KRISHNAVENI, BBALA KANAKA VENKATA MANI, D2020-02-292020-02-292019http://krishikosh.egranth.ac.in/handle/1/5810143981D5923The present investigation was carried out during kharif, 2018 at Agricultural College Farm, Bapatla with 119 recombinant inbred lines along with parents (BPT 2231 and MTU 1001) to elicit information on the nature and extent of variability, heritability, genetic advance for yield, yield components and identification of genomic regions linked to dormancy related traits in rice. The analysis of variance indicated significant differences among RIL population along with parents for majority of traits studied indicating that the data generated from the above material shall represent wide variability. The estimates of phenotypic coefficient of variation for all the characters under study were high than the genotypic coefficient of variation and the variation is less between these two estimates indicating meager influence of environment on the expression of these traits. The results of genetic parameters among yield components and dormancy related traits revealed high heritability coupled with high genetic advance as per cent of mean for number of ear bearing tillers per plant, grain yield per plant, germination (%) at 5 days and 10 days after harvesting, free amino acid (mg/100g) and total soluble sugars (mg/100g) indicating the operation of additive gene action in the inheritance of the trait. Hence good response to selection can be anticipated for improvement of these traits. Identification of genomic regions/QTL involves comparative studies on phenotyping and genotyping data of large mapping populations. The phenotyping studies were conducted at 5 days and 10 days after harvesting. Based on the germination (%), the entire RIL population was divided into 3 categories viz., strongly dormant lines (germination below 50%) moderately dormant lines (germination 50-79%) and weakly dormant lines (germination above 80%). Among all these, the line SD 12 exhibited below 10% of germination whereas the dormant parent MTU 1001 recorded 25% germination at 10 days after harvesting. Hence, this can be exploited in future breeding programme as this line also recorded on par with grain yield when compared with parents. Among the RIL‟s under study, 7 lines viz., SD 20 (37.94 g), SD 30 (36.75 g), SD 32 (39.13 g), SD 45 (41.27 g), SD 59 (41.74 g), SD 65 (41.02 g) xiii and SD 80 (39.75 g) which recorded significantly superior grain yield than the parents coupled with strong dormancy period of 10 days may be tested for their suitability in coastal regions in during kharif season in future breeding programmes. The parental polymorphism survey was conducted with 188 SSR markers including 72 trait linked and 116 random markers distributed all over 12 chromosomes of rice. Among these, 10 markers manifested polymorphism between the parents with difference in the length of amplified product which is high for marker RM22565 followed by RM3295 and RM346. The contrasting bulks for the target trait were prepared (i.e., Low dormancy bulk and High dormancy bulk) based on the germination (%) at 5 days and 10 days after harvesting and physiological parameters i.e. free amino acids and total soluble sugars of RIL population. Out of these 10 polymorphic markers screened, four markers viz., RM346, RM22565, RM7051 and RM10793 co-segregated among the individual recombinant inbred lines constituting respective bulks. Hence, these four markers were used for genotypic studies of RIL population. The genotyping studies of RIL population revealed that the RM22565 recorded 60% similarity between the phenotyping and genotyping. Among the RIL population under study, three lines viz., SD 3, SD 15 & SD 113 manifested similar amplicon size with the dormant parent MTU 1001 when amplified with two markers viz., RM346 and RM7051. Likewise, four lines viz., SD 55, SD 68, SD 72 and SD 113 exhibited similar banding pattern with MTU 1001 when amplified with RM346 and RM22565. The line SD 113 also manifested similar banding pattern with that of MTU 1001 when it was amplified with 3 markers viz., RM346, RM22565 and RM7051 while SD 72 and SD 87 exhibited similar bands with RM346, RM22565 and RM10793. Among the 119 RIL population studied, one line i.e. SD 12 manifested banding pattern as that of the dormant parent MTU 1001 with all the four polymorphic markers viz., RM346, RM22565, RM7051 and RM10793. Considering both phenotyping as well as genotyping studies and bulk segregant analysis, it may be concluded that the identified recombinant inbred lines which showed high dormancy also exhibited similar banding pattern as that of dormant parent MTU 1001 with four markers viz., RM346, RM22565, RM7051 and RM10793 on chromosome 7, 8, 4 and 1 respectively indicating that these chromosomal regions may be harboring the genes/QTL‟s responsible for the strong dormancy in the above lines. Among the polymorphic markers used in the parental study, one marker i.e. RM346 was identified and used as dormancy linked marker in previous studies. But the other 3 markers viz., RM22565, RM7051 and RM10793 were not reported in the earlier studies and hence these three markers may be identified as novel markers linked to dormancy trait suggesting that these markers may also be utilized as linked markers for dormancy related traits in marker assisted breeding programmes. The entire genotypic data was scored and analyzed using single marker analysis to know the marker trait association. The marker RM22565 (P<0.0001) on chromosome 8 reported significant association with germination (%) at 5 days after harvesting at a mapping position of 5,796,298-5,796,574bp (5 cM) using single marker analysis. Hence, it may be concluded that the chromosomal region linking to marker RM22565 on chromosome 8 may be associated with the genes linked to the dormancy related traits and it‟s usefulness in the marker assisted selection to screen the genotypes/cultivars to identify the strongly dormant genotypes.en-USnullThesis