Use of Rootstock in Fruit Crops
A grafted or budded plant can produce usual patterns which may be different from what would have occupied if each component part of graft age viz. root stock and scion were grown separately or when it is grafted or budded in other types of rootstock. Some of these have major horticulture valve. This very inspect of rootstock in the performance of a scion cultivator or vice versa is known as stock scion relationships.
A) Effect of Stock on Scion Cultivates:
1. Size and Growth Habit:
In apple, rootstock can be classified as dwarf, semi dwarf vigorous and very vigorous rootstock based on their effect on a scion cultivator. If a scion is drafted on dwarf rootstock the graft combination will be dwarf while he same cultivar grafted on very rootstock would grow very vigorously. In citrus, trifoliate oranges. On the other hans, in mango all plants of a given variety are known to have the same characteristic canopy shape of the variety despite the rootstocks being of seedling origin. But recently, rootstock of kakarady, olour have been found to impart dwarfness in the scion cultivators. Guava cultivars grafted on psidium puminum are found to be dwarf in statue.
2. Precocity in Flowering and Fructing:
The time taken from plating to fruiting precocity) is influenced by rootstocks. Generally fructing is influenced by rootstocks. Generally fruiting precocity is is associated with dwarfing rootstocks and slowness to start fruiting with vigorous rootstocks. Mandarins, when grafted on Jamberi rootstock are precious than those grafted on sweet orange or sour orange or acid lime rootstock.
3. Fruit Set and Yield:
The rootstock directly influence on the production of flowers and setting fruit in oriental persimmon ( diospyrous kakij cv. Hichiya ). When it is grafted on D. Lotus I products more flowers but few only mature but when D. Kakij is used as the rootstock, the set is more.
The influenced of rootstock on the yield performance or cultivar has been well documented in many fruit crops. Acid limes budded on rough lemon register nearly 70 percent increased yield than those budded on troyer citrange, Rampur lime or its own rootstock. Sweet orange var. satngdi budded on kichili rootstock rootstock gave higher yield than on Jamberi or on its own seeding (South India).
4. Fruit Size and Quality:
Sathgudi sweet oranges grafted on gjanimma rootstock produced large but poor quality fruit, while on its own roots they produced fruit with high juice content and quality. The physiological disorder ‘granulation’ in sweet orange is very low of grafted on Cleopatra mandarin seedling, on their hand rough lemon seedling, stocks induced maximum granulation. The physiological disorder ‘black end ‘in Barlett Pear did not appear if Pyrus Communis was used as the rootstock Ehen P. pyrisfolia was used as the rootstock. This disorder appeared, affecting fruit quality.
5. Nutrient Status of Scion:
Rootstocks do influence the nutrient status of scion also. Sathgudi sweet oranges trees have a better nutrient in the leaves when on it’s budded on C. volkarminriana rootstock than on its own rootstock or Cleopatra mandarin stocks.
6. Winter Hardiness:
Young grape fruit tree on Rangpur lime withstand winter injury better than on rough lemon or sour on orange. Sweet orange and Mandarins on trifoliate were more cold hardy.
7. Diseases Resistance:
In citrus considerable variability exists among the rootstock in their response to diseases and nematodes. For instance rough lemon rootstock is tolerate to tristeasa, xyloprosis and exocorita is tolerant to gummosis but susceptible to exocorita virus disease. Similarly guava varieties grafted on chinse Guava, resist wilt diseases and nematodes.
8. Ability to Resist Soil Adverse Conditions:
Among the citrus rootstocks trifoliate orange exhibits poor ability to resist excess soil moisture or excess boron in the soil. Myroblam plum rootstock generally viz, peach, appreciator almond.
B) Effect of Scion on Root Stock:
1. Effect on Root System of Stock:
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 growth and the dry ultimate size of the tree is more determinate by the scion rather the rootstock.
2. Cold Hardiness of the Rootstock:
Cold hardiness of citrus roots is affected by the scion cultivar. Sour orange seedling budded to ‘Eureka ‘lemon suffered much more from winter injury than the unbudded seedlings.
3. Age of Root Stock Seedling:
Young mango rootstock seedling (6 month 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 oats are difficult to graft but apple and pears are very easy in predicting a successful graft union.
3. Environmental Factor During and Following Grafting:
There are certain environment al requirements which must be met for callus tissue 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 tissue. In most of the temperature fruit crops callus production is retarded after 100 0 F.
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 content 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 grafting depend upon the bark ‘spipping’ which means the cambila cells activity dividing and producing young thin walled cells on the side of the cambium. These newly formed cells separating readily from one another as the book slips.
5. Propagation Techniques:
Sometimes the technique used in grafting is so poor that only a small portion of the causal regions of the stock and scion are brought together. This measurement in its failure of the graft union.