FINALS - Plant Propagation and Nursery Management Flashcards
Physiological condition of the mother plant can exert great influence on the rooting of cuttings. For example, cuttings taken from the plants deficient in water often show reduced rooting.
Physiological condition of the mother plant
In most plant species, the cuttings taken from juvenile (young) growth phase often root better than from adult phase. It implies that the ability of cuttings to form adventitious roots decrease with the increase in the age of the plant.
Juvenility factors
A proper choice of wood is an important factor because the wrong choice may be quite harmful as it may result in complete failure of rooting of cuttings. In general, the capacity of the cuttings to root depends upon the type of wood taken by the propagator. Usually, the cutting taken from the lateral shoots root better than the ones taken from terminal shoots.
Types of the Wood
In most species, the rooting process is inhibited if leaves and buds are removedfrom the cuttings. The promoting effect of leaves and buds in root initiation is due to the fact that these are the primary source of carbohydrate and auxin synthesis and other root promoting co-factors in the plants.
Presence of leaves and buds
The process of root initiation in cuttings taken from plants infected with viruses is inhibited or reduced as compared to those taken from virus-free stock plants.
Presence of viruses
In some plants, rooting is better when the cut is made just above or below the node, in others rooting is better if cut is made at the node and still in others, and position of the cut has no effect on root initiation process.
6.Position of the basal cut in the cutting:
In some cases, season of the year, when cuttings are made has significant influence on rooting of the cutting.
Season
Various treatments of cuttings
i) Use of growth regulators
ii) Mineral nutrients
iii) Fungicides
iv) Wounding
v) Etiolation treatment
vi) Girdling
Environmental conditions like availability of water, light, temperature and rooting media may also affect the root initiation process in cuttings. Effect of different environmental factors is
summarized as under:
i)Water condition
ii) Temperature
iii) Light
Iv) Rooting medium
The inability of two different plant parts grafted or budded together.
Graft Incompatibility
External symptoms of graft incompatibility
- Failure to form a successful graft or bud union
- Yellowing of foliage i
- Premature death of the trees
- Marked difference in growth rate of the scion and rootstock
- Over growth at, above or below the graft union
- Suckering of rootstock
- Breakdown of graft union cleanly
External symptoms of graft incompatibility
- Failure to form a successful graft or bud union
- Yellowing of foliage i
- Premature death of the trees
- Marked difference in growth rate of the scion and rootstock
- Over growth at, above or below the graft union
- Suckering of rootstock
- Breakdown of graft union cleanly
Types of Incompatibility
- Localized (non-translocated) incompatibility
- Translocated incompatibility
Graft combination in which a mutually compatible interstock overcomes the incompatibility of the scion and rootstock.
Localized (non-translocated) incompatibility
It includes certain graft/rootstock combination in which the insertion of a mutually compatible
interstock does not overcome incompatibility.
Translocated incompatibility
Some apricot cultivars grafted onto Myrobalan plum rootstock will not break at the graft union until the trees are full grown and bearing crops.Graft incompatibility can take as long as 20 years to occur. Other examples are conifers, oaks and
cherry on pazza (Prunus cerasoides) rootstocks.
Delayed Incompatibility
These graft union failures resemble incompatibility symptoms, but are due to pathogens like virus or
phytoplasma. Tristeza is an important example of virus induced incompatibility in citrus. Failure of sweet orange (Citrus sinensis) budded onto sour orange (Citrus aurantium) rootstock is due to toxic substance from sweet orange, but lethal to the sour orange rootstock.
Pathogen induced incompatibility
Causes and mechanism of incompatibility
- Physiological and biochemical mechanism
- Modification of cells and tissue
- Cellular recognition
In case of incompatible combination of certain pear cultivars on quince rootstock, the incompatibility
is caused by a cyanogenic glucoside, prunasin, normally found in quince, but not in pear tissues.
Physiological and biochemical mechanism
The lignification process of cell in walls is important in the formation of strong union in pearquince grafts.
Modification of cells and tissue
“Cellular recognition is defined as the union of specific cellular groups on the surface of
the interacting cells that results in specific defined response e.g. pollen-stigma compatibility
recognition responses with glycoprotein surface receptors in flowering plants.”
Cellular recognition
Predicting Incompatible Combination
- Electrophoresis test
- Magnetic Resonance Imaging (MRI)
can be used to detect vascular discontinuity in bud union of
apple.
Magnetic Resonance Imaging (MRI)
This test is being used for testing cambial peroxidase banding pattern of the scion and
rootstock of chestnut, oak and maple.
Electrophoresis test
A grafted or budded plant can produce unusual growth patterns which may be different from what
would have occurred if each component part of a graft age viz.,
-Stock – Scion Relationship
Effect of stocks on scion cultivars
- Size and growth habit
- Precocity in flowering and fruiting
- Fruit set and yield
- Fruit size and quality
- Nutrient status of scion
- Winter hardiness
- Disease resistance
- Ability to resist soil adverse conditions
Effect of scion on rootstock
- Vigor of the rootstocks:
- Cold hardiness of the rootstock
- Precocity in flowering
FACTORS INFLUENCING THE HEALING OF GRAFT UNION
- Incompatibility
- Kind of plant
- Environmental factors during and following grafting
- Growth activity of the stock plants
- Propagation techniques
cause enlargement of plant cell.
Auxins
stimulate cell division, cell elongation or both.
Giberellins
stimulate cell division in plants
Cytokins
plant hormones that inhibit or retard a physiological or biochemical
process in plants.
Inhibitors
One of the oldest uses of plant growth regulators has been to initiate or accelerate the rooting of
cuttings
Rooting and Plant Propagation
a concentrated solution varying from 500 to 10,000 ppm (0.05 to 1.0 percent) of auxin in aqueous solution or 50 percent alcohol is prepared, and the basal end (0.5 to 1cm) of the cutting is dipped in it for a short time (usually 3 to 5 seconds sometimes longer).
Quick dip method
. In this method, the basal end of cuttings are soaked in dilute solution (10 to 500 ppm) for up to 24hrs just before they are inserted into the rooting medium. The concentration varies from about 20 ppm for easily rooted cuttings to about 200 ppm for the difficult- to-root species.
Prolonged soaking method
In this method, the basal ends of cutting are treated with the growth regulators in a carrier-usuallya clay or a talc. The concentration of active ingredients in the inert carrier is between 500 to 1000
ppm.
Powder method
For preparing hormonal pastes, the required quantity of hormone is weighed accurately and
dissolved in a few drops of alcohol.
Lanolin paste method
