Hemp seed counting and morphometric analysis method comparison

Abstract The USDA ARS Hemp Germplasm Laboratory recently acquired over 800 hemp accessions ( Cannabis sativa L.). Variation in hemp seed size characteristics is needed to develop quantitative standards to support the transition of hemp grain into a commodity. In this study, seeds from 15 hemp accessions with diverse origins were harvested from field plants and analyzed for seed width, length, 1000‐seed weight, and test weight. Seeds were evaluated using four methods: (1) hand counting, (2) hand counting with manual caliper measurement, (3) automated seed counting, and (4) automated seed counting and measuring with a seed analyzer. Three technical replications of each measurement method were conducted on the same 3.84 mL seed sample. Hand counting was the fastest and least expensive method when counting fewer than 83 seeds. Automated methods could reliably count seed lots in under 74 s and were more repeatable than the manual counting and measuring method. Significant seed size differences were detected between accessions with G 33369, Yun Ma and G 33260, Dakota Sandhills (L) having the largest and smallest seed widths, lengths, areas, and 1000‐seed weights, respectively. When accessions were grouped by origin, East Asian accessions were found to have the largest seed size, and US feral accessions had the smallest seed size. Seed counting and analysis tools can be utilized by plant researchers and germplasm repositories to increase throughput during routine handling while rapidly capturing morphometric data.