Principles of Fruit Production (Pomology 16201) Chapter 3 ...kenanaonline.com/files/0112/112629/Lecture 4.pdf · Prof. Dr. Atef Mohamed Ibrahim Alexandria University Principles of

Prof. Dr. Atef Mohamed Ibrahim Alexandria University

Principles of Fruit Production (Pomology 16201) Faculty of Agriculture

Second Level Students Pomology Department

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Principles of Fruit Production (Pomology 16201)

Chapter 3

(Fourth lecture)

Grafting or Budding is the art of joining parts of different plants together in such a manner that they will

unite and continue their growth as one plant. The upper portion of the graft combination is termed

Scion, the lower part or root is called Rootstock, Understock or Stock. All methods of joining plants

are properly termed grafting, but when the scion part is only a small piece of bark (and sometimes

wood) containing a single bud, the operation is termed budding, (Fig.2)

Fig. 2

Methods of budding (Fig.3):

a- Shield (T) budding b- Patch budding

c- Chip budding d- Mound layering (See the practical part).




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Chip budding

Fig. 3

Methods of grafting (Figs 4-7):

a- Whip (Tongue) grafting b- Cleft grafting c- Side grafting




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d- Bark grafting e- Approach grafting f- Bridging & Inarching (See the practical part).

Fig. 4




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Fig. 5

Fig. 6- approach grafting




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Fig. 7- Bridging & Inarching

Reasons for Grafting & Budding:

1. Propagating fruit varieties that produce seedless fruits such as Washington Navel Orange and

Common fig …etc.

2. Replacing the undesirable varieties of the established orchards by new desirable ones.

3. Repairing damaged parts of the tree, using Bridge-grafting or inarching.

4. To overcome the incompatibility barrier between the scion and rootstock by sing compatible

interstock (Double grafting).

5. To overcome some pests:

a. Many Citrus species are very susceptible to Gummosis, if they grow on their own roots. To avoid

this problem, they should be grafted onto tolerant rootstocks such as Sour orange or Cleopatra

mandarin.

b. Roots of the European grapes are easy to be invading by the Phylloxera insect, to overcome this

problem, use the resistant rootstock (American grapes).

c. Peach roots are quite susceptible to the nematode in the Sandy soils. In such soils, resistant

rootstocks as Shlil, Bokhara, Yunan, Nemaguard and Nemared can be used.

d. Roots of Apples, especially Baladi apple are susceptible to Wooly aphids. Therefore, they

should be grafted onto a Northern spy, the resistant rootstock.

6. To overcome the undesirable soil conditions:

a) Almond trees are usually grown in light soils, in loamy soils, so they should be grafted onto

Myrobalan plum.




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b) Almond as well as Peach trees can’t tolerate alkali soils, in such a case, graft them onto Prunus

davidiana, the Chinese peach, which tolerates such soils.

c) Peach tree require light soils, in heavy soils, they should be grafted onto Apricot or Plum

rootstocks.

Grafting Compatibility:

The ability of two different plants grafted together to produce successful union and to develop as one

unit (plant) is termed Compatibility. The opposite, of course, would be Incompatibility. With experience

and observation it was concluded that the union is not fully compatible except between closely related

species of the same genus. However, this observation is not always true and such a conclusion can be

confirmed by the following examples:

1. Plants of different genera are successfully grafted together, for example, Quince (Cydonia

oblonga), has been used as a dwarfing rootstock for some Pears (Pryrus communis). Also,

Quince is used as a rootstock for Loquat (Eriobotrya japonica).

2. Varieties that belong to the same species show variable degrees of compatibility to a given

rootstock; for example, Hardy as well as Shobra Pear varieties are compatible with the Quince,

while Le Conte and Bartlett varieties are incompatible with that rootstock. In grafting the later

ones on Quince, interstocks are usually used. In case of grafting Le Conte on Quince, the

interstock is Shobra, but in grafting Bartlett onto Quince, the interstock is Hardy. This

operation is termed double grafting or Double working, (Fig.8).

Fig. 8

Symptoms of Incompatibility:

1. All incompatible combinations show a weak union.

2. The union when broken is relatively smooth.




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3. Overgrowth at above or below the graft union.( Fig.9 ):

Fig. 9

Effects of the Graft Partners on Each Other:

A – Effect of the rootstock on the scion:

1. Effect on tree size and shape: It was observed that Pear scion grafted onto Quince (a dwarfing

rootstock), produces relatively a smaller canopy than that either growing directly on its own

roots or that grafted onto vigorous stocks. In other words, dwarfing rootstocks reduce the canopy

size.

2. Effect on the bearing time (age): Dwarfing rootstock enforces the top scion to reach the bearing

stage (fruiting age) earlier than that grafted onto a vigorous stock.

3. Effect on fruit quality: It Sweet Orange is budded onto Sour Orange (a rootstock), the produced

fruits are smooth, thin-skinned, juicy with excellent quality and can be stored well without

deterioration. But when Rough Lemon is used, the obtained fruits are often thick-thinned,

somewhat large and coarse, inferior in quality and low in sugar.

4. Effect on diseases transmission: When French Pear varieties (Pyrus communis) grafted onto the

Japanese Pear (Pyrus pyrifolia), physical disorder appear at the calyx end (black end) of the

produced fruits. But if they are grafted onto Pyrus communis, such abnormality would not

appear.

5. Effect on winter-hardiness: A scion if grafted onto a dwarfing rootstock, the top can tolerate cold

much better than that grafted onto a vigorous rootstock, because the dwarfing stock stops the top

growth early. Ceasing growth gives the top the opportunity for the maturation of the new woods

before winter, so they can tolerate its cold.




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B – Effect of the scion on the rootstock:

The effect of the scion on the rootstock is not as pronounced as the effect of the rootstock on the

scion. However, some observations show certain effects of the scion on the rootstock, for example, if a

strongly growing scion variety is grafted on a weak rootstock, the growth of the rootstock will be

stimulated as to become larger than it would have been if left ungrafted. Moreover, characteristics of the

rootstock’s fruits could be altered due to the effect of the scion. It was noticed that fruits could be altered

due to the effect of the scion. It was noticed that fruits of “Tompkin king” an Apple rootstock tended to

possess some characteristics of the scion “McIntoch” fruits.

Time of budding & grafting:

In Citrus, budding is usually done during spring; however, it could be made during fall. As for Mangoes

and Olives, summer is the proper time for budding. Deciduous fruits are commonly budded during

summer or grafted during spring.

Characteristics of a good scion wood:

1. It should be taken from vigorous trees free of diseases.

2. It should be prepared from mature shoots, avoid water sprouts.

3. It should be cut in spring, just before growth starts.

4. Plump and mature buds are the most preferable.

5. The midportion of one-year-old shoot furnishes the best scions, basal as well as tip portions should

be discarded.

Chimera

If an organ (shoot, leaf, fruit, bud…etc.) is composed of two genetically different tissues growing

adjacent to each other, such a case is termed Chimera. (Fig.10)

Types of Chimera:

1 - Sectorial Chimera

A sector of one tissue penetrating to the center of organ.

2 – Periclinal Chimera

A layer of one tissue completely surrounds the entire organ.

3 – Mericlinal Chimera

A section composed of a layer representing one tissue occupies a small area of the organ’s surface.




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Fig. 10

Graft chimera:

In young grafted plant, if the scion is cut back severely, an adventitious bud may sometimes arise from

the callus at the junction of the stock and scion. The resulting shoot is chimera in which, the cells of the

two graft components remain genetically distinct regardless of how intermingled they become.

Rootstocks of the important fruits

1 – Apple:

a) French crab seedling: Introduced from France, and widely used.

b) Paradise & Doucin: Mostly propagated by mound layering.

c) A number of rootstock clones obtained such as:

1) Malling 9 a dwarfing rootstock

2) Malling-Merton (M.M 106) a semi-dwarfing rootstock

3) Malling 111 (M.M.111) a vigorous rootstock.

d) Baladi apple (local variety): Suckers readily propagate it. It is very susceptible to wooly

aphids, an insect causing serious injuries to apple trees via infesting their roots.

e) Northern Spy: It resists wooly aphids.

2 – Pear:

a) Pyrus communis (French Pear): It resists Canker disease which causes serious injuries to tree

trunk. It tolerates high lime levels in the soil. Very susceptible to Fire blight.

b) Pyrus pyrifolia (Japanese Pear): It resists Fire blight. Very susceptible to the physiological

disorder “Black end” or “Hard end” which may occur in certain Pear varieties when they are

grafted onto it.




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c) Pyrus calleryana: It resists Fire blight. Produces vigorous trees with strong graft union. Trees on

it are very susceptible to Canker.

d) Cydonia oblonga (Quince): A dwarfing rootstock. It resists Pear root aphids and Nematodes.

Very susceptible to Oak root fungus, Fire blight and excess lime in soil. It is compatible with

some Pear varieties such as Hardy and Shobra and

3 – Quince: Quince can be grafted onto Quince seedlings.

4 – Peach:

a) Peach seedling: The most satisfactory rootstock, however, their roots are quite susceptible to

nematodes, especially in sandy soils. In growing Peaches in such soils, certain rootstocks

that resist this pest should be used. Among the resistant stocks; Yunan, Bokhara, Shalil,

Nemaguard and Nemared.

b) Apricot seedling: Are occasionally used, but the graft union is not always successful.

c) Prunus davidiana (Chinese Peach): Peach roots can’t tolerate alkali soils, in such soils,

Peaches should be grafted onto Chinese Peach rootstock that tolerates alkali soils.

5 – Plum:

Myrobalan Plum: Is widely used as a rootstock, it is often propagated by seeds.

Marianna Plum: Is commonly propagated by cuttings.

Peach, Almond or Apricot: Are usually used as rootstocks for Plums in light soils.

6 – Almond:

a) Seedlings of bitter and sweet Almonds: The most desirable rootstock, they are compatible with

almost all Almonds and form strong graft union with them. They grow well in sandy soils and

tolerate drought due to deep penetration of their roots in the soil.

b) Peach and Myrobalan Plum: They could be used as rootstock for Almonds; however, they

form weak graft unions.

7 –Persimmon (kaki):

a) Diospyrus lotus: Vigorous and tolerates drought.

b) Diospyrus virginiana: Quite tolerant to excess soil moisture.

8 – Pecan:

a) Carya pecan: Commercially, Pecan varieties are propagated almost entirely on Pecan (Carya

pecan) seedlings. It is compatible with most Pecan varieties, but is sensitive to excess soil

moisture.

b) Carya aquatica: It tolerates excess soil moisture.




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9 – Walnut:

a) Juglans hindsii (North California black walnut): Very vigorous seedlings that make a strong

graft union, but they are susceptible to certain diseases.

b) Juglans californica (Southern California black walnut): A dwarfing rootstock, it makes a

strong graft union with almost all Persian walnut varieties.

c) Juglans regia (Persian walnut): Seedlings of this rootstock produce good trees with an excellent

graft union.

10 – Cherry:

a) Mazard & Mahaleb seedling: The most common stocks. Mazard seedlings are very susceptible to

nematodes.

b) Stockton Morello: Occasionally used, it tolerates heavy soils.

11 -Loquat: Can be grafted onto Loquat or Quince seedlings.

12 – Olive:

a) Shimali seedlings or Clones: Olive varieties could be grafted on this rootstock; however

considerable variations in tree vigor and size may result.

b) Redding: A vigorous rootstock that makes a strong graft union with almost all olive varieties.

13 – Avocado: Seedlings of Fuerte variety are usually used as rootstocks for most Avocado varieties.

14 – Mango:

Certain Mango rootstocks such as Mado, Gadong and Pumella were introduced from India to be used

as new rootstocks.

15 – Citrus:

a) Sour orange:

Good and compatible for all citrus varieties.

Producing large vigorous trees.

It produces fruits of fairly high quality.

It resists Gummosis.

The only defect is its susceptibility to Quick decline.

b) Cleopatra mandarin:

Trees on this rootstock show good yields of high quality.

It resists both Gummosis and Quick decline.

c) Rough lemon:

Well adapted to sandy soils.




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It resists both Gummosis and produces fruits of low quality.

d) Sweet orange:

A good and compatible stock for all citrus species, producing vigorous large trees.

It produces standard-size fruits that are thin-skinned, juicy and fairly high quality.

It is very susceptible to Gummosis.

Not suitable for poorly drained heavy soils.

e) Lime:

A very vigorous rootstock.

It produces a high yield of high-quality fruits.

It suits sandy as well as light loamy soils.

f) Sweet lemon:

The most suitable stock for Yafawi orange variety.

It doesn’t suit soils of high moisture contents.

Very susceptible to Gummosis.

g) Citron:

A dwarfing rootstock.

It is not suitable for sandy soils.

Very susceptible to Gummosis, especially in heavy soils.

h) Troyer citrange:

Very tolerant to Gummosis and Quick decline.

i) Morton citrange:

Tolerates Gummosis and Quick decline.

j) Swingle citromello:

Tolerates Gummosis and Quick decline (tristeza)

Comparative salt, cold and drought justify its greater use.

It can’t tolerate alkali soils.

k) Volkamariana:

A vigorous rootstock.

It can grow well in sandy soils.

Used as rootstock for mandarin, orange and grapefruit.




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The trees that grown onto it produce fruits of large size with thick peel and less juicy pulp with

low acid and sugar contents.

Micro-Propagation (Tissue Culture)

Micro-propagation or tissue culture is the development of new plants in an artificial medium under

aseptic conditions from very small pieces of plants, such as embryos, seeds, stems, shoot tips, root tips,

callus, single cells and pollen grains.

The selected explants (parts) are allowed to grow in special glass tubes containing a particular medium.

This medium should contain water, inorganic elements, vitamins, growth regulators and some other

organic complexes. The planted tubes are kept under suitable temperature and exposed to light for a

specific period of time.

When shoots and roots have developed, the new plantlets are transplanted to a sterilized growing

medium. Those new plantlets are tender and particular care must be given to protect them against

intensive light, high temperature and dryness.

The Principles Application of Tissue Culture:

1. To establish pathogen-free plants.

2. To isolate genetically unique cell lines that can become new plant variants.

3. To enable rapid multiplication under conditions those maintain freedom from disease.

4. The production of haploid plants (the somatic cells contain only a single set of chromosomes), by

growing pollen grains under aseptic conditions. Treating them with some mutagenic agents can

double chromosome number of those plants to produce homozygous diploid plants.

5. Easy handling and exporting of the new plants from one place to another.

Culturing Various Tissues and Organs

1 -Organs culture:

a) Root culture: Dissected root pieces usually planted in medium containing yeast extraction or

vitamin B group and amino acid glycine.

b) Leaf culture: Leaf pieces could be planted on medium containing sucrose and mineral salts.

c) Shoot-tip culture: This technique is used to produce pathogen-free clones. Either a terminal or

lateral bud is grown aseptically in Agar or liquid medium containing various salts, vitamins,

nutrients and hormones. The apical bud elongates, developing several lateral shoots which

excised and subculture in a medium containing the rooting hormone IBA. After the roots

formation, the plantlets are removed from the aseptic conditions, acclimated temporarily and

transplanted outdoors.




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d) Flower culture: Excised flowers (after the completion of pollination and fertilization) are

allowed to grow aseptically in Agar medium. The planted flowers can develop into small fruits;

the fruit size can be increased by adding some hormones such as gibberellins, auxins, and

cytokinins to the growing medium.

e) Embryo and ovule culture: Embryo and ovules excised at different stages of development could

be planted on a special medium. The importance of this technique is to grow and develop such

organs that may abort at the early stages of development as in case of Thompson seedless grape.

f) Callus culture: If, under optimum culture conditions, small pieces of callus are dissected from

the base of cut stem, bark tissue or cortical cells and then cultured on an artificial medium. Some

cells of the callus will undergo various kinds of organogenesis.

g) Single cell culture: Single-cell cultures are obtained by treating callus with tissue-macerating

enzymes that dissolve the middle lamella and parts of the cell wall. The treated callus then

subjected to continuous shaking, under these conditions, small cell clumps or individual cells

appear. Single cells may be removed with a micropipette under a dissecting microscope and

transferred to a special medium (environment).

h) Protoplast fusion (See fig11.).

Fig. 11 (Protoplast fusion)

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Principles of Fruit Production (Pomology 16201) Chapter 3 ...kenanaonline.com/files/0112/112629/Lecture 4.pdf · Prof. Dr. Atef Mohamed Ibrahim Alexandria University Principles of

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