Abstract
<title>Abstract</title> <p> There is little evidence of heavy metals being used as mutagens to induce genetic variation in crops. This study was conducted to evaluate the relative effectiveness and the cyto-morphological and physiological effects of various doses of heavy metals [Cd(NO <sub>3</sub> ) <sub>2</sub> and Pb(NO <sub>3</sub> ) <sub>2</sub> ] in grain amaranth. A range of morphological and chlorophyll variations was observed in treated populations of two varieties of amaranth. Variable order of chlorophyll mutants were observed in the M <sub>2</sub> generation across both the heavy metals. The mutagenic efficacy and efficiency considerably decreased with increasing concentrations of the mutagens, with the order of mutagenic effectiveness being Pb(NO <sub>3</sub> ) <sub>2</sub> > Cd(NO <sub>3</sub> ) <sub>2</sub> in both the varieties. The yield and yield contributing traits were seen to improve at lower concentrations of the mutagens. Eleven mutant lines exhibiting improved agronomic traits were selected from the 10ppm, 20ppm, and 30ppm concentrations of both mutagens in the M <sub>3</sub> generation. The high heritability estimates and genetic advance (GAM) for agronomic traits in M <sub>3</sub> lines suggest that traits are governed by additive gene action and less affected by environment. The standardized concentrations of heavy metals can serve as a very effective and efficient mutagen in a lesser explored crop like grain amaranth with limited breeding advancements. The genetic and transcriptomic studies are advised between the mutant lines and wild types to identify specific genes associated with altered phenotypes. The large mutagenized populations (M <sub>2</sub> ) can serve as an ideal TILLING populations to decipher the specific genes linked with agronomic traits in grain amaranth. </p>