Auxin can be bioassayed by
(a) Avena coleoptile curvature
(d) lettuce hypocotyl elongation
Auxin is a phytohormone that is often bioassayed by Avena coleoptile curvature test. The angle of curvature of a decapitated oat coleoptile is measured after placing an agar block containing auxin on one side. The ability of auxin to stimulate shoot growth is then measured.