Ethylene

• Ethylene is synthesised in large amounts by tissues undergoing senescence and ripening fruits
• Influences of ethylene on plants include horizontal growth of seedlings, swelling of the axis and apical hook formation in dicot seedlings
• Ethylene promotes senescence and abscission of plant organs especially of leaves and flowers
• Ethylene is highly effective in fruit ripening
• Ethylene enhances the respiration rate during ripening of the fruits. This rise in rate of respiration is called respiratory climactic
• Ethylene breaks seed and bud dormancy, initiates germination in peanut seeds, sprouting of potato tubers
• Ethylene promotes rapid internode/petiole elongation in deep water rice plants
• Ethylene helps leaves/upper parts of the shoot to remain above water
• Ethylene promotes root growth and root hair formation, thus helping the plants to increase their absorption surface
• Ethylene is used to initiate flowering and for synchronising fruit-set in pineapples
• The most widely used compound as source of ethylene is ethephon. Ethephon in an aqueous solution is readily absorbed and transported within the plant and releases ethylene slowly
• Ethephon hastens fruit ripening in tomatoes and apples and accelerates abscission in flowers and fruits (thinning of cotton, cherry, walnut)
• Ethephon promotes female flowers in cucumbers thereby increasing the yield