Adaptability, stability and environmental stratification of genetically and nongenetically modified corn in the Cerrado/Adaptabilidade, estabilidade e estratificação ambiental de milho transgênico e não transgênico no Cerrado

Crop yield depends on interaction between genetic and environmental factors, making it essential to study adaptability, stability and environmental stratification in order to mitigate the effects of this interaction. Four experiments were conducted to assess competition between corn cultivars in the 2018/19 growing season, two in Paraíso do Tocantins and two in Palmas, with sowing performed on November 5, 2018 and January 15, 2019. Cultivar-environment interaction was analyzed in genetically modified (GM) and non-GM commercial corn cultivars in the Vale do Araguaia region of Tocantins state (TO), Brazil, A randomized block design was used for all the experiments, in 3 X 12 factorial scheme, with three doses of nitrogen fertilizer as topdressing (50, 100 and 150 kg of N [ha.sup.-1]) and 12 commercial cultivars (six non-GM, 1CHD, 2CV, 3CV, 4CV, 5CTH, 6CDHand six GM, 7GTH, 8GTH, 9GSH, 10GSH, 11GSH, 12GSH. For statistical analysis, the N dose in each experiment represented a different environment. The characteristic studied was grain yield, using the adaptability and stability methods as well as environmental stratification. Different responses were observed between the GM and non-GM cultivars. Most of the GM and non-GM cultivars were better adapted to favorable and unfavorable environments, respectively. All the environments exhibited similar behavior regardless of location, sowing time and the N dose used, demonstrating that fewer environments can be used in future breeding research. Key words: Zea mays L., cultivar x environment interaction, grain yield O rendimento da cultura depende da interação entre os fatores genéticos e ambientais, tornando-se necessário estudo de adaptabilidade, estabilidade e estratificação ambiental visando atenuar os efeitos desta interação. Neste sentido, visando estudar a interação cultivar x ambiente em cultivares comerciais de milho transgênico e não transgênico na região do Vale do Araguaia TO, foram realizados quatro ensaios de competição de cultivares implantados na safra 2018/19, sendo dois em Paraíso do Tocantins e dois em Palmas, com semeaduras realizadas em 05/11/2018 e 15/01/2019. O delineamento experimental, em cada ensaio, foi de blocos casualizados com 36 tratamentos, que foram dispostos em esquema fatorial 3 x 12, representados por três doses de adubação nitrogenada em cobertura (50, 100 e 150 kg de N [ha.sup.-1]) e por 12 cultivares comerciais, (seis transgênicos: 1CHD, 2CV, 3CV, 4CV, 5CTH, 6CDH e seis não transgê