Volume 30 Number 1 Article 22 Pages: 22-22
Year 1976 Month 1
Title: Sterility in Rubus
Author: F.J. Lawrence
Citation
Abstract:
Maximum druplet set in raspberry
and blackberry clones is important to
obtain the highest potential yield of
fruit that will withstand harvest and
handling.
The cost of growing seedlings
for evaluation also makes the
identification of breeding lines that
transmit high druplet counts very important,
as this will reduce the numbers
of plants that will be discarded.
Sterility may be complete or partial
and originate from several causes, including
viruses and mutations.
Aneuploidy in breeding within the
higher ploidy levels (6X-9X) of blackberries
has not reduced druplet set
as much as expected, but combinations
using thornless 4X types with
6X-9X types has produced considerable
sterility in seedlings, although
occasional types with good set are recovered.
The relationship between
thornlessness and sterility are not
clear.
The pollen source in blackberry
combinations appears to be important
in the druplet set of the progeny.
OR-US
clones selected from the same cross
and used as pollen sources with the
same maternal parents had progeny
with differing druplet sets.
Partial and complete sterility is still
a problem in progeny of red raspberry
crosses.
The cultivars 'Matsqui', 'Sumner',
'Sentinal', 'Sentry', and the clone
'OR-US 3919', when intercrossed, produced
completely sterile progeny in
ranges of 12 to 26%. Crumbly fruited
seedlings were also produced in these
crosses, along with normal types.
Cul- ,
tivars 'Canby', 'Meeker', 'Puyallup',
'Southland' and clones 'OR-US 1094'.
'1314, '1394, '1406', '1412', '1416' and
'1444' produce crumbly seedlings
when intercrossed and in combination
with those clones that produce completely
sterile seedlings.
Much of this
sterility in the seedlings is assumed to
be from a reduced number of functional
embryo sacs because of ample
pollen available from clones, cultivars
and other seedlings nearby.
A common
parent in the OR-US clones is a
derivative of Rubus strigosus from Mt.
Mitchell, N.C. used for plant survival
on heavy soils.
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