The study was conducted to investigate genetic variability among 113 aromatic and fine local rice genotypes of which five were exotic in origin. The test genotypes were evaluated for 19 growth traits, yield components, and yield. All the quantitative traits varied significantly among the test genotypes. High heritability along with high genetic advance was observed for flag leaf area, secondary branches per panicle, filled grains per panicle, grain length, grain breadth, grain length breadth ratio, and 1000 grain weight. Such findings suggested preponderance of additive gene action in gene expression for these characters. Grain yield was significantly and positively correlated with days to flowering, days to maturity, panicle length, filled grains per panicle, and 1000 grain weight. According to D 2 cluster analysis, 113 test genotypes formed 10 clusters. Selection of parents from the clusters V and X followed by hybridization would possibly result in desirable heterosis for the development of heterotic rice hybrids. Finally, molecular characterizations of the studied germplasm are required for high resolution QTL mapping and validating the presence of candidate genes responsible for valuable characters.

While the pleasant scent of aromatic rice is making it more popular, with demand for aromatic rice expected to rise in future, varieties of this have low yield potential. Genetic diversity and population structure of aromatic germplasm provide valuable information for yield improvement which has potential market value and farm profit. Here, we show diversity and population structure of 113 rice germplasm based on phenotypic and genotypic traits. Phenotypic traits showed that considerable variation existed across the germplasm. Based on Shannon–Weaver index, the most variable phenotypic trait was lemma-palea color. Detecting 140 alleles, 11 were unique and suitable as a germplasm diagnostic tool. Phylogenetic cluster analysis using genotypic traits classified germplasm into three major groups. Moreover, model-based population structure analysis divided all germplasm into three groups, confirmed by principal component and neighbors joining tree analyses. An analysis of molecular variance (AMOVA) and pairwise FST test showed significant differentiation among all population pairs, ranging from 0.023 to 0.068, suggesting that all three groups differed. Significant correlation coefficient was detected between phenotypic and genotypic traits which could be valuable to select further improvement of germplasm. Findings from this study have the potential for future use in aromatic rice molecular breeding programs.

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and it was 1.48 for HYV"s. The number of different allele ranged from 3.56 (Dhaliboro) to 7.80 (Balam), while the number of effective allele from 2.63 (Dhaliboro) to 5.11 (Balam) and it was 5.18 and 4.14 for H YV population, respectively. Analysis of molecular variance showed that the maximum percentage of variation was present among individuals within populations (85%), followed by among populations (15%). The spearman"s rank correlation coefficient was found highly significant (rs=0.51; t=2.9 8) between ranking of inter-genotype (D=√D2) and Nei's genetic distances, indicating strong association between them. The correlation tests revealed that SSR diversity analysis is the most powerful method for grouping. But, combination of quantitative and molecular methods may be the best. Finally, 21 core collections were selected from Balam group . The selected core accessions need to conserve as active collection in Genebank, utilize as parents in hybridization programs and develop QTL map for unlocking valuable genes.

To study combining ability effects of developed CMS and restorer lines an experiment was carried out at the experimental farm, Department of Genetics and Plant Breeding, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Salna, Gazipur during Aman 2011 and Boro 2011-12 following RCBD design through line × tester analysis in three replications. Five known CMS lines and sixteen developed Restorer lines were considered for through line × tester analysis. Among sixteen restorer lines, only four showed significant negative GCA effects for all these three traits for earliness. The estimated of gca effects of parents indicated that seven parents and sixteen crosses contributed highly significant negative effects for plant height which were responsible for dwarfing character. Fifteen crosses and eight parents showed significant negative sca estimates for days to first flowering and twenty crosses for maturity. Considering both SCA effects and per se performances for days to 1st flowering and maturity; the crosses of IR 58025A with RG-BU08-005R, RG-BU08-006R, RG-BU08-016R, RG-BU08-018R and RG-BU08-025R were found as the best specific combiner. Among 80 crosses fifty two crosses showed significant positive SCA effects along with above average perse performances for grain yield. Ten crosses of IR 58025A, seven crosses of GAN46A, fourteen crosses of IR 62829A, nine crosses of IR 68888A and ten crosses of BRRI 1A showed significant positive SCA effects along with mean values resulting significant positive SCA effects and above average perse performances with all five CMS lines for grain yield.