TY  - BOOK
AU  - Sindhumole P 
AU  - Manju P (Guide)
TI  - Genetic Analysis for Yield and Resistance to Yellow Vein Mosaic in Okra (Abelmoschus esculentus (L.) Moench)
U1  - 630.28 
PY  - 2003///
CY  - Vellayani
PB  - Department of Plant Breeding and Genetics, College of Agriculture
N2  - The most dreaded disease affecting okra (A belmoschus esulcntus (L.) 
Moench) is yellow vein mosaic (YVM), which affects at all stages of the 
crop growth Being a viral one, the best way to tackle this disease is to use 
resistant varieties Thus it is essential to identify the sources of YVI\1 
resistance and study the inheritance of resistance to develop high yielding 
YVM resistant varieties of okra. Hence an investigation was undertaken to 
reveal the genetic variability and to identify the resistant genotypes in a . 
collection of gerrnplasrn, to estimate the combining ability and heterosis by 
line x tester analysis and to assess the inheritance pattern of YVM 
resistance and yield using generation mean analysis in order to formulate an 
appropriate breeding programme for improving the economic characters. 
Okra germplasm consisting of 101 genotypes was evaluated 
simultaneously for YVM resistance and yield traits as two parallel field 
experiments in RBD with two replications during summer 2000. Screening 
for YVM resistance was carried out at four crop stages vi:., 30 DAS, 50 
DAS, 70 DAS and final harvest. ANOV A revealed significant variation 
among genotypes during all the stages except at 30 DAS. Number of 
susceptible genotypes as well as disease intensity increased gradually from 
30 DAS to final harvest. Four genotypes exhibited high resistance to YVM 
, 
throughout the crop phase. All the genotypes were observed for vector 
population of white fly and leaf hopper in the morning and evening at 30 
DAS, 50 DAS and 70 DAS and they varied significantly for white fly 
population during all the crop stages whereas for leaf hopper count only at 
50 DAS. Morning and evening populations of both vectors at 30 DAS had 
significant association with disease occurrence during 50 DAS to final 
harvest. 
During the evaluation of yield traits ANOV A revealed significant 
variation among the genotypes for the traits vi :., days to first flower, leaf 
axil bearing first flower, leaf area, pollen sterility, fruits planf', average 
 
fruit weight. fruit weight planfl (yield), fruit length, fruit girth, ridges 
fruit I, seeds fruit I, plant duration, crude fibre content, protein content. 
mucilage content, fruit and shoot borer incidence, YVM incidence (except 
at 30 DAS) Besides, colour and pubescence of fruits also were scored for 
each genotype. 
The maximum values of both phenotypic and genotypic coefficients 
of variation were noticed for protein content and fruit yield. Most of the 
traits possessed high heritability especially fruits plant". fruit yield and 
ridges fruifl. High genetic advance (% mean) could be noticed for majority 
of the traits, the highest being for protein content and fruit yield. 
Correlation analysis indicated that most of the character 
combinations had higher genotypic correlation coefficients than phenotypic, 
though both had the same direction. Fruit yield displayed positive 
genotypic association with leaf area, fruits plant", average fruit weight. 
fruit length, fruit girth, seeds fruirl, plant duration and protein content and 
negative correlation with days to first flower, pollen sterility and incidence 
of fruit and shoot borer and YVM (except at 50 DAS). 
Among the thirteen component traits which had high association 
with fruit yield the maximum positive and negative direct effects were 
exerted by plant duration and days to first flower respectively. Maximum 
indirect effects were exerted by fruits planrl in positive direction and by 
leaf axil bearing first flower in negative direction and both these were 
through days to first flower. 
Selection indices were computed utilising yield and its thirteen 
components and eight genotypes were chosen. Among these, five high 
yielding but YVM susceptible types viz, NBPGRI TCR-2020 (LI), 
N BPGR/TCR-1498 (L2), NBPGR/TCR-20 19 (L1), MDU-I (L.j) and 
NBPGR/TCR-985 (Le) were used as lines and NBPGRlTCR-2060 (T I), 
Parbhani Kranti (T 2) and Varsha Uphar (T 1) were used as testers for 
crossing programme. 
 
During line x tester programme, high values of KCO and SClI effects 
were noticed for fruit yield and leaf area. L~ was the most superior line 
which excelled with respect to mean performance and general combining 
ability for yield average weight and length of fruits and leaf axil bearing 
first tlower along with low YVM incidence. Among the testers T 2 was the 
best being superior for yield, number, average weight. girth and ridges of 
fruits 
Out of the fifteen hybrids, overall performance with respect to per 
SI! performance, standard heterosis and sea effects was superior for L2 x T, 
(NBPGR/TCR-1498 x NBPGR/TCR-2060) with respect to days to first 
tlower, leaf area, pollen sterility, fruits plant", average fruit weight, fruit 
weight plant ", fruit length, fruit girth, seeds fruit" and YVM resistance. 
Other excellent hybrids were L5 x T2 (NBPGR/TCR-985 x Parbhani Kranti) 
.J 
L~ x T 2 (NBPGR/TCR-20 19 x Parbhani Kranti) and L, x T, (MDU-I x 
Varsha Uphar) 
These four selected crosses were utilised for generation mean 
analysis in order to detect the gene action with regard to 22 traits including 
incidence of leaf roller and leaf spot. Presence of epistasis was tested and 
subsequently interaction effects vi :., additive x additive, additive x 
dominance and dominance x dominance effects were computed Duplicate 
epistasis was more prevalent than complementary in majority of the cases. 
Predominance of additive and additive x dominance interaction in 
cross L2 x T, for yield and average fruit weight suggests its suitability for 
direct selection and recombination breeding. Cross L5 x T 2 could be utilised 
for heterosis breeding and selection, directly or in segregating generations, 
in order to improve yield, average fruit weight and YVM resistance owing 
to the prevalence of dominance and additive x additive components. The 
gene effects were absent, non-significant or undesirable in cross L, x 
T 2YVM resistance in L, x T., could be improved through heterosis 
breeding, direct selection and recombination breeding due to the presence 
of negatively significant dominance and additive x additive components 


UR  - http://krishikosh.egranth.ac.in/handle/1/5810015030
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