contributing characters and yield were significantly influenced by varieties and plant spacings. The highest grain yield (8.75t ha-1), straw yield (11.56 t ha-1), biological yield (20.31 t ha-1) and harvest index (43.05 %) were obtained from the variety BINA dhan- 10 sown at planting spacing of25 cm × 15 cm. More number of total tillers hill-1(14.75) and number of effective tiller hill-1 (12.87) were recorded from the variety BINA dhan-10 sown at planting spacing 40 cm × 40 cm. Based on the present study it is suggested that BINA dhan-10 may be grown under 25 cm × 15 cm in order to get maximum grain yield for Boro rice cultivation. SAARC J. Agric., 19(2): 95-106 (2021)

Genetic Analysis of Submergence Tolerance Rice Genotypes by Introgression of Sub1 QTL to Indica HYV through Breeding Populations (F2) with Marker Assay

More than 2.0 million-hectare area was affected by flash floods of various grades and reduced the average yield in Bangladesh by 5%. It involves introgression of Sub1 QTL into the genetic background of HYV rice through marker-assisted breeding and to evaluate submergence tolerance of high yielding rice varieties. SSR profiling was performed to tag the submergence tolerant QTL by using sub1 flanking markers and F1 confirmation of Binadhan-7 x BRRI dhan52 (F1) by using the primer RM1115. The gene diversity value was 0.7610 and the polymorphism information content (PIC) values were 0.7432 & allele frequencies (%) were 0.3328. Binadhan-7 x BRRI dhan52 (F2) crosses were possessed the highest grain yield plant-1 (38.00 g) which was significantly higher than its both parents and also early maturing as 124 days from all crosses. The genetic similarity analysis using UPGMA (Unweighted Pair-Group Method using the Arithmetic Average) clustering system generated 5 major genetic clusters. Maximum intra-cluster degree of diversity was observed in cluster4 (79.93) and minimum in cluster3 (31.44). Highly significant and positive correlations were found among the grain yield (GY) and Total tillers/plant, effective tillers/plant, panicle length, and filled grains/panicle. The first three principal components with Eigen-values explained 73.7 % of the total variation among 16 rice genotypes for the 9 quantitative traits studied. However, it is hoped that promising Sub1 cross combination Binadhan-7x BRRI dhan52 will be able to develop three to four weeks tolerance with high yielding submergence tolerant varieties to increase rice production in submerged prone areas of Bangladesh where single flash floods occur under different cropping patterns.

Growth, Grain Development and Yield Performance Of Boro Rice Varieties Under Water Stress Condition

A field experiment was conducted at the Agronomy field, Sher-e-Bangla Agricultural University, Dhaka to evaluate the effect of water stress at reproductive stage on growth, grain development and yield of Boro rice. The experiment consisted of two factors: Factor A: Water stress viz. no water stress (W1) and water stress (W2) and Factor B: Variety viz. BRRI dhan28 (V1), BRRI dhan29 (V2), BRRI dhan50 (V3), Binadhan-10 (V4), BRRI hybriddhan3 (V5), Aloron (V6). In no water stress, irrigation water was maintained strictly from transplanting time to harvesting time while in water stress condition; supply of irrigation was stopped just after flowering upto harvest. Results showed that growth, grain development and yield of Boro rice were significantly affected by water stressed condition. All the tested varieties performed better under no water stress condition compared to water stress condition. About 7% panicle weight was decreased due to water stress condition at reproductive stage. Grain development of BRRI dhan29 was least affected by water stress while the most affected variety was Binadhan-10. Water deficit at reproductive stage reduced about 15-22% grain yield of tested varieties. Aloron was the least affected variety due to water stress while BRRI dhan50 was the most affected variety. The variety Aloron provided equal yield (7.31 t ha-1) under stress condition as given by BRRI dhan29 under no water stress condition. So, Aloron may be a better option to cultivate in the region where irrigation water is scarce or costly.
 Bangladesh Agron. J. 2021, 24(2): 99-107

Performance of Two Aman Rice Varieties Using Varying Plant Density in the Northeastern Region Of Bangladesh

The experiment was conducted to assess the performance of two popular rice varieties with varying spacing at a farmer's field in Darbost union of Jaintapur Upazila under the Sylhet district of Bangladesh during aman season 2016. Two aman rice varieties (BRRI dhan34 and Binadhan-17), and four levels of plant density (15×10 cm, 20×10 cm, 20×15 cm, and 25×15 cm) were tested in a factorial randomized complete block design (RCBD) with three replications. The results indicated that yield and yield attributes of rice differed significantly due to varieties, spacing, and their interaction. It was recorded that var. Binadhan-17 showed maximum flag leaf length (34.33 cm), maximum number of filled grains m−2 (27855), maximum grain weight m−2 (654.58) contributed to increase grain yield (6.55 t ha−1) in closer spacing (20×10 cm), which ultimately increased grain yield. Therefore, the results of the present study suggested that rice var. Binadhan-17 could be transplanted at 20×10 cm spacing for getting maximum yield (6.55 t ha−1) in northeastern region of Bangladesh.
 Bangladesh Agron. J. 2021, 24(2): 1-12

Characterization of Multiple Grain Rice (Oryza sativa L.) Biramsundari from Bangladesh

Biramsundari is a rice germplasm from Bangladesh showing one to four grain in a single seed. Comparative study of morphological traits revealed that BS is a taller rice variety compared to modern rice varieties with longer and wider flag leaves, longer panicle length and higher thousand seed weight (TSW) than transplanted aman rice variety BRRI dhan 49. Flower morphological analysis unveil that multiple grains of Biramsundari are originating from multiple number of carpels in each floret. About 40.1% flower contains three carpels. Fluorescent microscopic study also confirms the zygotic origin of multiple grain formation in Biramsundari. Molecular characterisation of Biramsundari was performed by using TeaCpSSR27 and TeaCpSSR28 chloroplast microsatellite markers. The results of this investigation reveal that atpF and rsp14-psaB intergenic spacer regions of Biramsundari have variation compared to sequences of with O. sativa ssp. indica, O. sativa ssp. japonica and O. rufipogon. Plant Tissue Cult. & Biotech. 31(2): 115-122, 2021 (December)