HETEROSIS, COMBINING ABILITY AND GENETIC ARCHITECTURE IN COWPEA {Vigna unguiculata (L.) Walp.]2036
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Date
2015-07
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JAU, JUNAGADH
Abstract
An experiment was conducted in a randomized block design with three replications at Instructional Farm, Junagadh Agricultural University, Junagadh during summer, 2014 with a view to estimate heterosis, inbreeding depression, combining ability and nature of gene action involved in the inheritance of seed yield and its components traits in cowpea [Vigna unguiculata (L.) Walp.]. For this purpose using diallel mating design (excluding reciprocals) involving ten different genotypes in Fj and F2 generations.
The analysis of variance revealed that significant difference among the parents except for harvest index in both Fi's and Fa's generations indicating substantial amount of genetic variability among the parents for the characters studied. For parents versus Fi's were also found significant for seed yield and its components traits, except for days to maturity and protein content. This indicated substantial amount of heterosis in cross combinations and Fi's vs Fa's revealed that the Ffs differed significantly from their Fa's for all the characters, except for number of pods per cluster and pod length suggesting presence of considerable amount of inbreeding depression in Fa generation.
The cross combination GC 2 x GC 5 exhibited highest significant and positive heterobeltiosis and high standard heterosis along with low magnitude of inbreeding depression followed by GC 4 x Pant Lobia 2, RC 101 x GC 1, KM 5 x GC 1, IT 38956 1 x KM 5 and IT 38956 1 x GC 5 indicated that these crosses may be exploited for development of high yielding stable lines. The cross Pusa Phalguni x GC 2 exhibited high significant and positive heterobeltiosis and standard heterosis along with high magnitude of inbreeding depression followed by GC 2 x Pant Lobia 1, GC 4 x Pant Lobia 1, Pusa Phalguni x Pant Lobia 1, Pusa Phalguni x Pant Lobia 2, RC 101 x Pant Lobia 2, RC 101 x Pant Lobia 1 and GC 1 x GC 4 suggested that these crosses could be suitable to get better transgressive segregants in segregating generations.
The estimate of variance components due to general and specific combining ability indicated that non-additive gene action played an important role in the expression of all the characters.
Estimates of gca effects indicated that the parents, IT 38956 1 and RC 101 were observed to be the best general combiners for seed yield per plant along with branches per plant and number of pods per plant in both generations. Likewise other parents were also good general combiner for particular yield attributing traits.