Stress tolerance indices reveal variation among local maize (Zea mays L.) genotypes under polyethylene microplastic...

Microplastic contamination in agricultural soils may threaten maize productivity and genotype-dependent resilience. This study evaluated the responses of three local maize genotypes, Sukmaraga, Elos, and Duko, to polyethylene (PE) microplastic contamination and compared their relative tolerance under controlled conditions. The genotypes were grown under four PE levels, namely 0, 0.5, 1.0, and 1.5% (w/w). Plant growth, biomass, root elemental concentration, antioxidant enzyme activity, and fresh dehusked ear weight-based tolerance indices were assessed to compare genotype performance under PE stress. Increasing PE levels reduced growth and biomass in all genotypes, with the strongest decline observed in Duko at the highest PE concentration. Root carbon and nitrogen concentrations remained comparatively stable in Sukmaraga and Elos but decreased in Duko under moderate to high PE levels, accompanied by stronger antioxidant enzyme induction. Tolerance indices further differentiated genotype performance, with Elos showing the highest mean productivity (MP = 120.40) and stress tolerance index (STI = 1.08) at 1.5% PE, whereas Duko showed the highest tolerance index (TOL = 6.09) and the lowest STI (0.87). Overall, the results indicate genotype-dependent variation in maize response to PE contamination and identify Elos as the most promising genotype within the tested set under the experimental conditions. These findings provide an initial comparative screening framework for evaluating local maize responses to PE microplastic stress.