Effect of Mechanical Stress and Inhibitors of Protein Synthesis on Leaf Epinasty in Mechanically Stressed Poinsettia Plants1

Abstract

Abstract Periodic shaking increased the resistance of potted poinsettia (Euphorbia pulcherrima Klotzsch ex. Willd., cv. Annette Hegg Diva) plants to mechanically induced leaf epinasty, but this resistance was lost within 24 hours of discontinuing the shaking. Bending petioles, not their reorientation in the gravitational field, caused increased ethylene production by excised petioles. Foliar sprays containing 40 μm cycloheximide, which were applied 24 hours before the plants were sleeved for 24 hours, completely prevented mechanically induced leaf epinasty, but were phytotoxic to the bracts.