Principles of Plant Genetics and Breeding

Summer Year 5
Summer Year 7
Summer Year 8
Visual hybrid
Comprehensive hybrid
and line evaluation
Comprehensive hybrid
and line evaluation
A3 testcross
hybrids
BREEDING SORGHUM 515
Selection based on
A3 hybrid performance
Advanced
hybrids
Advanced
hybrids
Figure 4 The advanced testing and sterilization scheme used by the TAES sorghum breeding program at College
Station, Texas. From the F 5 generation (see Figure 2), testcrossed hybrids and BC 0 sterilization lines are grown for
evaluation and continued backcrossing. If testcross performance is acceptable, sterilization is continued through
backcrossing until the A-line is identical in phenotype to the B-line. As the A-line becomes available, additional
hybrid evaluation is performed to confirm heterosis and line acceptability. The R-line testcross evaluation process is
similar but eliminates the requirement of sterilization.
References
Selection on hybrid
performance and
inbred acceptability
BC 0
BC 1
BC × F 1
Release
Sterilization back to B-line
Score sterility
Advance best pairs
Use same approach in all
Sterilization back to B-line
Score sterility
Advance best pairs
Testcross to R-line testers
Advance best pairs
Testcross to R-line
FAO. 2001. Available at 222.fao.org.
Rooney, W.L. 2003a. Registration of Tx2912 to Tx2920 sorghum germplasm. Crop Sci. 43:442–443.
Rooney, W.L. 2003b. Registration of Tx2921 to Tx2928 sorghum germplasm. Crop Sci. 43:443–444.
Rooney, W.L. 2004. A overview of sorghum breeding methodology. Adv. Agron. 83:37–109.
Common breeding methods
Early sorghum improvement depended on introductions.
The introduction of short-day germplasm from
the tropical regions into temperate regions with a longer
photoperiod was unsuitable for commercial production
because they usually matured too late or were too tall.
Using backcrossing, US Department of Agriculture
(USDA) and Texas A&M University researchers
BC 2
BC 3
BC 4
Summer Year 5
Winter Year 5
Summer Year 6
Winter Year 6
Summer Year 7
embarked on the sorghum conversion program to
convert tropical varieties to temperate climate-adapted
cultivars by substituting two recessive alleles for the
dominant height alleles in the tropical varieties, as
well as the recessive mal maturity alleles for the Mal
dominant counterparts.
Pure-line selections have been made in many countries
in Africa and India. Pedigree selection is commonly
used following hybridization. The population