Study on seed morphological characteristics and viability determination method in Apocynum spp. and Poacynum spp.

Seed morphological characteristics, 1 000-seed weight, and viability measurement methods were studied using eight genotypes of Apocynum and Poacynum in Allahak Town, Altay City, Xinjiang Uygur Autonomous Region. Results showed that the mean seed length of Apocynum venetum was 2.75 mm, with a width of 0.68 mm and thickness of 0.49 mm. Among the seven Poacynum genotypes, seeds of the genotype with purple spotted medium flowers were longest, with a mean length of 4.51 mm. Seeds of the genotype with green stems and white flowers were widest, with a mean width of 0.90 mm, and seeds of the genotype with green stems and white flowers and P. hendersonii were the thickest (0.61 mm). The length, width, and height of the eight genotype seeds ranged from 2.75 to 4.51 mm, 0.68 to 0.90 mm, and 0.48 to 0.61 mm, respectively. The purple spotted medium flower was the largest genotype and A. venetum was the smallest genotype. 1 000-seed weight ranged from 0.38 to 1.32 g. All genotypes had brown seeds, but P. hendersonii had the deepest color. Seeds of eight genotypes were characterized by non-dormancy seed germination with a short germination time, which could be used to determine the viability quickly. When viability was measured by tetrazolium staining, all tested seeds showed impermeable tetrazolium. The seed coat was cut vertically after a pre-wetting period of 12～14 hours, then cut seeds were dyed for 12 hours. The identification criteria was 80% staining of seed embryos. This experiment mainly carried out the research on the morphological characteristics and viability measurement methods of Apocynum and Poacynum, which can provide a certain basis for the identification of venetum seed viability, large-scale planting, and seed breeding