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14.

In modern times grafting has superseded the use of seedling
trees in those regions where there is extensive commercial
cultivation on an orchard basis. Though seedlings ultimately
attain a larger size than grafted trees, the latter assure
reproduction of the desired variety, begin production at an
earlier age, and can be placed on rootstocks which give resistance
to unfavorable soil conditions and certain diseases.
Nucellar seedlings are of great value in connection with
nursery work, assuring a high degree of uniformity among
seedling rootstocks; they have also been useful in connection
with the development of virus-free strains of fruits, since viruses
are not usually transmitted through seeds.

Rootstocks

Choice of the rootstock for budding (or other type of
grafting) is one of the most important decisions that the orange
grower is called on to make. Stocks differ in their adaptation
to soil conditions--drainage, salinity, texture, pH value--and
to various pests--fungi, insects, and viruses. No one stock is
best under all conditions, and under the same conditions a stock
which is best for one kind of citrus fruit may not be best for
another. The stocks most commonly used for oranges: Rough lemon,
sour orange, Cleopatra mandarin, sweet orange, Rangpur lime,
trifoliolate-orange, and citranges. All of these produce high
percentages of seedlings which are quite uniform in character.

Rough lemon (C. jambhiri or C. limon) is best adapted to
deep, well-drained, sandy soils on which it produces larger trees
in a given time than other stocks. However, fruit is inferior
in quality to that of the other common stocks. This is not