Do different production environments justify separate maize breeding programs?

Abstract

Different production environments are being adopted by farmers. Therefore, allocation of resources to breeding research that targets different production environments should be continuously assessed. Agronomists should conduct extensive hybrid × production environment interaction research before recommending breeders to conduct separate breeding programs for each production environment. The lack of interactions between genotypes and production environments (e.g., tillage) would not justify conducting separate breeding programs and duplicating breeding resources. On the other hand, separate breeding programs would be necessary if cultivar rankings differ. The purpose of this paper is to review the available literature on experiments designed to test genotype × tillage interactions (GT) in maize (Zeamays L.). No-till system (NT) and conventional till system (CT) were utilized as examples of different production environments. The majority of experiments reviewed showed that there is no need to develop cultivars specific to NT because the cultivars that were developed under CT systems performed relatively the same under NT. The magnitude of GT interactions found was very small to expect better cultivars from breeding under NT. Additional research is needed to confirm these conclusions, especially when applied to other production environments (e.g., development of cultivars under organic conditions). Scientists should evaluate genotype by tillage interactions before investing additional resources in breeding for those specific target environments. Top yielding genotypes seem be consistent across years, locations, inputs; and most of the present evidence suggests that breeding for specific till systems is not necessary.