ratio panicle weight grain yield trait average grain weight grain weight to panicle weight ratio A grain yield trait (TO:0000396) which is the ratio of grain weight (TO:0000919) to panicle weight (TO:0000014). plant_trait_ontology TO_GIT:242 TO:0020002 Grain weight (TO:0000919) is a general parent term, covering the weights of various types of caryopsis fruits (PO:0030104), and doesn't specify if they are hulled or dehulled.