Identification of morphological traits affecting high seed yield potential from new hemp germplasm collected in Thailand

Hemp (Cannabis sativa L.) seeds, used as raw materials in the food and cosmetic industries globally, require high seed-producing varieties, as most developed ones focus on medical purposes.This study identified morphological traits affecting high seed yield in local hemp accessions collected from 63 locations across 11 districts in three northern Thailand provinces.The 37 surviving accessions were evaluated, clustered based on morphological data, and compared with hemp varieties RPF1 and RPF2.Cluster analysis classified these into five clusters, with Cluster 1 having the highest seed weight per plant (840.68 g) and longest inflorescence (11.25 cm).First-year correlation analysis revealed a significant positive relationship (p 0.01) between seed weight per plant and inflorescence length (0.50) and stem diameter (0.46).In the second year, the number of flowers per inflorescence significantly correlated with seed weight per plant (0.55).Path coefficient analysis showed a high direct effect on seed yield from inflorescence length (0.37) and stem diameter (0.32) in the first year and branch length (0.80), height (0.73), and number of flowers per inflorescence (0.72) in the second year.Moreover, 24 hemp lines from the second year with seed yield potential were selected for the hemp breeding program.Morphological traits directly affecting seed yield can be used as selection criteria in the hemp breeding programs.