Volume 30 Number 1 Article 38 Pages: 34-34
Year 1976 Month 1
Title: Interspecific Hybridization in Citrus Rootstocks
Author: D.J. Hutchison
Citation
Abstract:
The citrus rootstock greatly influences
yield, fruit quality, tree size,
disease resistance, cold hardiness,
drought tolerance, and salt tolerance.
In practice, virtually all commercial
citrus trees are grafted to a rootstock.
In many citrus rootstocks, apomictic
(nucellar embryony) seed production
produces a uniform seedling population
to graft with the scion and is of
great practical value.
The main objectives
of our citrus rootstock breeding
program are to produce hybrids
that are: disease resistant, reproduce
by nucellar embryony, and have horticultural
characteristics necessary to
produce high quality citrus fruit economically.
The Florida citrus industry has used
sour orange (Citrus aurantium L.) and
rough lemon (C. limn ( L. ) Burm. f. )
as their basic rootstocks.
Because of
their genetic vulnerability, suitable
substitutes are needed.
Attempts to
E roduce interspecific citrus rootstock
ybrids have been largely unsuccessful.
Hybrids being used by the citrus
industry have been produced by crossing
C. sinensis (L.) Osbeck and C.
paradisi Macf. with Poncirus trifoliata x.
( L. ) Raf.
Some of these intergeneric
hybrids have shown disease resistance,
apomictic reproduction, and favorable
horticultural characteristics necessary
in citrus rootstocks.
The use of intergeneric
hybridization in citrus rootstock
is probably unique, as they
are easily intercrossed, produce fertile
progeny, and have compatible budunion
relationships.
At resent, five
genera are being used in this program,
Citrus, Eremocitrus, Fortunella, Microcitrus,
and Poncirus. Two other
genera (Citropsis and Severinia) have
desirable traits but so far have not
been found to be interfertile with
Citrus.
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