Phenotypic and Genotypic Mutations in Cowpea Bukal Variety (Vigna unguiculata, Walp) Induced with Gamma Radiation

Abstract

Mutation Breeding through Gamma Irradiation is a potential technique toinduce mutation for crop improvement. The study was done to induce phenotypicandgenotypicvariationsinVignaunguiculatausingradiationdosesexpressedin Grayof the Cobalt60 GammaChamber.Cytogeneticanalysis andirradiationwereconducted in Manilawhile field testing was undertakeninCagayan,Philippines.Chromosomeassay in anaphase cells revealedthat the G1(100Gy)cells exhibited interlocking chromosomes.G2 (150) cells showedparallelchromosomesegments. G3 (200) and G4 (250) cells exuded double bridgesandcriss-crossesofchromosomesegments,respectively.UnderanaphaseI,G5 (300)cellsexhibitedringedchromosomesandbreakagesfromthecentromeres, whileG5 anaphase II showeddouble bridges. Resultsof phenotypic evaluation indicatedthat all the yield-contributing mutants such as heavier pod, longer pod,increasednumber of seeds and greenpods wereconsistently induced bydoses-200,100 and 300 Grays.The most effectivedose to induce desirable traits wasthe200 Gy.Qualitativemutants like pod and seed coat colors weremanifestedinall the samples. The quantitativephenotypic mutants developedin M1 and M2 progenies were all considered beneficial traits and majority of these showedconsiderable improvement in the second mutagenic (M2) generation. Keywords Biochemistry, mutation breeding, gamma radiation, mutation, cytogeneticanalysis, Vigna unguiculata, phenotype, genotype, chromosome assay,Philippines.