Isolation of Mutants for Grain Yield, Photosynthetic Efficiency and Bundle Sheath Arrangement in Proso Millet ( <scp> <i>Panicum miliaceum</i> </scp> L.)

ABSTRACT Proso millet is a climate‐smart alternative food crop for the future because of its drought and high‐temperature resilience. This study aimed to develop improved lines with higher photosynthetic efficiency and grain yield and understand the interrelationships of photosynthesis and grain yield contributing traits. The gamma and ethyl methanesulfonate (EMS)‐induced mutant population was developed using an elite proso millet variety ATL 1. Mutants were subjected to targeted selection in M 2 and M 3 generations and further evaluated in the M 4 generation based on biometrical, photosynthetic and physiological traits. Eight stable mutants with high photosynthetic efficiency and grain yield were identified in the M 4 generation. Overall, the photosynthetic rate, grain yield and fodder yield of these mutants were increased up to 1.4, 4.4 and 4.9 times, respectively, compared to the wild type. The traits leaf breadth, grain yield, stomatal conductance and transpiration rate exhibited highly significant positive correlations with photosynthetic rate both in M 3 and M 4 generations. Likewise, leaf length, panicle length, number of tillers, fodder yield and photosynthetic rate showed highly significant positive associations with grain yield in both generations. The ultrastructural analysis of contrasting mutants for photosynthetic efficiency (ATL_ lp vs. ATL_ hp ) showed striking differences in the Kranz anatomy, particularly bundle sheath number. The stable mutants identified can be utilised for direct varietal release or as donors in crop improvement programmes. The mutants ATL_ lp and ATL_ hp that have altered bundle sheath arrangement can be utilised for functional genomic studies to explore the C 4 photosynthetic system in this crop.