Genotype by Tillage Interactions of S1 Lines from Two Maize Synthetics1

Abstract

Hybrids presently being used for commercial production of maize (Zea mays L.) were developed and evaluated primarily in fields tilled with moldboard plows. In contrast, 37% of the commercial maize hectar age in the USA in 1984 was planted using some type of reduced tillage practice. The effects of using genotypes selected with conventional tillage in reduced tillage field environments are not known. This study evaluated 100 S1 lines from each of two different maize synthetics to examine the consequences of using different tillage systems for field evaluations. The lines were grown in five environments, over a 2‐yr period using no‐till and conventional tillage. The S1 lines from the BS22(R)C1 synthetic had few significant interactions of genotypes with tillage systems and expressed levels of genotypic variance in no‐till equal to or greater than the levels expressed in conventional tillage. The S1 lines from the BS13(SCT)C6 synthetic had significant interactions between genotypes and tillage systems for six of the eight traits reported, and expressed similar levels of genetic variance in each tillage system. Correlations between traits were similar in both tillage systems. Selection efficiency was better in no‐till than in conventional tillage for the BS22(R)C1 synthetic. No obstacles to the use of no‐till systems for evaluation and selection of maize genotypes were observed.