Suresh, J.Anil Kumar2024-05-062024-05-062023-03-25https://krishikosh.egranth.ac.in/handle/1/5810208711In the present study, 42 rice entries comprised of land races, released varieties and advanced breeding lines including susceptible check (TN 1) and resistant check (Aganni) were evaluated in a replicated trial against gall midge biotype, GMB3 at Regional Agricultural Research Station (RARS), Jagtial under field conditions during kharif 2021. Based on field screening, selected entries were genotypically characterized by using Gm3, Gm4 and Gm8 based functional SSR markers for presence/absence of resistant gene(s). Further these 42 entries were subjected to genetic divergence, correlation and path analysis during rabi, 2021-22 at RARS, Jagtial. Among 42 entries, four entries viz., Kakai, WGL-1145, WGL-1147 and WGL-1127 had nil damage and they had shown high resistant against GMB3 in field condition. Two entries viz., IR72476-B-P-9-3-1-1 and RP-5332-54-11-8-2-13 were found resistant against GMB3. Promising test lines when genotypically characterized by using Gm3, Gm4 and Gm8 gene linked molecular markers for presence/absence of resistant gene(s), revealed in presence of Gm1 gene in two genotypes like IR72476-B-P-9-3-1-1 and WGL-1145; Gm4 gene in four genotypes like Kakai, WGL-1145, WGL-1147 and WGL-1127 and Gm8 gene in in five genotypes like RP-5332-54-11-8-2-13, Kakai, WGL-1145, WGL 1147 and WGL-1127. Analysis of variance revealed significant variability among the genotypes for all the traits studied indicating presence of high variability among the rice genotype. The genotypic coefficients of variation for all the characters studied were lesser than the phenotypic coefficients of variation indicating the modifying effect of the environment in association with the characters at genotypic level. High PCV coupled with high GCV observed for number of grains per panicle, 1000 grains weight, grain yield per plant, head rice recovery and kernel L/B ratio suggesting the presence of wide variability among the genotypes with regard to these characters. High heritability coupled with high genetic advance as per cent of mean was observed for the characters like plant height, number of Name of the author : ANIL KUMAR Title of the thesis : “GENETIC ANALYSIS AND IDENTIFICATION OF GENOTYPES WITH NOVEL SOURCES OF RESISTANCE FOR GALL MIDGE (BIOTYPE 3) IN RICE (Oryza sativa L.)” Degree : MASTER OF SCIENCE IN AGRICULTURE Faculty : AGRICULTURE Discipline : GENETICS AND PLANT BREEDING Major Advisor : Dr. J. SURESH University : PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY Year of submission : 2023 grains per panicle, 1000-grains weight, grain yield per plant, head rice recovery, kernel length, kernel breadth and kernel L/B indicated that these traits were controlled by additive genes and can be further improved by following simple selection procedure The genetic divergence was high among the 42 rice genotypes and was grouped into seven different clusters. Kernel breadth, plant height and kernel length showed maximum contribution towards genetic divergence. Divergence studies through D2 statistics indicated the presence of substantial diversity by forming large number of clusters with wide range of inter-cluster distances. The highest inter cluster distance was observed between cluster II and VII (418.05) followed by cluster IV and VII (350.95), cluster II and III (298.15) and cluster II and V (281.16). The lowest inter cluster distance was observed between cluster V and VI (54.44). The greater the distance between two clusters, the greater the genetic diversity between the genotypes belonging those clusters. The genotypes belonging to most divergent clusters may exploit the maximum amount of heterosis. High intra cluster distance was observed in cluster III (85.85) followed by cluster II (56.94) and cluster I (55.10) revealing that some genetic divergence still existed among the genotypes of these cluster. Keeping in view, it is concluded that crossing between the genotypes of cluster II and VII, cluster VI and VII, cluster II and III and cluster II and V could results in evolution of desirable transgressive segregants. Based on cluster mean analysis it can be concluded that the genotypes of cluster II can be used in breeding program for generating gall midge resistant lines with less plant height and fine grain nature. Similarly, crosses between genotypes of cluster II and VII could results in development of coarse grain varieties with gall midge resistance. Didianga (Cluster V) with good yield potential can be crossed with lines from diverse groups for generating high yielding lines. The genotypes namely, Didianga (Cluster V), Kakirekkalu (Cluster VI) and Geetanjali (Cluster IV) were found to be good sources for development of lines with good head rice recovery. The percent contribution towards total genetic divergence was greater for kernel breadth (37.39%) followed by plant height (14.52 %) and kernel length (11.03 %). Therefore, these characters should be given importance during hybridization and selection. Character association studies revealed that grain yield per plant exhibited significant and positive association with panicle length, number of grains per panicle, 1000-grains weight, plant height and kernel breadth indicating that the simultaneous selection for these characters could improve the yield. Path coefficient analysis revealed that 1000 grains weight has exhibited the highest positive direct effect on grain yield per plant followed by number of grains per panicle and milling percentage indicating that the selection for these characters was likely to bring about an overall improvement in grain yield per plant directly. Therefore, it is suggested that preference should be given to these characters in the selection programme to isolate superior lines with genetic potentiality for higher yield.EnglishThesis