Effectiveness of Nutrient-Solution Evaluation for Recurrent Selection for Fe Effeciency of Soybean
Recurrent selection for Fe efficiency resulted in a soybean [Glycine max (L.) Merr.] population with a high percentage of segregates that showed little or no yellowing when grown on calcareous soil in the field. Further improvement for Fe efficiency in the AP9 population required the development of an alternative method of enhancingenetic variability. The objective of this research was to determine the effectiveness of nutrient-solution evaluation in a recurrent selection program for the improvement of Fe efficiency. One hundred random S0-derived lines of the Cycle 6 (C6) population and the parents of the Cycle 0 (CO) through Cycle 7 (C7) populations were evaluated for Fe efficiency in nutrient solution in the greenhouse and on calcareous soil in the field during 3 yr. Entries were rated for chlorosis on a scale of 1 = no yellowing to 5 = severe yellowing. In the C6 population, the estimated heritability of Fe efficiency on a plot basis was 22 ± 7% for nutrient-solution and 10 ± 2% for field tests. The rates of observed genetic gain for Fe efficiency in the CO through C7 populations were similar for nutrientsolution and field tests. At a 10% selection intensity, the observed genetic gain was −0.05 score for nutrient-solution and −0.08 score for field tests when compared with a common field standard. The observed genetic gain was −0.14 score for nutrient solution and −0.11 score for field tests when compared with a common nutrientsolution standard.
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