Selection for Agronomically Acceptable Inbred Lines in Adapted × Exotic Sorghum Backcross Populations
- Abebe Menkir,
- P. J. Bramel-Cox and
- M. D. Witt
The correlation between yield and other undesirable agronomic traits in sorghum (Sorghum bicolor (L.) Moench) may limit the isolation of suitable inbred lines from adapted × exotic backcrosses. The objective of this study was to compare use of a rank summation index with independent culling when trying to select agronomically acceptable lines from progeny of matings between three exotic accessions and two adapted parents, an inbred line, and a broad-based population. Phenotypic correlations among yield, plant height, days to flowering, and seed weight were generally low (r < ±0.50). Selection for yield alone resulted in lines with increased height and days to flowering. The number of agronomically acceptable lines derived from two of the three matings of the adapted population (KP9B) by using independent culling levels was greater than the number derived from the corresponding matings of the adapted inbred line (CK60). Also, with the use of rank summation index scores, KP9B matings gave a higher number of acceptable lines than did corresponding CK60 matings. Mean yields and seed weights of the top-scoring 10 lines selected by using the rank summation index were either comparable with or better than the means of their respective adapted parent. In most instances, selections were earlier flowering and slightly taller than then' adapted parent. Overall, backcrossing to an adapted population enhanced the utilization of exotic accessions more than backcrossing to an adapted inbred line. Selection for agronomic acceptability within introgressed populations was effective by using rank summation index and independent culling.
Copyright © 1994.