Ethylene is a gaseous plant hormone that regulates both growth and senescence, playing diverse roles in plant physiology.
Physiological Effects of Ethylene
1. Effects on Fruit Ripening:
Ethylene accelerates the ripening process in climacteric fruits like bananas and tomatoes by enhancing enzyme activity and color changes.
2. Effect on Abscission:
Ethylene promotes leaf, flower, and fruit drop by weakening cell walls in the abscission zone.
3. Effect on Epinasty:
It causes downward curling of leaves (epinasty) by stimulating differential growth rates in the upper and lower leaf petiole regions.
4. Effect on Seedlings Growth:
Ethylene inhibits stem elongation and promotes radial swelling in seedlings, aiding in their adaptation to environmental stress.
5. Hook Opening:
In dicot seedlings, ethylene helps in the opening of the apical hook by regulating asymmetric cell elongation.
6. Effect on Seed and Bud Dormancy:
Ethylene can break seed and bud dormancy by enhancing enzymatic activities necessary for germination and growth.
7. Growth Promotion – Stem Elongation:
In certain plants, ethylene promotes stem elongation, especially under submerged conditions.
8. Induction of Roots:
Ethylene stimulates the formation of adventitious and lateral roots, enhancing plant stability and nutrient absorption.
9. Flowering:
Ethylene induces flowering in some species like pineapple and mango, acting as a signal for floral initiation.
10. Flower and Leaf Senescence:
Ethylene accelerates the aging process in flowers and leaves by promoting cell degradation and nutrient recycling.
Applications of Ethylene in Agriculture
Fruit Ripening: Used commercially for uniform ripening of fruits like bananas and tomatoes.
Flower Synchronization: Ethylene promotes synchronized flowering in crops like pineapples.
Leaf Drop Control: Ethylene inhibitors are used to prevent premature leaf and fruit drop.
Rooting Agents: Stimulates root formation in cuttings for propagation.
Ethylene's dual role as a growth promoter and inhibitor makes it essential for managing crop yield and quality in agriculture.