Comparison of conventional and male-sterile facilitated breeding methods for increasing seed yield in soybean

Plant breeders are continuously searching for more effective and efficient breeding procedures. Two alternative breeding methods for increasing seed yield and other characters in soybean were compared. The conventional breeding (CB) method used ten elite parents in a partial diallel mating to produce 45 single-cross populations. In the male-sterile breeding (MSB) method, the same ten elite parents were mated as males to $ms\sb2ms\sb2$ male-sterile F$\sb2$ plants of a soybean population. Each year, ten new parents were selected. A diallel mating was performed for the conventional procedure, while the same ten parents were intermated to F$\sb2$ progeny of the population formed in the preceding MSB cycle. Data from a replicated yield test of 100 random F$\sb5$-derived lines from the first cycle of each procedure, and 100 random F$\sb6$-derived lines from a second cycle of both methods were studied. For data averaged over both cycles, the CB populations yielded 74.0 Kg ha$\sp{-1}$ more than those of the MSB populations with no significant differences between populations of both method for content of protein and oil, 100-seed weight, maturity, lodging score, and plant height. Mixed results were found, however, when comparing both methods using individual cycle data for all characters under consideration. Choice of MSB or the CB depends on the breeding objective and the facilities available. For short term genetic gain, regardless of costs involved, the CB method appeared to be more desirable than MSB. But for other breeding objectives, the use of broad genetic base populations, as well as cost efficiency, convenience, and flexibility advantages of the MSB method make it a worthy alternative to the current soybean breeding procedures