Grafting
Grafting
A grafted plant is composed of
two parts. The basal part which provides the roots system for anchorage and
absorption of moisture and nutrients is called the rootstock. The scion provides top and fruits bearing
surface and synthesize food which is transported to other parts of the plant.
Scion and root stock should be compatible and closely related belonging to the
same genus.
Grafting is a process by which a
piece of scion is attached to a rootstock in such a way that the cambium of
both scion and rootstock come in firm contact so that the new secondary tissue
resulting from cambial cell division in the scion and rootstock is closely
knitted. The stock usually influences the size and vigour of the tree and the
scion the yield and quality of fruit it will bear. Grafting allows utilization
of varying climatic, soil and biotic conditions with advantage. When a single
bud is used as scion and inserted into the rootstock the method is called
budding, whereas when a piece of stem or
branch carrying one or more than one bud is used the process known as grafting.
Several important methods of grafting used to vegetative propagation of fruits
and ornamental trees.
The first step in the budding and
grafting operation is to raise seedlings of compatible rootstock species or to
produce clonal rootstocks to avoid variation otherwise encountered in seedling
populations. If seedlings are used only strong and healthy ones should be
selected to be used at rootstock.
The selection and care of scion
wood is of the most importance. It must be collected from selected progeny trees
which are true-to-type and have desirable fruits and yield characteristics. Twigs
that have shown growth during the previous season usually furnish the best
scion wood. The buds should be well developed, plump, mature, and in dormant
condition. If the bud wood is not utilized immediately, it can be stored for a
limited time. The sticks of bud wood are tied in small lots and properly labelled
for identification. Both the ends are sealed in melted wax to prevent excessive
evaporation. The bundles are then put in sphagnum moss, wrapped in polythene
bags, packed in a suitable box, and stored in a cool place.
Only the most compatible scion
and rootstock combinations should be used in grafting and budding. Incompatible
combinations result in poor bud take, weak graft or bud union, overgrowth of
stock as compared to scion or vice versa, low disease resistant, excessive leaf
drop, early decline, low yields of poor quality fruit, and short life span.