ARTIFICIAL
REGENERATION Compiled by-Nripesh Awasthi
“Artificial
regeneration is defined as renewal of forest crops by sowing, planting or other
artificial method. It also refers to the crops so obtained.” Normally such
crops is called plantation.
OBJECT OF A.R.
1. Reforestation- restocking of felled or other cleared woodland by artificial means. The
place has vegetation before.
Objective:
·
To
supplement natural regeneration.
·
To
give up natural regeneration in favor of artificial regeneration.
·
To
restock forest destroyed by fire or other biotic factors.
·
To
change the composition of crops.
·
To
introduce exotics.
2. Afforestation- establishment of forest by artificial means from which forest vegetation
has long been absent or always been absent.
Objectives:
·
To
increase the production of timber.
·
To
increase the production of fuel and small timber.
·
Improvement
of agro ecosystem
·
Moderation
of climate.
·
Soil
conservation
·
Protection
of catchment of rivers.
·
Increasing
natural beauty of landscape.
Artificial regeneration by:
1. Seed
2. Vegetation method
1. A.R. from seed
a) Direct sowing
Ø Applied to areas, where soil
operation is difficulties or soil tillage is difficult due to risk of landslide
or cliff-terrain.
Ø Fine seed mixed with sand and
directly sowing can be done.
Eg:
utis, khair, etc.
b) Seedling plantation
Ø Seedling are raised in nursery and
transplanted into field during monsoon using polypot size 3*7.
Ø Seedling such as bare rooted plant,
large ball rooted seedling or stump (root-shoot cutting) are used in seedling
plantation.
Ø Survival rate of bare rooted plant is
low but easy and cheap for handling and transportation to the site, eg: utis, Cryptomeria
japonica.
Ø Laborious and costly in handling and
transporting in case of large ball rooted plant.
Ø Stumps are being used in Nepal mainly
for Dalbergia sissoo, Tectona grandis, Cassia siama, etc.
2. A.R. from vegetative parts:
Regeneration from somatic parts of
plant such as root, stem, leaves and bud accomplished by asexual reproduction
is called regeneration from vegetative parts. Crops remain true to their parent
and mature early. ie; Budding, cutting, coppicing, cell tissue culture,
grafting, layering, root-sucker, etc.
ADVANTAGES
1. It is useful to those plant that don’t
produce viable seeds and difficult to regenerate through seed.
2. It produces large number of
population of clones in shortest time and cheaper.
3. It preserves purity, resistance and
good quality of races indefinitely.
4. It maintains genetic uniformity to
parental plants.
A)
BUDDING
In it,
a bud with some portion of bark of a genetically superior plant is grafted on a
inferior plant, so that it may produce new shoot when shoot of stock is cut
off.
Eg:
apple, peach, etc.
B)
CUTTING
It is
cut piece of root, stem and leaves which is planted in nurseries. In it, root
promotive hormones are added such as IBA, NAA, etc. It is used when seeds are
not available of a species or difficult to raise from to seed. It reduces time
for growing in nurseries and maintains genetic ideal plants.
Stem
cutting- rose, sugarcane, bougainvillea, etc.
Root
cutting- apple, lemon, etc
Leaf
cutting- snake plant (sansevieria)
C)
COPPICING
It is
defined as shoot arise from the adventitious buds at the base of woody plants
that has been cut near the ground or burnt back. It may be seedling coppice and
stool coppice. It is good for highly sprouting deciduous broad leaved species
aiming for production of small sized timber and fuelwood. It depends on
following factors.
1. Species
Ø Strongly coppice: sal, khair, salix,
Syzigium, Morus alba, Tectona grandis, Dalbergia spp, etc.
Ø Coppice fairly: okhar, asna,
terminalia spp, etc.
Ø Coppice badly: Adina cardifolia,
Bombax ceiba, Casuariana equisettifolia, etc.
Ø Donot coppice: coniferous plants.
2. Age of trees: younger trees coppices
rapidly.
3. Season of coppicing: little before
the growth starts in spring.
4. Height of stumps: 15-25 cm being very
suitable.
D)
CELL TISSUE CULTURE
It is
also called micro propagation. It includes propagation of plants by culturing
the cells, tissues, and organs especially on artificial medium in suitable
containers under controlled environment condition which is called tissue
culture. The part which is cultured is called explants. This capacity to
generate whole plant from any cell or explants is called cellular totipotency.
E)
GRAFTING
It is
technique of connecting two parts; usually root system and shoot system of two
different plants in a such a way that they unite and later develop into
composite plants. In it, scion and stock are united by callus and cambium-
cambium union is necessary. Common technique are crown grafting, side grafting,
approach grafting, tongue grafting, wedge grafting, etc. Generally cleft
grafting is useful in forestry.
Eg:
pine, mango, rubber plant, citrus plant, plum, peach,etc
F)
LAYERING
It is
a type of rooting cutting in which adventitious roots are induced to develop on
a stem while it is still attached to the plant. It is carried out on one year
old basal shoot branches commonly during early spring or early rainy season.
Ø Air layering/gootee: It is practiced in tropical and subtropical
trees and shrubs. In it, 3-5 cm long ring of bark is removed from basal region
of healthy and woody branch and covered by grafting clay (1 part cowdung or 1
part cut hay or mosses), rooting hormone wrapped in polythene.eg; litchi,
pomegranate,etc.
Ø Mound layering/ soil layering: In it,
branch is pruned, lowered part of it covered with soil. Then a number of shoot
is developed and rooted shoot are separated for planting.eg; apple, pear, etc.
G)
ROOT SUCKER
It is
process in which root is partially or wholly cut to produce shoot is called
root sucker propagation. Eg; sissoo, simal, etc.
Reference:
-Khanna L.S (2011). Principles and Practice of Silviculture.
-Various books and magazines.
