Growth Regulators in Fruit Production

1. Growth Regulators in Fruit Production www.Hortilover.com

2. Plant Hormones • Organic substances produced in the plant • Translocated within plant • Evokes response at low concentration HORT 319 - Temperate Fruit and Nut Production

3. Action of Hormones are Complex and Poorly Understood • Levels vary with plant tissue and developmental stage • Effective concentrations vary with plant tissue and developmental stage • Do not work alone - relative amounts of hormones are important HORT 319 - Temperate Fruit and Nut Production

4. Effect of Applied Hormones Depend on • Species or cultivar • Organ acted upon • Timing of the spray • Concentration absorbed HORT 319 - Temperate Fruit and Nut Production

5. Effect of Applied Hormones Depend on • Species or cultivar • Parthenocarpic set in pears • Higher NAA needed to thin Golden Delicious vs. Red Delicious • Less vigorous cultivars respond to a greater degree than vigorous trees • Organ acted upon • Timing of the spray • Concentration absorbed HORT 319 - Temperate Fruit and Nut Production

6. Effect of Applied Hormones Depend on • Species or cultivar • Organ acted upon • NAA applied to young fruit cause fruit drop (10-50 ppm) • NAA applied to base of stem cause rooting (20-200 ppm) • Timing of the spray • Concentration absorbed HORT 319 - Temperate Fruit and Nut Production

7. Auxin Concentration Effect on Plant Growth HORT 319 - Temperate Fruit and Nut Production

8. Effect of Applied Hormones Depend on • Species or cultivar • Organ acted upon • Timing of the spray • NAA applied to fruit (10 to 50 ppm) • 20 days after bloom cause fruit drop • 21 days before harvest prevent drop • Concentration absorbed HORT 319 - Temperate Fruit and Nut Production

9. Effect of Applied Hormones Depend on • Species or cultivar • Organ acted upon • Timing of the spray • Concentration absorbed • Concentration applied • Absorption • Environment: Temperature and Moisture • Plant cuticle • Surfactants • pH of water HORT 319 - Temperate Fruit and Nut Production

10. Types of Hormones • Auxins • IBA, NAA, NAD, IAA, 2,4-D • Gibberellins • Cytokinins • BA, kinetin, zeatin, 2ip, TDZ • Ethylene • Ethrel, ethephon • Growth Retardants • SADH, PPP333, others HORT 319 - Temperate Fruit and Nut Production

11. Auxins: • Types • IBA = indolebutyric acid • IAA = indoleacetic acid • NAA = naphthalene acetic acid • NAD = naphthalene acetamide • 2,4-D = 2,4-dichlorophenoxyacetic acid • Natural production • Effects • Examples of use HORT 319 - Temperate Fruit and Nut Production

12. Auxins: • Types • Natural production • Growing shoots and young leaves • Developing embryos • Effects • Examples of use HORT 319 - Temperate Fruit and Nut Production

13. Auxins: • Types • Natural production • Effects • Rate of cell enlargement • Inhibit bud growth • Stimulate cambial cell division • Abscission of fruit • Hasten ripening via ethylene production • Stimulate rooting • Examples of use HORT 319 - Temperate Fruit and Nut Production

14. Auxins: • Types • Natural production • Effects • Examples of use • NAA or NAD @ 5-50 ppm for thinning • NAA to control preharvest drop • NAA @ 1000 ppm to control root sprouts • IBA @ 20-200 to stimulate the rooting of cuttings HORT 319 - Temperate Fruit and Nut Production

15. Gibberellins: GA • Natural production • Very young leaves and embryos • Fruits • Roots • Effects • Stimulate cell elongation • Prevent flower initiation • Prevents abscission in young fruit • Break rest in buds and seeds • Examples of use HORT 319 - Temperate Fruit and Nut Production

16. Gibberellins: • Natural production • Effects • Examples of use • Improve fruit shape in apple (with BA) • Grapes • Increase seedless set • Increase fruit and cluster size • Loosen clusters by pedicel elongation • Delay harvest in cherry • Reduce russetting on Golden Delicious HORT 319 - Temperate Fruit and Nut Production

17. Cytokinins: • Types • BA = benzylamino purine • Kinetin = 6, furfurylamino purine • Zeatin • 2iP = 6-(,-dimethylallylamino) purine • TDZ = thidiazuron • Natural production • Effects • Examples of use HORT 319 - Temperate Fruit and Nut Production

18. Cytokinins: • Natural production • Roots • Young fruits • Effects • Promote cell division • Regulate apical dominance • Promote branching • Enhance fruit bud initiation • Influence translocation • Prevent Abscission/senescence HORT 319 - Temperate Fruit and Nut Production

19. Cytokinins: • Types • Natural production • Effects • Examples of Use • Promalin = BA + GA • Increasing branching in apple (100-200 ppm) • Increase fruit length in Red Delicious apple (25 ppm 10days before full bloom) • Induce shooting in tissue culture HORT 319 - Temperate Fruit and Nut Production

20. Ethylene: • Types • Ethrel and ethephon • Ethylene producing compounds • Natural production • Maturing to ripening fruit • Injured tissue • Effects • Stimulates floral initiation • Promotes abscission • Increase respiration/maturation/coloring of fruit HORT 319 - Temperate Fruit and Nut Production

21. Ethylene: Examples of Use • Increase return bloom • 100-1000 ppm @ early summer • With NAD, thinning and return bloom • 20-200 ppm @ 4-8 weeks after bloom • Delay bloom with sweet cherry • Sept. application • Advance maturity in apple • 250-500 ppm 1-2 weeks before harvest • Induce abscission in apple, cranberry, grapes, nuts • 500-1000 ppm 10 days before harvest HORT 319 - Temperate Fruit and Nut Production

22. Growth Retardants • Alar = SADH = daminozide • Used extensively in apple production • Prevent preharvest drop • Improve color and quality • Control growth • Increase set • Taken off market by EPA in 1985 • Gibberellin biosynthesis inhibitors • PPP333 = Cultar = Bonzai • Not registered in USA for fruit production HORT 319 - Temperate Fruit and Nut Production

23. Common uses of Growth Regulators HORT 319 - Temperate Fruit and Nut Production DAFB=days after full bloom, BH=before harvest, FB=full bloom

24. Any Questions about the use of PGR in fruit production?