Abstract:Chenopodium album, which is widely distributed in arid zone of Xinjiang, produces two distinct types of black and brown morphs of seeds on the same plant. An investigation on heteromorphic seeds of C. album was conducted as the following aspects: the morphology and structure of seeds, effects of seed coat treatment, plant growth hormone and different environmental factors on seed germination, analysis of electrophoresis pattern of isozymes in heteromorphic seeds, and finally the relationship between the mechanism of heteromorphic seeds germination and its adaptation strategies in heterogeneous environments were discussed. Results showed: (1) Black seeds, with a thick and hard testa, were dormant and germinated slowly to a low final percentage, while brown seeds, with a thin and soft testa, were non-dormant and germinated quickly to a high final percentage; (2) Dormancy of black seeds could be completely broken by removal of testa around the radicle; (3) GA3 and ethephon had no significant effect on promoting germination of black seeds; while KNO3 treatment could cause considerable stimulation in germination of black seeds; further co-treatment with ethephon and KNO3 could thoroughly break the dormancy of black seeds; (4) The electrophoresis pattern of isozyme, including esterase, peroxidase and catalase, differed each other between two seed types; (5) Compared with brown seeds, germination of black seeds was light-sensitive; dry storage at low temperature had no significant effect on germination of both black and brown seeds, although germination percentage of black seeds fluctuated slightly. Taken together, we concluded preliminarily that dormancy mechanism of black seeds can be attributed to both inner factor (embryo) and outer (seed coat) factor. In all, seed heteromorphism of C. album and its germination mechanism are highly adapted to the harsh and unpredictable environments in arid area of Xinjiang.