Electron beam effects and determination of GR50 dose in tropical field corn

Abstract

The maize improvement aimed at enhancing its productivity to feed the increasing world population and is largely dependent on genetic variability present in the breeding material. In the present study, additional genetic variation was induced by a physical mutagen, electron beam (EB). The experiments were conducted for determining the best dose for a 50 per cent reduction in growth (GR 50). The seeds of maize inbred line, PML 93, treated with 10 different doses (50 Gy, 100 Gy, 150 Gy, 200 Gy, 250 Gy, 300 Gy, 400 Gy, 500 Gy, 600 Gy, and 700 Gy) of EB, were tested for seedling growth parameters using pot culture method. Data on various seedling growth parameters such as per cent germination, seedling length, root length, fresh and dry weight, vigor index I and II were recorded. Significant variation was found among the treatments and 200 Gy of the electron beam was identified as the best GR 50 dose for the inbred line PML 93. The cellulase and pectolyase enzymes were deployed for the root tip cell wall digestion and karyotyping was performed to understand the effect of mutation EB doses on chromosomes. Compared to control, the mutagens with a dose of 200 Gy, induced chromosomal breakage at one or two places. These aberrations may lead to heritable variations that can be used for crop improvement in the future.