Effect of Scion on Rootstock
1. In apple it has been found that if apple seedling were budded with the "Red Astrochan" apple the rootstock produced a very fibrous root system with few top roots. On the other hand, if scion cultivar is less vigorous than the rootstock cultivar the rate of growth and the dry ultimate size of the tree is more determinate by the scion rather than the rootstock.
2. Cold Hardiness of the Rootstock:
Cold hardiness of citrus roots is affected by the scion cultivar. Sour orange seedlings budded to ‘Eureka’ lemon suffered much more from winter injury than the unbudded seedlings.
3. Age of Root Stock Seedling:
Young mango rootstock seedlings (6 months to one year old) were found to put forth inflorescence when the branches from old trees are inarched which will be attributed to the influence of scion on the rootstock.
Certain rootstock 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 predicting a successful graft union.
3. Environmental Factors During and Following Grafting:
There are certain environmental requirements which must be met for callus dissues to develop and heal the graft union.
a) Temperature has a pronounced effect on the production of callus tissues. An optimum temperature as essential for the production of callus tissues. In most of the temperate fruit crops callus production is retarded after 1000F.
b) Relative humidity must be high or maintaining a film of water against the callusing surface is essential to prevent these delicate thin walled parenchymatous calls from drying.
c) Presence of high Oxygen intent near this surface is essential.
4. Growth Activity of Stock Plants:
Some propagation methods, such as ‘T’ budding and bark grafting depend upon the bark ‘spipping’ which means the cambial cells 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 book slips.
5. Propagation Techniques:
Sometimes the techniques used in grafting are so poor that only a small portion of the causal regions of the stock and scion are brought together. This measurement in is failure of the graft union.