Exploitation of Mutagenesis and Selection for the Genetic and Agronomic Imporvement of Oleiferous Brassica

Abstract

Studies were conducted to induce genetic variability in 3 different cultivars of oleiferous brassica by using physical (gamma rays) and chemical (ethyl methane sulfonate: EMS) mutagens for the selection of new genotypes with desired agronomic traits. The radio-sensitivity studies indicated that the LD50 values for Toria Section-A, S-9 and Westar were 1.12, 1.08 and 1.22 kGy of gamma rays respectively. The chemo-sensitivity studies revealed the LD50 values for the above mentioned 3 cultivars were 0.85, 0.88 and 0.83% of EMS respectively. All the varieties showed varied response to physical and chemical mutagens. Stimulatory effects were recorded for some traits at lower doses/ concentrations of mutagens but, in general, with an increase in dose/concentration of mutagens, there was decrease in mean values of all the traits. However, there was significant reduction in combined treatments of physical and chemical mutagens as compared with these separate/ alone ones. Estimates of genetic parameters indicated the induction of new genetic variability for yield and yield components and aphid tolerance in the mutated population. On the basis of promising performance for desired agronomic traits such as high yield and better oil contents, ten mutants of S-9, 4 of Westar and 3 of Toria Section-A were selected. This indicates that physical and chemical mutagens may induced genetic variability for the selection of new genotypes with improved economic characters.