Genetic improvement of pyrethrum (Tanacetum cinerariifolium Sch. Bip.) through gamma radiation and selection of high yield stable mutants through seven post-radiation generations

Abstract

Purpose To increase the size of the flowers for easy plucking, flower yield, pyrethrins content (%), and elite mutant selection in pyrethrum. Materials and methods To increase pyrethrum production and acclimatize in north Indian plain condition, a genetic improvement program was undertaken to widen the range of variations for size and yield of flowers and pyrethrins content (%) in pyrethrum crop. Pyrethrum seeds of the variety Avadh were irradiated with gamma rays at 20 to 300 Gy doses in Gamma chamber 5000 (cobalt-60 research irradiator). Results Observations gathered visually in M1 based on vigor, synchronization of flowering, and flower’s size. Out of 90 M2 families, 20 mutants were raised in M3 along with the check-in preliminary evaluation trial. The four promising mutants, 1 (20 Gy-3), 7 (40 Gy-5), 10 (40 Gy-8), 14 (60 Gy19-10) was grown for four years in a bench-scale trial (randomized block design, replicated thrice) to test the yield performance and selection of high yielding elite mutant (s). It has been found that pyrethrum is sensitive to gamma rays irradiation and produced a high range of qualitative and quantitative variations. After massive screening over four years, two promising mutants for high dry flower yield and pyrethrins content, namely 7 (40 Gy-5), and 10 (40GY-8) were isolated. Conclusions The mutagenesis changed traits mean in positive or negative directions. Pyrethrum plant is highly sensitive to gamma irradiation and produced a high range of variability in the qualitative and quantitative traits. The mutagenesis changed the mean of traits in both positive and negative directions. Due to mutagenic efficacy, two mutants 7 (40 Gy-5), and 10 (40GY-8) were expressed high performance for pyrethrin percent i.e., 87.23 and 59.78% improvement over the check variety ‘Avadh’, with synchronous flowering. These two mutants are in the pipeline for release as a variety for cultivation in the North Indian plains.