Effect of Visual Selection During the Development of Inbred Lines of Maize

Abstract

The pedigree method of breeding with visual selection for plant and/or ear appearance has been traditionally used in maize (Zea mays L.) breeding. We evaluated 121 F2:3 families for plant and ear appearance as well as for several objectively measured traits and estimated the heritability of the traits and the genetic correlations between them. Heritability was greater than zero for most traits and the genetic correlation between the intuitive selection indexes and several of the objective traits were moderate or even high. Based on these results we predicted that selection based on intuitive selection indices would improve several characteristics of the inbred lines simultaneously. To confirm this we developed 20 inbred lines using pedigree selection with visual per se selection (VPSS) and 20 inbred lines without selection. The selected inbreds had a higher average value than the unselected lines for several traits across different environments; for example, the selected lines were 17 cm taller and yielded 0.3 Mg ha−1 more than the unselected inbreds. Furthermore, testcrosses of the selected lines were, on average, taller and yielded about 0.5 Mg ha−1 more than testcrosses of the unselected lines. We conclude that, under certain conditions, VPSS can achieve a high effectiveness improving both the performance of the lines and the yield of their hybrids