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Question
The role of ethylene and abscisic acid is both positive and negative. Justify the statement.
Solution
Positive roles of ethylene: Influences of ethylene on plants include horizontal growth of seedlings, swelling of the axis and apical hook formation in dicot seedlings. Ethylene breaks seed and bud dormancy, initiates germination in peanut seeds and sprouting of potato tubers.
- Negative roles of ethylene: Ethylene promotes senescence and abscission of plant organs especially leaves and flowers.
- Positive roles of abscisic acid: ABA plays an important role in seed development and maturation.
- Negative roles of abscisic acid: It acts as a general plant growth inhibitor and an inhibitor of plant metabolism. ABA inhibits seed germination. ABA stimulates the closure of stomata in the epidermis and increases the tolerance of plants to various kinds of stresses.
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