SRINIVAS, Dr. T.. SUDEEPTHI, K2021-12-082021-12-082021-12-08https://krishikosh.egranth.ac.in/handle/1/5810178845GENETICS OF ANAEROBIC GERMINATION TRAITS IN RICE (Oryza sativa L.)The present investigations were undertaken at Regional Agricultural Research Station, Maruteru, West Godavari District of Andhra Pradesh, during 2017-2019. Anaerobic germination screening of 107 rice genotypes revealed MTU 1140, MTU 2716, PLA 1100, RTCNP 28 and RTCNP 50 to be tolerant for anaerobic germination with superior germination per cent, shoot length, root length and seedling dry weight in addition to seedling vigour index and anaerobic response index, compared to other genotypes and hence, were found promising for use in direct seeding under wet conditions. The genetic variability studies revealed narrow difference between PCV and GCV for majority of the traits. High genotypic and phenotypic coefficient of variation along with high heritability coupled with high genetic advance as per cent of mean was exhibited by germination per cent, root length, seedling dry weight, seedling vigour index, anaerobic response index and number of ear bearing tillers per plant. Character association and path studies revealed germination per cent and shoot length to be effective selection criteria for improvement of seedling vigour index, while, number of ear bearing tillers per plant, total number of grains per panicle and test weight were found to be important for improvement of grain yield per plant. The diversity analysis for anaerobic germination traits using Mahalanobis D2 grouped the 107 rice genotypes studied, into nine clusters. The mode of distribution of genotypes was observed to be at random. Hybridization of genotype of cluster IX (MTU 1140) with genotypes of cluster VII (MTU 1010, MTU 1156, NONA BOKRA, SM 10, SM 14) were expected to result in transgressive segregants due to their high diversity. Maximum genetic diversity was contributed by shoot length, followed by seedling dry weight, anaerobic response index, germination per cent and root length. The PCA analysis revealed two principal components with eigen values more than xvii one contributing to 77.662 per cent of the total variability. Further, the study identified germination per cent, shoot length, anaerobic response index and root length as the maximum contributing traits towards the existing variability. Mahalanobis D 2 for yield and yield component traits grouped the 107 rice genotypes into seven clusters. Maximum inter-cluster distance was observed between cluster II and III indicating that genotypes from these clusters were highly divergent meriting their consideration in selection of parents for hybridization. Minimum intercluster distance was observed between cluster VI and VII, while, the genotypes included in cluster IV exhibited maximum intra-cluster distance. Hybridization between MTU 1153, MTU 1156, MTU 1010, MTU 3626, FL 478, MTU 7029, MTU 1001 of cluster II and the genotype, RTCNP 35 of cluster III are expected to result in greater variability and transgressive segregants. Days to 50 per cent flowering contributed maximum to total divergence. The PCA analysis revealed three principal components with eigen values greater than one contributing to 69.412 per cent towards the total variability. Further, the study also identified the maximum contributing traits towards the existing variability as panicle length, days to 50 per cent flowering, number of ear bearing tillers per plant, plant height and test weight. Molecular characterization studies of 107 rice genotypes with 30 anaerobic germination linked SSR markers revealed 18 SSR markers to be highly polymorphic. Further, a total of 49 reproducible polymorphic alleles were amplified with an average of 2.72 alleles per locus with these 18 polymorphic SSR markers. An analysis of the UPGMA (Unweighted Pair Group Method with Arithmetic Mean) based dendrogram revealed grouping of the 107 genotypes into two major clusters. The cluster diagram revealed additional sub clusters (11) in Cluster I. The genotypes, MTU 1140, PLA1100, SM-2 and RTCNP-28 which had recorded more than 80 per cent germination under anaerobic conditions of submergence for 14 days, gave similar amplification bands at 330bp with RM 23877 anaerobic germination linked marker. The markers, RM 23877, RM 6318, RM 17403, RM 5361, RM 6737 and RM 149 with high PIC value were found to be highly informative markers (PIC > 0.50) with potential for identification of anaerobic germination tolerance genotypes. Gene action studies for anaerobic germination traits revealed inadequacy of simple-additive dominance model for majority of the traits studied in most of the crosses, based on the significance of scaling tests A, B and C. In general, dominance effects (h) had exceeded the corresponding additive effects (d) in almost all the crosses. Presence of duplicate type of epistasis was noticed in most of the crosses for most of the traits. Scaling tests and gene action studies for yield and yield component traits also revealed the inadequacy of simple-additive dominance model for majority of the traits studied in most of the crosses. However, the adequacy of simple additive-dominance model was observed for few crosses with respect to number of ear bearing tillers per plant, panicle length and test weight. The results also revealed the pre-ponderance of dominant gene action (h) for majority of the traits in most of the crosses studied. The gene interaction studies revealed the pre-dominance of dominance x dominance (l) gene action for grain yield and majority of the yield traits studied in most of the crosses. Further, duplicate epistasis was noticed for majority of the traits studied in most of the crosses.EnglishThesis