Received: 15 Jul 2020 Accepted: 28 Aug 2020 Revised: 28 Aug 2020 https://doi.org/10.37992/2020.1103.132 Vol 11(3):803-808 803 Electronic Journal of Plant Breeding Research Article Efciency and efectiveness of physical and chemical mutagens in cowpea (Vigna ungiculata (L.)Walp) S. Priyadharshni 1* , S. Saravanan 1 , K. Elanchezyan 2 , A. Kavitha Pushpam 3 and M. Arumugam Pillai 1 1 Department of Plant Breeding and Genetics, 2 Department of Agrl. Entomology, 3 Department of Soil Science and Agrl. Chemistry,Agricultural College and Research Institute, Killikulam. 1* E-Mail:priyadharshnis13697@gmail.com Abstract A study was conducted in cowpea (Vigna ungiculata) varieties, VBN 3 and CO(CP) 7 to fnd the efciency and efectiveness of physical (Gamma rays and Electron beam) and chemical (EMS) mutagens. A wide range of chlorophyll mutants and viable mutants were observed in the feld. Overall chlorophyll mutant and viable mutant frequency was higher in EMS treatments in both the varieties. Mutagenic efciency and efectiveness was also found to be higher in EMS treatments followed by electron beam and gamma rays. Mutagenic efectiveness and efciency decreased with increase in doses of all mutagenic treatments. Key words Cowpea, Mutagenic efciency, Efectiveness, Gamma ray, Electron beam, EMS IntRoductIon Cowpea (Vigna ungiculata) is a dicotyledonous pulse crop which belongs to the genus Vigna, section catiang, species Ungiculata and comprises of four sub species viz., unguiculata, dekindtiana, stenophylla and tenuis. The cultivar group Unguiculata is the most diverse of the four and is widely grown in Africa, Asia and Latin America. Cowpea is a multipurpose legume, which is used as green fodder, pulse, green vegetable and green manure. Cowpea is now widely distributed throughout the tropics and subtropics. However, the production of cowpea is limited by both abiotic and biotic constraints. Insect pests are the major biotic limiting factors for cowpea production. The legume pod borer Maruca vitrata Fab. (Lepidoptera: Crambidae), one of the most devastating insect pests of cowpea, which can cause typical yield losses ranging from 20 to 80% (Atachi et al., 2007). So, Genotypes which are naturally resistance to all stress conditions proved to be an efective option in increasing the productivity of pulses without increasing the cost of cultivation of the crop. The fact that pulses are self-pollinated has led to a narrow genetic diversity in many of these crops. In order to expand the genetic diversity mutation proves to be an excellent tool in inducing variability among the cultivars thus increasing the selection efciency and help in isolating the desired mutants for a specifc trait of interest. Various mutagens may be employed to induce the desired mutants, which will be screened and evaluated at the later generations. The efciency and efectiveness of various mutagens are estimated in M 2 generation which portrays the frequency of mutations induced by a unit dose of mutagen and the proportion of mutation in relation to biological damage induced respectively (Molosiwa et al 2016). MAtEriALS And MEthodS The cowpea variety seeds of VBN 3 were obtained from National Pulse Research Centre, Vamban and CO(CP) 7 were obtained from Department of Pulses, Tamil Nadu Agricultural University. These seeds were free from pathogen and insect infestations. The moisture content of the seed was around 12- 14%, which is optimum for