Genetic study of extra-early maturity in cowpea (Vigna unguiculata(L.) Walp.)
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KWAME NKRUMAH UNIVERSITY OF SCIENCE AND TECHNOLOGY,
KUMASI SCHOOL OF GRADUATE STUDIES
DEPARTMENT OF CROP AND SOIL SCIENCES
GENETIC STUDY OF EXTRA-EARLY MATURITY IN COWPEA (Vigna unguiculata (L.)WALP.) EMMANUEL YAW OWUSU
BSc. (HONS) AGRICULTURE TECHNOLOGY
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Abstract
Three field experiments were conducted to investigate the genetic basis of extra-early
maturity in cowpea by incorporating extra-early maturity genes from a land race (Sanzi)
into locally adapted improved medium maturity cultivar (Padi-Tuya). Ten progenies
derived from the cross were evaluated using RCBD with three replications. The
genotypes showed highly significant (p<0.01) variability for days to 50% flowering,
days to first flower initiation, days to 90% pod maturity and days to first pod maturity.
No significant differences (p>0.05) were observed in F
1 and RF
1
progenies suggesting
the absence of maternal effect on the inheritance of extra-early maturity in cowpea.
Broad sense heritability varied from 75% to 99% while narrow sense heritability was
74% to 99%, indicating the importance of both additive and non additive variances
implying that selection for improvement in the F
2
will be effective in improving early
maturity in cowpea. The observed ratio (3:1) for F2 and BC1
indicating the inheritance of
extra-early maturity in cowpea is dominant or partial dominant over late maturity and
therefore influenced by monogenic dominance and recessive epistasis. Negative
heterosis over mid-parent observed for early maturity parameters indicates the
inheritance of early maturity was towards the extra-early parent (Sanzi). The additive-dominance model revealed that both additive and non-additive gene effects contributed
significantly to the inheritance of the trait studied suggesting the potential for further improvement through hybridization and selection procedures. Seed coat colour pattern was maternally inherited and various segregation colour patterns were observed in the F2 and RF2 . The seed coat colour colour pattern observed in the segregation populations
could not fit in any of the modification in Medelian ratios suggesting the trait is
quantitatively inherited.
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A thesis submitted to the School of Graduate Studies, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements for the award of the Degree of Master of Philosophy in Agronomy (Plant Breeding), 2015