Anatomical Adaptations and Metal Sequestration Strategies for Improved Yield Stability and Stress Tolerance in Wheat Cultivars Under Heavy Metal Contamination

Abstract

Heavy metal contamination from industrial activities threatens global food security by causing phytotoxic effects in crops like wheat. This study examines the impact of heavy metals (As, Cd, Cr, Ni, and Pb) on the physiological, anatomical, and agronomic traits of two wheat cultivars, Pak-13 and SKD-1, through hydroponic and field experiments. In the hydroponic experiment, plants were grown for 21 days in metal-contaminated solutions. Anatomical studies revealed significant changes under heavy metal stress, such as increased thickness of the root endodermis, xylem, cortex, and stellar cells. Cd exposure caused enlarged parenchyma in Pak-13, while Ni and Pb led to cortical dissolutions in SKD-1. Both cultivars showed thickening of leaf tissues under metal exposure, with SKD-1 displaying better structural adaptations. In the field experiment, agronomic results indicated significant reductions in grain yield (GY) under heavy metal stress. Pak-13 experienced GY reductions of 60.94% (Cd), 91.96% (Ni), 62.68% (Cr), 27.45% (As), and 92.62% (Pb), while SKD-1 showed declines of 2.40% (Cd), 77.48% (Ni), 66.83% (Cr), and 86.76% (Pb). The field data also highlighted a decrease in traits such as tillers per plant (T/P) and spike length per spike (SL/S) for Pak-13, whereas SKD-1 exhibited increased grain yield under As stress and enhanced biomass yield under Cd, Ni, and Pb stress, reflecting better tolerance. This study highlights the importance of anatomical adaptations in understanding metal stress tolerance, with SKD-1 proving more resilient. These findings are essential for breeding wheat cultivars with enhanced tolerance to metal toxicity, contributing to sustainable agriculture in contaminated areas.