Genetic progress, adaptability and stability of maize cultivars for value of cultivation and use trials

Abstract

Maize breeding programs conduct multi-environment trials every year to assess the performance of new cultivars in pre-releasing tests. The data are combined across sites and seasons to perform a joint analysis in order to obtain information that will help breeders to select the best cultivars for different environments. Beyond this, it is essential to understand the different factors that can hamper the selection and genetic progress (i.e., genetic variability, selection intensity and genotype-by-environment interactions). In this study, the genetic progress (GP) was estimated and the adaptability and stability of 81 maize genotypes were evaluated in a series of trials for the value of cultivation and use (VCU) between the 2010/11 and 2014/15 growing seasons. The genotypes were composed of open-pollinated varieties, topcross hybrids, intervarietal hybrids, and single, double and three-way cross hybrids and were assessed in 117 environments in the central region of Brazil, from which 22 presented environmental stresses. For grain yield, an annual GP of 331.5 kg ha-1 was observed, thus showing efficiency in the selection of superior cultivars. Additionally, it was observed that some low-cost seed cultivars showed yield potential, adaptability and stability estimates that were compatible with commercial hybrids, thus making them quite attractive for cultivation in environments with or without abiotic stresses.

Economic analysis of maize production as a function of theorical speed of the tractor-seeder set and the sowing site

“…The experiment was carried out in the period corresponding to the second harvest in the state, that is, the period in which there is little rain, and the incidence of sunlight is very intense. The good results found in this work can also be related to the interception of solar radiation by the leaves of corn plants, which directly influences grain yield (Uate 2016).…”

Yield stability of common bean genotypes in the state of Santa Catarina, Brazil

“…The junction of the location and the seasons (rainy, or dry) likely contributed also, but this is not a relevant factor, since the possible new common bean cultivar can be recommended for both growing seasons. For maize, the recommendation has a clear separation for the rainy and dry growing season (Uate et al, 2019). The analysis of stability and productivity is essential when a GxE is detected.…”

Progresso genético do programa de melhoramento de variedades de milho da Embrapa no Acre

“…A taxa de renovação de tratamentos nos ensaios, de certo modo, reflete a eficiência do programa de melhoramento. Uma taxa média de 50% e 25% nos anos intermediários sugere uma atividade moderada dentro do programa de melhoramento, embora inferior a verificada por Vencovsky et al, (1986) estimada em 61% para milho é superior a pesquisa de Uate et al, (2019) que estimou em 31% pelo valor genotípico (ou BLUP). A taxa de manutenção nos anos intermediários de 37.7% no ano dois e 60%…”

“…A finalidade é quantificar a eficiência e auxiliar nos ajustes necessários, a fim de gerar economia de recursos e definições estratégicas dentro do programa. Uate et al (2019) Campos (2019) estimaram o progresso genético para componentes da produção, suas características fenotípicas e a produtividade de grãos de soja. Vencovsky et al, (1986) desenvolveram um método e estimaram o ganho genético, em cada par de anos consecutivos (biênio), com base nos resultados das médias de produtividade das cultivares obtidas nos ensaios de competição, para saber se a troca de cultivares, de um ano para outro, resulta em ganho de produtividade.…”