Effect of cadmium stress on seed germination and growth of Amaranthus cruentus germplasms from different locations

This study aimed to evaluate and compare the cadmium tolerance of Amaranthus cruentus germplasms from different geographical sources, enrich the phytoremediation species for cadmium-contaminated soil, and provide materials for breeding new cadmium-tolerant A. cruentus varieties. We used 16 A. cruentus varieties as experimental materials and a seed germination experiment to investigate the germination characteristics of A. cruentus seeds under cadmium stress. Membership function and cluster analysis methods were used to comprehensively evaluate the cadmium tolerance of A. cruentus. The results revealed that the 16 varieties showed strong cadmium tolerance at 80 μmol·L⁻¹ cadmium concentration. In addition, the germination potential, germination rate, germ length, and germination index of the control and cadmium-treated seeds were not significantly different for all 16 varieties; however, the radicle length and vigor index were significantly lower in the cadmium-treated seeds than in the control seeds (P < 0.05). Genus analysis revealed that eight germplasms (Ace655, Ace631, Ace628, Ace617, Ace575, Ace650, K472, and K112) were of the cadmium-sensitive type, indicated by < 29% of relative radicle length of most germplasms. Seven germplasms (Ace671, Ace689, Ace568, Ace666, Ace621, Ace651, and Ace613) were of the cadmium-tolerant type, indicated by the relative radicle length of most germplasms between 29% and 35%. Only one germplasm (R104) was extremely cadmium-tolerant, indicated by high values of measured indicators of growth and germination.