Generating Novel Morpho‐Phenological Variations Using High‐Energy Pulse Electron Beam Irradiation in Tropical Field Corn ( <scp> <i>Zea mays</i> </scp> L.)

ABSTRACT Tropical field corn, due to its wider adaptability, is the preferred choice for breeders working in South and Southeast Asia. While this crop exhibits considerable natural variability for yield‐attributing traits, the application of mutation breeding provides an additional opportunity to generate novel genetic variations, while maintaining a stable genetic background. To exploit novel genetic variability without significantly altering its genetic constitution, the field corn inbred line AI 544 was irradiated with a high‐energy pulsed electron (HEPE) beam. The mutant population was sequentially advanced through successive generations across two distinct locations and environments, that is, the ICAR‐Indian Agricultural Research Institute, New Delhi, and the IARI‐Regional Research Centre (RRC), Dharwad, Karnataka. The M 3 :M 4 plants were characterized for various morpho‐phenological traits. Based on morpho‐phenological variability, phenotypic diversity and molecular fidelity, a novel plant phenotype, M544‐13, was identified along with other mutants, namely, M544‐32 for high kernel row number, M544‐21 for high kernel per row and M544‐20 for high test weight. These mutants exhibited distinct phenological characteristics when compared to the wild type (AI 544). Karyotypic analysis revealed specific structural chromosomal aberrations in the identified ‘gigas’ mutant, M544‐13 that had large leaf lamina (15 cm), higher seed size (32 g/100 seeds) and robust plant type. These mutants may serve as valuable genetic resource for enhancing yield component traits in tropical maize in general and idiotype breeding in particular. It was evident that the mutagen, HEPE beam, induces heritable changes, which may be effectively targeted for further improving different morphological traits in maize. Further comprehensive studies, including genomic content analysis and sequencing‐based approaches, may elucidate the underlying cause of this mutation.