Population Development for the Selection of High-Yielding Soybean Cultivars with Resistance to Iron-Deficiency Chlorosis1
- R. W. Hintz,
- W. R. Fehr and
- S. R. Cianzio2
Soybean [Glycine max (L.) Merr.] genotypes with an exceptionally high level of resistance to iron-deficiency chlorosis on calcareous soil have been developed by recurrent selection. The objective of this study was to compare alternative strategies for the use of the highly resistant genotypes as parents in developing populations from which high-yielding cultivars with chlorosis resistance could be selected. Single-cross populations were developed by mating two highly resistant genotypes with three high-yielding, chlorosis-susceptible lines. The F2-derived lines from each single cross were evaluated for chlorosis resistance on calcareous soil in the field, and the superior ones from each population were backcrossed to the high-yielding parent. The F4-derived lines from the single-cross populations and BC1F3-derived lines from the backcross populations were evaluated for seed yield on noncalcareous soils and for chlorosis resistance on calcareous soil. The backcross populations had a higher mean yield and a lower level of chlorosis resistance than did the single-cross populations. Seven percent of the lines in the single-cross populations and 1% of the lines in the backcross populations were equal to the highly resistant parents for chlorosis resistance. An average of 36% of the lines in the single-cross populations and 43% of the lines in the backcross populations had a seed yield not significantly different from the recurrent parent and chlorosis resistance not significantly less than a check cultivar with acceptable resistance. Phenotypic correlations between the yield of lines on noncalcareous soil and their chlorosis resistance on calcareous soil were not significant in half of the populations and were negatively associated (p<0.01) in the other populations. The negative correlations indicated either that there was no physiological association between the traits or that the association was favorable for the selection of high-yielding lines with chlorosis resistance.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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