| The quantification of the breeding value of sources of alleles for line improvement and the relationship of these sources to the heterotic groups used in hybrid production are major challenges in plant breeding. Also, the identification of valuable materials as early in the developmental process as possible is desirable, in order that less time and resources are spent on inferior materials. Studies of this nature have been under consideration in sorghum for a number of years but were held up by the difficulty of producing crossed seed in quantity on normally fertile testers. For example, in order to evaluate potential female parents, the B-line had to be converted through extensive backcrossing to a male-sterile A-line. The discovery of several new cytoplasmic male-sterility systems in which normal pollinator lines could be male-sterilized made testers available for the production of test hybrids.;A study was conducted to evaluate these new breeding methods. A diverse group of sterile R-line testers were crossed to an equally diverse group of B-lines. Evaluations were made regarding the effectiveness of early generation testing, general and specific combining ability, and quantitative analysis regarding favorable alleles and heterotic grouping when sorghum maintainer lines were crossed to the sterile R-lines.;Significant correlations ranging from.58 to.67 were found between hybrids developed from early and late generation material. Line yields compared to line in hybrid yields were significantly correlated (.60) in selected and advanced lines, but were uncorrelated in random selections. In addition, the genetic evaluation analysis procedure was found to be useful to identify donors with higher favorable dominant alleles and to provide a classification system of heterotic group. |
