In Danforth experiments, need to group by cultivar and plant id

[dlebauer]

In Danforth plots, when a single cultivar is selected the lines are discontinuous. There should be one line per replicate pot for each cultivar. For field trials each replicate is defined by a unique site, but at Danforth all plants have the same site. Need to use the unique identifier for each plant (barcode)

Probably need to join the entities table to the traits table and find the barcode stored in entities.name