Grafting in Plants

30 Grade 9 Agriculture questions on Grafting in Plants, with worked marking schemes. 30 questions are available on this topic in full.

1. Question 1

   2 marks

   Distinguish between a 'scion' and a 'rootstock' in grafting.

   (2 marks)

   Marking scheme

   Scion: the upper part/detached shoot or bud that is joined on and develops into the shoot system, carrying the desired variety (1 mk). Rootstock: the lower rooted part of the plant that provides the root system onto which the scion is joined (1 mk). Total 2 mks.

2. Question 2

   1 mark

   Which of the following pairs of plants can be successfully grafted together?

   A. Two closely related plants, e.g. two citrus varieties

   B. A bean scion on a cactus

   C. A rose scion on a grass plant

   D. A mango scion on a maize plant

   (1 mark)

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3. Question 3

   6 marks

   A fruit farmer wants to propagate improved mango varieties on his farm and decides to use grafting rather than seeds.

   (a) Give two advantages of propagating mangoes by grafting instead of by seed. (2 marks)

   (b) Distinguish between the 'scion' and the 'rootstock' as used in grafting. (2 marks)

   (c) State two conditions necessary for successful grafting. (2 marks)

   (6 marks)

   Marking scheme

   (a) Advantages of grafting over seed (any 2 = 2 marks): - Grafted plants are true to type / retain the desired qualities of the parent (mother) plant, unlike seedlings which may vary. - Grafted plants mature and bear fruit earlier than seedlings. (Also acceptable: combines good qualities of two plants e.g. disease-resistant rootstock; allows propagation of varieties that do not breed true from seed.) (b) Scion vs rootstock (2 marks): - The scion is the upper part (a shoot, stem or bud) of the desired variety that is joined onto another plant and develops into the shoot system bearing the fruits. - The rootstock (stock) is the lower, rooted part of the plant onto which the scion is grafted and which provides the root system. (c) Conditions for successful grafting (any 2 = 2 marks): - The cambium layers of the scion and the rootstock must be in close contact (aligned). - The scion and rootstock should be compatible (closely related / same or related species). (Also acceptable: the union should be tied firmly and covered/sealed to exclude air and prevent drying and entry of disease; grafting should be done at the right time when plants are actively growing, using healthy, disease-free materials of similar thickness.)

4. Question 4

   1 mark

   After joining the scion and rootstock, the union is tied and covered with grafting tape or wax mainly to:

   A. Speed up flowering the next day

   B. Add nutrients to the graft

   C. Give the plant colour

   D. Prevent drying out and entry of disease-causing organisms

   (1 mark)

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5. Question 5

   6 marks

   Describe the procedure of whip (tongue) grafting a fruit tree scion onto a rootstock.

   (6 marks)

   Marking scheme

   Award up to 6 mks, 1 mk per correct step: select a healthy scion and rootstock of similar diameter; using a sharp sterilised knife make a long slanting cut on the rootstock; make a matching slanting cut on the scion; make small interlocking tongues on each cut surface; fit the scion onto the rootstock so their cambium layers align/match; tie the union firmly with grafting tape/string; cover/seal with grafting wax to prevent drying and disease; keep in favourable conditions and remove any rootstock sprouts. Max 6 mks.

6. Question 6

   4 marks

   State four reasons why a farmer would choose to propagate fruit trees (e.g. mango or citrus) by grafting.

   (4 marks)

   Marking scheme

   Any four, 1 mk each: grafted plants are true to type / retain desirable qualities of the parent; they mature and bear fruit earlier than seedlings; combine desirable scion (fruit) with resistant/vigorous rootstock; produce uniform plants; can incorporate disease/pest resistance from the rootstock; overcome poor rooting of some varieties. Max 4 mks.

7. Question 7

   1 mark

   Why is a disease-resistant local variety often used as the rootstock in grafting fruit trees?

   A. It prevents the scion from ever growing

   B. It makes the fruit taste like the rootstock

   C. It stops the roots from absorbing water

   D. It gives the grafted plant a strong, resistant root system suited to local soils

   (1 mark)

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8. Question 8

   1 mark

   For a graft to be successful, the cambium of the scion must be aligned with the cambium of the rootstock. This is important because the cambium is responsible for:

   A. Absorbing sunlight

   B. Storing water only

   C. Producing flowers

   D. Forming new tissues that unite the two parts

   (1 mark)

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9. Question 9

   3 marks

   Explain why it is essential for the cambium layers of the scion and rootstock to be in close contact during grafting.

   (3 marks)

   Marking scheme

   The cambium is the actively dividing (meristematic) tissue (1 mk). When the cambium layers of scion and rootstock are in close contact they divide and form new tissue (callus) that unites the two parts (1 mk), allowing continuous transport of water and food across the union so the graft takes/survives (1 mk). Total 3 mks.

10. Question 10

    1 mark

    While grafting fruit trees, a learner is told the cambium layers of the scion and rootstock must be aligned and held firmly together. Why is this alignment essential?

    A. So the colours of the two plants match

    B. So the vascular tissues unite and allow water and nutrients to flow

    C. So the graft looks neat

    D. So the scion produces flowers immediately

    (1 mark)

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11. Question 11

    1 mark

    A farmer grafts a scion from a high-yielding mango variety onto a local seedling. The main reason for grafting rather than growing the mango from seed is to:

    A. Prevent the tree from ever fruiting

    B. Retain the desirable qualities of the parent variety and fruit earlier

    C. Produce a completely new species

    D. Make the tree grow only leaves

    (1 mark)

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12. Question 12

    1 mark

    A fruit farmer in Murang'a joins a shoot from a high-yielding mango variety onto the rooted stem of a hardy local seedling. The part that provides the roots in this grafting is called the:

    A. Scion

    B. Rootstock

    C. Bud

    D. Cambium

    (1 mark)

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13. Question 13

    1 mark

    The type of grafting in which a single bud is inserted under the bark of the rootstock is specifically called:

    A. Layering

    B. Whip grafting

    C. Budding

    D. Approach grafting

    (1 mark)

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14. Question 14

    5 marks

    A fruit farmer in Murang'a wants to propagate improved mango varieties and decides to use grafting rather than growing seedlings from seed.

    (a) Define the following terms as used in grafting:

    (i) Scion. (1 mark)

    (ii) Rootstock. (1 mark)

    (b) Give three reasons why the farmer prefers grafting to raising trees from seed. (3 marks)

    (5 marks)

    Marking scheme

    (a)(i) Scion - the detached shoot/stem portion (with buds) of the desired/improved variety that is joined onto the rootstock; it forms the upper fruiting part of the new plant. (1 mark) (a)(ii) Rootstock - the lower rooted portion (the established plant with roots) onto which the scion is fixed; it provides the root system of the new plant. (1 mark) (b) Reasons for grafting (any three): Grafted trees mature and bear fruit much faster (about 2-3 years) than seedlings raised from seed (5-8 years); the new plant is true to type, retaining the desired qualities of the parent variety; allows combining good qualities of two plants e.g. a disease/drought resistant rootstock with a high-yielding scion; produces uniform plants; allows propagation of varieties that do not produce viable seed. (3 marks)

15. Question 15

    1 mark

    A scion selected for grafting should be:

    A. Dead and dry

    B. Taken from the roots only

    C. Healthy, disease-free and taken from a high-yielding parent plant

    D. Diseased so it can be cured by grafting

    (1 mark)

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16. Question 16

    1 mark

    In whip (tongue) grafting, both the scion and rootstock are cut at a slanting angle so that they:

    A. Stay permanently separate

    B. Cannot touch each other

    C. Fit closely together, increasing the contact between their cambium layers

    D. Produce more seeds

    (1 mark)

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17. Question 17

    1 mark

    One limitation of grafting as a propagation method is that it:

    A. Requires skill and is labour-intensive/slow

    B. Cannot be used on fruit trees

    C. Always destroys the rootstock

    D. Produces plants that never resemble the parent

    (1 mark)

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18. Question 18

    1 mark

    Grafting is best carried out under which conditions for the highest success rate?

    A. During the driest, hottest part of the day

    B. When the plants are dormant and dead

    C. When both scion and rootstock are actively growing and the weather is favourable (not too dry/hot)

    D. Only at midnight

    (1 mark)

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19. Question 19

    1 mark

    A fruit farmer wants to propagate a high-yielding orange variety while benefiting from a disease-resistant root system. Why is grafting a suitable technique for this goal?

    A. It combines the desirable scion (fruit) variety with the resistant rootstock in one plant

    B. It guarantees the new tree will never need watering

    C. It produces trees that are genetically different from the parent scion

    D. It removes the need for any rootstock

    (1 mark)

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20. Question 20

    1 mark

    The lower rooted part of a grafted plant, which provides the root system, is known as the:

    A. Node

    B. Scion

    C. Bud

    D. Rootstock

    (1 mark)

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21. Question 21

    1 mark

    Which tool is most suitable for making the clean, smooth cuts needed on the scion and rootstock during grafting?

    A. A blunt panga

    B. A sharp, sterilised grafting knife

    C. A pair of pliers

    D. A wooden spoon

    (1 mark)

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22. Question 22

    1 mark

    Grafting is classified as a method of:

    A. Cross-pollination

    B. Sexual reproduction by seed

    C. Tissue respiration

    D. Vegetative (asexual) propagation

    (1 mark)

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23. Question 23

    2 marks

    State two management practices carried out on a grafted plant after the graft has taken, to ensure the scion develops well.

    (2 marks)

    Marking scheme

    Any two, 1 mk each: remove/prune any shoots (suckers) arising from the rootstock below the union; loosen/remove the tying material once the union is firm to avoid strangling; provide water/shade and protect from pests; stake the plant for support. Max 2 mks.

24. Question 24

    1 mark

    After a successful graft begins to grow, any shoots that sprout from the rootstock below the union should be:

    A. Left to grow and replace the scion

    B. Removed (pruned off) so the scion gets all the growth

    C. Grafted again onto another plant

    D. Fed with extra fertiliser to grow faster

    (1 mark)

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25. Question 25

    1 mark

    A Grade 9 learner grafting a mango scion onto a rootstock is advised to match the cambium layers of the two parts. Why is aligning the cambium so important for a successful graft?

    A. The cambium gives the plant its colour

    B. The cambium is the tissue that divides and unites the scion and rootstock so they grow together

    C. The cambium stores the seeds for the new plant

    D. Cambium alignment is only needed for flowers to form

    (1 mark)

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26. Question 26

    1 mark

    In grafting, the piece of plant that is joined onto the rooted plant and forms the shoot system is called the:

    A. Stomata

    B. Rootstock

    C. Scion

    D. Cambium

    (1 mark)

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27. Question 27

    3 marks

    Kioko grafted several mango seedlings but most of the grafts died. Give three possible reasons for the failure of the grafts.

    (3 marks)

    Marking scheme

    Any three, 1 mk each: cambium layers were not properly aligned/in contact; use of a diseased or unhealthy scion/rootstock; dirty/blunt or unsterilised knife introducing disease; the union was not tied/sealed, allowing drying out or infection; grafting done in very hot/dry unfavourable weather; scion and rootstock not compatible/closely related. Max 3 mks.

28. Question 28

    1 mark

    Which of the following is an advantage of propagating fruit trees by grafting compared with using seeds?

    A. Grafted trees always grow much taller

    B. Grafting removes the need for any watering

    C. Seeds are impossible to obtain

    D. Grafted trees mature and bear fruit earlier and are true to type

    (1 mark)

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29. Question 29

    2 marks

    Define the term 'grafting' as used in plant propagation.

    (2 marks)

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30. Question 30

    1 mark

    A signal that a graft has been successful and the union has taken place is when the:

    A. Scion produces new shoots/leaves and stays green

    B. Rootstock dies completely

    C. Scion turns brown and falls off

    D. Whole plant is uprooted easily

    (1 mark)

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