Role of abscisic acid in plants.

1. ABSCISIC ACID

2. ORIGIN:
 In 1963,ABA was first identified and characterized by
frederick addicott and his associaters.
 They were studying compounds responsible for
abscission of fruits (cotton).
 Two compounds were isolated and called abscisin I and
abscisin II is presently called abscsic acid.

3. INTRODUCTION
 ABA is an inhibitory hormone in plants that
helps a plant adapt to stress.
 ABA mainly occours in plants , leaves,
green fruits, stem, rhizome, tuber, bulb and
in the roots.
 This hormone is produced when roots are
under stress and produce in terminal buds.

4. FUNCTION
 Inhibits shoots growth (not root).
 General growth inhibitors.
 Produce in response to stress.
 Causes stomatal closing and opening.

5. CONTD….
 Prolongation of dormancy.
 Induces seed to synthesis storage protein.
 Inhibits growth in response to changes in
temperature and season.
 Abscission promotion

6. EFFECTS OF ABA
 Slow growth.
 Seed dormancy.
 Drought tolerance.

7. COMMERCIAL USE OF ABA
1. Antitranspirant: It conserve water and reduce the
requirement of irrigation. Photosynthesis is
reduce to a lesser extent( transpiration 56% :
photosynthesis 14%).
2. Flowering: It is useful in introducing flowering in
some short day plants kept under unfavourable
photoperiods.

8. CONTD….
3. Rooting: Use of ABA promotes rooting in many
stem cutting.
4. Dormancy: ABA can be used in prolonging
dormancy of buds, storage organs and seeds.