CH Plant Propagation 1 — Questions and Answers
Question 1: Which type of cutting is taken from the actively growing, soft tip of a stem and roots most quickly but wilts most easily?
- Hardwood cutting
- Softwood cutting (Correct answer)
- Semi-hardwood cutting
- Leaf-bud cutting
Correct answer: Softwood cutting
Softwood cuttings taken from new, non-lignified stem tips root rapidly because cells are actively dividing, but require high humidity to prevent wilting before roots form.
Question 2: Stratification of seeds is a pre-germination treatment that involves:
- Soaking seeds in a gibberellin solution
- Exposing seeds to a period of cold and moist conditions to break dormancy (Correct answer)
- Scarifying the seed coat with acid
- Drying seeds at high temperature
Correct answer: Exposing seeds to a period of cold and moist conditions to break dormancy
Cold-moist stratification mimics winter conditions, breaking physiological dormancy in many temperate woody plants so they germinate in spring.
Question 3: Scarification of seeds is performed to:
- Provide cold treatment for dormancy breaking
- Break or weaken the hard seed coat to allow water imbibition (Correct answer)
- Apply fungicide treatments
- Improve seed storage life
Correct answer: Break or weaken the hard seed coat to allow water imbibition
Scarification physically or chemically abrades the impermeable seed coat of hard-seeded species, allowing water and oxygen to enter and initiation of germination.
Question 4: Grafting is a vegetative propagation technique primarily used to:
- Produce plants from seed quickly
- Combine desirable scion traits with rootstock vigor, disease resistance, or adaptability (Correct answer)
- Induce polyploidy in ornamentals
- Eliminate the need for pruning
Correct answer: Combine desirable scion traits with rootstock vigor, disease resistance, or adaptability
Grafting unites a scion (desired cultivar) with a rootstock chosen for vigor, soil adaptation, pest resistance, or size-controlling properties, combining the best traits of each.
Question 5: Auxin (IBA or NAA) is applied to stem cuttings to:
- Prevent fungal infection
- Promote adventitious root formation (Correct answer)
- Speed shoot growth after rooting
- Harden off the cutting before transplanting
Correct answer: Promote adventitious root formation
Indole-3-butyric acid (IBA) and naphthaleneacetic acid (NAA) are synthetic auxins that stimulate the formation of adventitious roots at the base of cuttings.
Question 6: Tissue culture (micropropagation) is preferred for propagating some plant species because it:
- Requires no sterile conditions
- Produces large numbers of genetically uniform, disease-free plants rapidly (Correct answer)
- Only works with seed propagation
- Is less expensive than cuttings
Correct answer: Produces large numbers of genetically uniform, disease-free plants rapidly
Tissue culture propagates thousands of identical, pathogen-free plantlets from tiny explants in sterile conditions, enabling rapid large-scale production of superior clones.
CH Plant Propagation 1
Which type of cutting is taken from the actively growing, soft tip of a stem and roots most quickly but wilts most easily?