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Principles of Grafting and Budding

Principles of Grafting and Budding. Chapter 11. Grafting & Budding Terms. Graft: Two living plants connected and growing as one. Scion: Dormant shoot, upper portion of graft. Stock: Lower portion of graft, root system. Grafting & Budding Terms.

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Principles of Grafting and Budding

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  1. Principles of Grafting and Budding Chapter 11

  2. Grafting & Budding Terms Graft: Two living plants connected and growing as one Scion: Dormant shoot, upper portion of graft Stock: Lower portion of graft, root system

  3. Grafting & Budding Terms Bud: Similar to graft, but scion is reduced to a single bud

  4. Grafting & Budding Terms Interstock: A middle or intermediate stem piece located between scion & stock

  5. Grafting & Budding Terms Vascular Cambium X P Vascular Cambium: Meristematic tissue between xylem & phloem

  6. Grafting and Budding • Perpetuate clones • Rootstock effects • Changing cultivars • Rapid maturity • Shortens juvenility • Used for breeding programs • Special growth forms • Damage repair • Studying viruses

  7. Seedling Rootstocks • Simple • Cheap • Disease free • Better root systems • Genetic variation

  8. Clonal Rootstocks • Source • Stool beds • Cuttings • Tissue Culture • Characteristics • Uniformity • Disease Resistance • Growth Habit • Flowering Habit • Scion rooting • Disease potential

  9. Rootstock benefits • Disease resistance • Soil tolerance • Size control • Fruit quality Interstock benefits • Overcome incompatibility • Add additional attributes • Dwarfing

  10. Topworking • Change cultivars • Add pollinators

  11. Topworking • Multiple varieties on one tree

  12. Formation of graft union • Line up vascular cambium • Wound healing response • Necrotic plate • Callus bridge formation • Cambium formation • Vascular tissue formation

  13. 1. Close Vascular Contact • 55-90F • Active cambium • High humidity • Pathogen free • Mechanical support • Cambium ‘matching’

  14. 2. Formation of Necrotic plate • Cells killed when cut is made

  15. 3. Callus Bridge Formation • Production & Interlocking of parenchyma • Comes from phloem and immature xylem • Stock produces most callus

  16. 4. New Cambium Formation • Adjacent callus differentiates to form cambium • Cambium forms across bridge of callus tissue

  17. 5. New Vascular Tissue (X&P) From New Cambium • Vascular system must be in place before bud break

  18. GRAFT FORMATION

  19. BUD FORMATION

  20. Factors of graft healing • Incompatibility • Species or variety (cultivar) • Temperature • Moisture • Oxygen • Growth status (active vs. dormant) • Technique or type of graft • Disease situation

  21. Polarity in grafting • Distal and Proximal ends • Reversed polarity works only for a limited time with grafts • Nurse-root grafting • Buds can be reversed • Can cause a wide crotch angle as it grows - strong

  22. Limits of grafting • Generally limited to dicots & gymnosperms • More closely related the better • Permanent grafts in monocots are not successful • Likely has a lot to do with cambium and vascular tissue production • Common between same species • Apple on apple • Harder between different Genera in same family • Tomato on potato (Solanaceae family, or Nightshade) • Rare between families

  23. Symptoms of Incompatibility • High failure rate • Yellow foliage, early defoliation • Premature death of scion • Differences in growth rate • Not always a sign of incompatibility • Can be differences in genetic potential for growth rate • Overgrowths • Breaks at graft union

  24. Types of Incompatibility • Localized • At site of graft contact • Translocated • Substances moved from the scion to rootstock or vice-versa • Virus present

  25. Incompatibility • Cause: Genetic • Mechanism (example theories): • Chemicals found in one partner may be toxic to the other (Cyanogenic glucoside) • Lignification of cell walls may be inhibited

  26. Effects of Rootstocks on the Scion • Size and growth habit • Fruiting • Size, quality, and maturity of fruit • Winter hardiness • Disease resistance • Timing of fruit maturity Effects of Scion on the Rootstock • Vigor • Cold-hardiness

  27. Effects of Interstock on Stock & Scion • Reduces stock and scion size • Direct effect, not indirect Mechanisms of effects (theory) • Translocation (stem) • Absorbing ability (root system) • Interaction of all parts

  28. Factors influencing growth of grafted plants • Nutrition • Translocation • Endogenous growth factors

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