During　rice　threshing,　stems　are　easily　broken　and　usually　mixed　with　the　grains,　making　it　difficult　for　further　automatic　processing.　Thus,　in　order　to　improve　the　efficiency　of　grain　cleaning　during　harvesting,　it　is　beneficial　to　reduce　the　breakages　of　rice　stems.　The　threshold　values　of　rice　stalks　in　both　the　transverse　and　longitudinal　directions　under　tension,　compression　and　bending　forces　were　studied.　Based　on　the　real　time　threshing　loads　that　occur　during　threshing,　the　breaking　paths　of　the　rice　stalks　were　determined　by　applying　combined　loading　tests　and　fracture　mechanisms　proposed.　When　subjected　to　single　load,　rice　stalk　is　a　hard　material　to　break.　Tension　fracture　is　the　major　failure　mechanism　of　the　rice　internodes　that　are　wrapped　with　leaf　sheath.　Combinations　of　bending　&　tension　or　compression　&　tension　can　easily　break　a　complete　rice　stalk　or　even　a　cluster　of　rice　straws.　Therefore,　breaking　paths　of　rice　stalks　during　threshing　include　the　rice　stem　internodes　(with　leaf　sheath)　are　easily　fractured　under　the　coupling　of　threepoint　bending　and　tension;　the　stem　cores　are　broken　under　compression　and　tension,　but　the　stem　nodes　are　brittle　and　susceptible　to　initial　damage　caused　by　bending　or　compression.　These　findings　can　help　facilitate　design　of　the　combine　harvesters　by　assisting　with　the　design　of　mechanisms　that　can　reduce　rice　stem　breakages　during　threshing　and　improve　grain　stalk　separation.　?　2021　IAgrE.　Published　by　Elsevier　Ltd.　All　rights　reserved.