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GRAFTING:
A TECHNIQUE IN FOREST TREE BREEDING PROGRAMME
P Sharma
Divn. of Plant Breeding & Genetics
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Grafting
is a most fascinating aspect of conventional propagation
technique. The "Parts" of different plants species are
united here, by bringing the cambium of each in to contact
and cut surfaces unite and grow together. Though the technique
is widely popular in horticultural crops even it has been
recorded in many gymnosperms like Pinus, Abies etc. The
"Parts" used in the technique are "Stock" that is the
lower part of the graft and the"Scion" that is the part
of the graft and will provide new shoot system. A successful
grafting always depends on the proficiency in the grafting
skills, correct and efficient equipment and material,
stock and scion should be true to name that is both the
stock and scion should be the combination of similar genetical
affinity, intimate cambial contact between stock and scion,
the correct time of year, the correct environmental factor
such as humidity, temperature, shading and ventilation
( where appropriate), prevention of drying out of the
cut surfaces, prevention of pests and diseases etc. The
whole grafting technique includes number of methods. Among
these, the techniques basically applied in deciduous and
evergreen forest trees are following : "Open ground grafting",
is a process in which multi-budded dormant scion is grafted
on to an established open ground stock. "Bud grafting",
is normally done in summer in which a single bud with
rind (i.e.the tough outer layer of plant body) is cut
and placed within the stock. "Bench Grafting ", is carried
out at the bench inside a covered structure, that is shade
or green house during summer or winter. Here the scion
is interlocked into the stock and use a rubber grafting
strip to hold the scion and stock firmly together. Open
ground grafting is reported on Pinus(1976, Kedharnath,S
& Kapoor, M. L; 1977, Kapoor, M. L. , Vaishasya, R. K. &
Kedharnath, S; 1979, Kedharnath, S. Kapoor,M.L. & Vakshasya,
R. K.; 1981 Kapoor, M. L.).Further, a successful intergeneric
grafting in Paulownia tomentosa is done by using section
of roots as the under stock. Again,(1995,Sharma A,K., Thakur,S.,
Badiyala,S. D., and Sharma. N. K.,) reported on Terminalia
chebula through "Patch budding" an important medicinal
tree species. The technique is most appropriate to obtain
special forms of plants, to propagate plants, that are
virtually impossible to raise by any alternative vegetative
technique and to get the desired clonal material to establish
"Plus Trees". For the production of "Plus tree" species
for forestry breeding programme, considering a "Mother
tree orchard" can provide scion material and by creating
"Seed orchard" for superior seed production to maintain
good quality seed bank, it oflers a best proposal. The
main advantage of the technique is to have a strong root
system to provide anchorage to which are high yielding.
Besides this, the "Bud grafting" is most economical and
standard method in terms of space as only one bud is used
for budding compared to other grafting methods. Therefore,
it is considered that grafting technique on the whole
is the best approach in forest tree breeding programme. |
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