Plant Propogation and Nursery Management

Factors Influencing the healing of graft union

1. Incompatibility: Certain rootstocks and scions are incompatible, therefore the graft union between these two will not normally take place.
2. Kind of plant: Some species like oaks are difficult to graft, but apple and pears are very easy in producing a successful graft union.
3. Environmental factors during and following grafting: There are certain environmental requirements which must be met for callus tissues to develop and heal the graft union.

a) Temperature has a pronounced effect on the production of callus tissues. An optimum temperature is essential for production of callus, In most of the temperate fruit crops callus production is retarded after 42.5º C.
b) Relative humidity must be high is maintaining a film of water against the callusing surface is essential to prevent these delicate thin walled parenchymatous cells from drying.
c) Presence of high oxygen content near this surface is essential.

 4. Growth activity of the stock plants: Some propagation methods, such as ‘T’ budding and bark grafting depend upon the bark slipping which means the cambial cells are actively dividing and producing young thin walled cells on the side of the cambium. These newly formed cells separate readily from one another as the bark slips.
5. Propagation techniques: Sometimes the techniques used in grafting are so poor that only a small portion of the cambial regions of the stock and scion are brought together. This may result in failure of the graft union.