| The performance of randomly selected progeny from the segregating populations
was similar to that of the parents (Table 3).
The reciprocal control crosses, Chris/Selkirk and Selkirk/Chris, gave similar
responses. The performance of progeny in the Ae. bicornis cytoplasm
was significantly lower than the controls for plant height, grain yield,
and test weight, (family 14 vs family 11, and family 19 vs family 16). The
performance of progeny in the Ae. squarrosa cytoplasm was also lower
for grain yield and test weight, but was higher for plant height, although
none of these differences were significant from the respective control progeny
(family 15 vs family 11, and family 20 vs 16). The progeny of crosses involving
euplasmic parents of one cultivar with alloplasmic parents in either Ae.
bicornis or Ae. squarrosa cytoplasm of the other cultivar produced
results similar to euplasmic parents formed by crossing euplasmic control
with alloplasmic parents of the same cultivar. The male parent in Ae.
bicrnis cytoplasm, increased plant height and test weight beyond the
respective control progeny with grain yield being equal, (family 12 vs family
11 , and family 17 vs family 16). The male parent in Ae. squarrosa
cytoplasm gave higher grain yield and test weight with shorter plants (family
13 vs family 11, and family 18 vs family 16). The range in individual progeny performance was essentially the same among all crosses for days to head and test weight. However, genes for plant height were cytoplasm sensitive. The Ae. bicornis cytoplasm gave the shortest individual line while the Ae. squarrosa cytoplasm gave the tallest individual line. The response of grain yield to the two alien cytoplasmic backgrounds was similar. The highest yielding individual line in each cytoplasm did not exceed the highest yielding individual line in the respective controls. However, the grain yield of progeny from crosses of euplasmic parents of one cultivar as female with alloplasmic parents of the other cultivar as male responded in a positive manner. In this type of cross, grain yield was enhanced over the reciprocal cross and, in fact, the highest yielding individual lines were in crosses in which the alloplasmic Ae. squarrosa line was used as the male. These individual lines showed 8 to 10% heterosis over the highest yielding individual in the respective control crosses. The alloplasmic parents may have differential transmission of male gametes with a more desirable genetic constitution when returned to the normal cytoplasm. This possibility is consistent with certain alloplasmic pentaploid wheat hybrids having a strong influence on the preferential transmission of male gametes with specific chromosomal constitution which was not observed in euplasmic control pentaploid wheat hybrids (3). Conclusion The relationship between the performance of alloplasmic lines and segregating populations having the same cytoplasm appears to be stable and predictive. The mean yield of alloplasmic lines in the Ae. bicornis cytoplasm was 86 and 84% of the euplasmic Chris and Selkirk controls, respectively. The mean yield of crossed progeny in the Ae. bicornis cytoplasm was 88 and 82% of the respective controls while the yield of the best individual line in the crossed progeny in Ae. bicornis cytoplasm was 87 and 88% of the best individual in the corresponding euplasmic control cross. Similar responses were noted with the Ae. squarrosa cytoplasm. Thus, knowing the performance of an alloplasmic line in comparison to the respective euplasmic control should give a reliable estimate of the performance of the alien cytoplasm in crosses. However, when the alloplasmic line is used as a male parent in crosses, performance of the progeny may be improved beyond the performance of the euplasmic control. Literature Cited BUSCH, R.H., and S.S. MAAN. 1974. Possible use of cytoplasm variability in wheat improvement. Wheat Newsl. 29: 163-166. BUSCH, R.H., and S.S. MAAN. 1978. Effects of alien cytoplasms on agronomic and bread-making traits of two spring wheat cutlivars. Crop Sci. 18 : 864-866. TSUJI, S. 1979. Cytoplasmic relationships among the D-genome Aegilops species. Ph. D. Thesis. North Dakota State University, Fargo, ND. |
| <-- Back |