Contribution of population improvement to the development of maize lines with commercial value

Abstract

The grain yield was increased by 8.2% per cycle (32.8% overall) in a population of Mindszentpusztai Yellow Dent (MYD), by 8.9% per cycle (35.6% overall) in a population of Mv Syn. I and by 4.9% per cycle (19.7% overall) in a population of Westigua when tested on the closed pedigree line HMv 124-2. Averaged over the three populations the rise in grain yield was 7.5% per cycle, giving a total of around 30% after four cycles. The grain moisture at harvest showed a slight but significant decrease, while there was no change in the percentage stalk lodging. It seems probable that this increase in grain yield was achieved not at the expense of other correlated characters, but as the result of a greater frequency of gene combinations having a positive effect on grain yield, since recurrent selection was combined with selection for multiple ears at high plant density. The hybrid performance of the improved populations was extremely good, reaching 87.9% of that of commercial hybrids. Over the last 25 years around 11,500 S1 families have been tested from a total of 115 populations (including the three discussed above) and the inbreeding of the selected families was continued until the homozygous state was reached. Despite careful selection, it has not proved possible to breed inbred lines suitable for the development of hybrids with commercial value. Further research will be required to discover the reasons for this failure.