principles of grafting and budding
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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. - PowerPoint PPT PresentationTRANSCRIPT
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
Bud: Similar to graft, but scion is reduced toa single bud
Grafting & Budding Terms
Interstock: A middle or intermediate stem piece located between scion & stock
Grafting & Budding Terms
Vascular Cambium: Meristematic tissue between xylem & phloem
X P
VascularCambium
Grafting and Budding
• Perpetuate clones
• Rootstock effects
• Changing cultivars
• Rapid maturity– Shortens juvenility
– Used for breeding programs
• Special growth forms
• Damage repair
• Studying viruses
Seedling Rootstocks
+ Simple
+ Cheap
+ Disease free
± Better root systems
– Genetic variation
Clonal Rootstocks
• SourceStool bedsCuttingsTissue Culture
• Characteristics+ Uniformity
+ Disease Resistance
+ Growth Habit
+ Flowering Habit
– Scion rooting
– Disease potential
Rootstock benefits
• Disease resistance
• Soil tolerance
• Size control
• Fruit quality
Interstock benefits
•Overcome incompatibility
•Add additional attributes
•Dwarfing
Topworking
• Change cultivars
• Add pollinators
Topworking
• Multiple varieties on one tree
Formation of graft union
1. Line up vascular cambium
2. Wound healing responsea. Necrotic plate
3. Callus bridge formation
4. Cambium formation
5. Vascular tissue formation
1. Close Vascular Contact
• 55-90F
• Active cambium
• High humidity
• Pathogen free
• Mechanical support
• Cambium ‘matching’
2. Formation of Necrotic plate
• Cells killed when
cut is made
3. Callus Bridge Formation
• Production & Interlocking of parenchyma• Comes from phloem and immature xylem• Stock produces most callus
4. New Cambium Formation
• Adjacent callus differentiates to form cambium
• Cambium forms across bridge of callus tissue
5. New Vascular Tissue (X&P) From New Cambium
• Vascular system must be in place before bud break
GRAFT FORMATION
BUD FORMATION
Factors of graft healing
• Incompatibility
• Species or variety (cultivar)
• Temperature
• Moisture
• Oxygen
• Growth status (active vs. dormant)
• Technique or type of graft
• Disease situation
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
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
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
Types of Incompatibility
• Localized– At site of graft contact
• Translocated– Substances moved from the scion to rootstock or
vice-versa
• Virus present
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
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
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
Factors influencing growth of grafted plants
• Nutrition
• Translocation
• Endogenous growth factors