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Results and discussion
D-genome substitution lines x Secale cereale crosses
A wide range in crossability percentage was obtained in different
substitution lines and the control gLangdonh as seen in Table
1. Analysis of t-test of all the crosses, except 3D(3A) x rye and
4D(4A) x rye, revealed a highly significant (p<O.Ol) each the
D-genome substitution lines in crossability with rye according to
control.
Mean crossability percentage ranged from 12.7 for the 2D(2B) to 52.9
for the 7D (7A). When the crossability percentages are compared, it
was shown that the crossability percentages in five of the disomic
substitution, viz, lD(lA), 6D(6A), 7D(7A), 5D(5B) and 6D(6B) were
significantly higher than the control, while other of the disomic
substitution lines, except 3D(3A) and 4D(4A) were significantly lower
than the control. Especially, 7D(7A) line showed the highest
crossability with rye, while 2D(2B) and 5D(5A) lines showed the
lowest crossability with rye. Crossability percentages in three of
the disomic substitution lines of A genome chromosomes with rye were
significantly higher than the control, while those in only two of the
disomic substitution lines of B genome chromosome with rye were
significantly higher than the control. These results showed that B
genome chromosome substitutions had a more detrimental effect on
kernel set than A genome chromosome substitutions. Similar results
were obtained by Pienaar and Marais (1986).
As can be seen in Table 1, the 5D(5B) substitution line showed a
higher crossability with rye than the 5D(5A) substitution line. It
was clearly shown that, as previously reported by Riley and Chapman
(1967), gene Krl located on the 5B chromosome was more
detrimental to kernel seed set than gene Kr2 located on the
5A. Zheng et al. (1992) reported that the gene Kr4 is located
on chromosome 1A of wheat. As can be seen in Table 1, the lD(lA)
substitution line showed significantly high crossability with rye,
suggesting that 1A chromosome may be partly responsible for the
crossability of wheat with rye.
At the same time, Miller et al. (1983) reported that the homoeologous
group 3 chromosomes carry genes affecting chromosome pairing and
crossability. As can be seen in Table 1,
the 3D(3A) substitution line showed normal crossability according to
control (Langdon), while 3D(3B) substitution line showed
significantly lower than control. In this study, it was also observed
that the crossability percentage drastically decreased when 3B was
absent. This results indicate that the 3A chromosome has a more
detrimental effect on kernel seed set than the 3B chromosome. Also,
this data supports Romero and Cuadrado (1992) who reported that
crossability level of CS-mono 3B line was lower than CS-mono 3A line.
This results showed that 3A chromosome has more important effect on
crossability with rye than 3B chromosome.
On the other hand, Tanner and Falk (1981) reported that rye has a
single dominant gene for crossability with wheat. The cause of
variation in crossability percentage in these crosses, except 3D(3A)
x rye, 3D(3B) x rye, 5D(5A) x rye, 5D(5B) x rye and lD(lA) x rye,
could not be explained. Perhaps, the heterozygosity for a factor
affecting crossability percentage was present in the Secale
cereale parent.
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