Methods of Plant Propagation Questions and Answers

Answer: D

Rose is commercially propagated by T-budding, also called shield budding, in which a bud shield is inserted under the bark of the rootstock through a T-shaped cut. It is the standard commercial method because it is fast and gives many plants from each budwood.

Root cutting is not used for roses, and patch budding and ring budding are used for thick-barked species such as pecan, walnut and rubber, not for rose.

In T-budding a T-shaped cut is made in the bark of the rootstock, the bark is lifted, and a shield-shaped bud cut from the scion is slipped in and tied. The bark must be slipping, which is why the work is done when the plants are actively growing.

Answer: A

The key gives mature wood stem cutting. Jasmine, such as Jasminum sambac and J. grandiflorum, is commonly multiplied by stem cuttings taken from mature wood, and layering is also used. I could not find a source that compares the four options, so the choice rests on the official key.

Budding and root cutting are not the usual commercial methods for jasmine, and ‘very soft cutting’ roots poorly.

Answer: C

Acceleration of more vegetative growth is not a symptom of graft incompatibility. Incompatible grafts show poor growth, yellowing, swelling or overgrowth at the union, and breakdown of tissue at the union.

Stunted growth, excessive swelling at the union and degeneration of tissue are therefore symptoms, so option C is the one that is not.

Graft incompatibility shows as poor growth, early leaf fall, an overgrown or swollen union and a weak union that breaks. More vegetative growth after grafting indicates compatibility, so it is not a symptom of incompatibility.

Answer: B

Meristem culture is the growing of shoot tips in vitro to get plantlets. It is used for virus-free planting material.

Anther culture grows anthers, organ culture grows organs, and callus culture grows undifferentiated tissue, so they are not the culture of shoot tips.

Meristem culture uses the tiny dome of tissue at the shoot tip, which is usually free of virus, so the plantlets that grow from it are healthy planting material. It is widely used for banana, potato and orchids.

Answer: A

Mazzard (Prunus avium) is a suitable rootstock for cherry, being a wild sweet cherry that is vigorous and compatible.

Ruggeri and Oblong are not cherry rootstocks, and Manilkara hexandra (khirni) is a rootstock used for sapota.

Mazzard is a seedling of the wild sweet cherry used as a vigorous rootstock for sweet cherry. The other three options are not cherry rootstocks.

Answer: A

Micro-propagation is the in vitro method commonly used to propagate fruit crops, since it gives many plants from small plant parts in culture. Banana is a well-known example.

Marker assisted selection is a breeding tool, haploid production is for breeding, and gene editing is for modifying genes, none of which multiplies plants.

Micro-propagation produces many plants from a small piece of tissue in culture, and it is used for banana, strawberry, grape and other fruit crops. The other options are breeding tools.

Answer: C

Dogridge is a salt tolerant rootstock for Grape.

Dogridge is a vigorous American grapevine (Vitis champinii) widely used as a rootstock in India, especially in Maharashtra and Karnataka. Grafting table grapes such as Thompson Seedless onto it gives tolerance to salinity and drought and greater vigour and yield.

Citrus, mango and plum have their own rootstocks, such as Rangpur lime and Rough lemon for citrus and polyembryonic types such as Kurukkan for mango, but Dogridge is a grape rootstock.

Answer: A

Rose is commercially propagated by 'T' budding.

In T-budding (shield budding), a T-shaped cut is made in the bark of the rootstock and a single bud with a shield of bark from the desired variety is slipped under the flaps and tied. It is quick, cheap and gives a high success rate on rootstocks such as Rosa indica var. odorata (Edward rose), so it is the standard commercial method for roses.

Patch, ring and Forkert budding are slower, specialised methods meant for thick-barked trees; Forkert budding, for example, is the standard method for rubber. They are not used for commercial rose propagation.

Answer: C

The answer is Psidium friedrichsthalianum (Costa Rican or Chinese guava).

This species is used as a guava rootstock because it is graft-compatible, dwarfing and resistant to guava wilt, which Edward and Shankar (1964) reported; it is also reported resistant to nematodes. Grafting a commercial guava on it gives a smaller tree that escapes the wilt that kills ordinary seedling rootstocks.

The other species named are not the ones given for combining a dwarfing habit with wilt resistance in rootstock lists, so the choice rests on P. friedrichsthalianum.

Answer: C

The structure used is the Mist chamber.

A mist chamber sprays a fine film of water over leafy cuttings at intervals. The film keeps the leaves cool and turgid and cuts transpiration, so the cutting keeps photosynthesising and survives for the weeks it takes to form roots. This makes it the standard method for difficult-to-root species such as mango, litchi and guava, often combined with auxin treatment.

A lath house only shades plants, a hot bed provides bottom heat for raising seedlings, and a cold frame protects plants from cold without heat. None of them controls the humidity around a leafy cutting as a mist chamber does.