GENETIC ANALYSIS AND IDENTIFICATION OF GENOTYPES WITH NOVEL SOURCES OF RESISTANCE FOR GALL MIDGE (Biotype 3) IN RICE (Oryza sativa L.)
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Date
2023-03-25
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PROFFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY
Abstract
In 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.