Try to clamp it together as much as you can without smashing it...I use folder clamps...
Then wrap with plastic tape, the strechy kind.. You may have seen it in stores, it's used for marking by surveyors and other purposes. Used this method last year following thunderstorms and down bursts which broke down several plants, and it worked great. It will eventually stick back together but will never regain its previous strength. I have not used duck tape but would be afraid it would not allow plant stem to expand as it grows.
Good Luck