Adaptabilidade e estabilidade de híbridos de milho transgênicos na safrinha subtropical

Abstract

Corn is cultivated in a wide territorial extension and, generally, the manifestation of the phenotype is highly influenced by the environment. For obtaining superior genotypes it is necessary to install Multiple Trials (MET). By means of these trials, it is possible to study the genotype x environment interaction (GE), aiming at selecting genotypes with wide production adaptability and stability, in order to meet the demands of the producers in the many regions. The approach using mixed models provides more accurate and precise estimates for aiding the breeders in the selection of the best genotypes, especially under variance unbalance and heterogeneity, which is common in METs. This work was conducted with the objective of evaluating the adaptability and stability of grain production (kg ha -1 ) in transgenic corn hybrids for the planting conditions of subtropical interim-harvest in the states of Mato Grosso do Sul (MS), Paraná (PR) and São Paulo (SP), Brazil. Two Value for Cultivation and Use (VCU) trials were conducted using hybrids with different transgenic events. The first VCU trial, PRO 2, consisted of 20 pre -commercial simple hybrids with YieldGard VT PRO2 ® technology and eight commercial hybrids as witness. The second VCU trial, HERCULEX (HX), consisted of 24 pre-commercial hybrids with Herculex ® technology and 11 commercial hybrids as witness. In total, we evaluated 47 trials, distributed into 24 municipalities, in the agricultural year of 2013. The hybrids from both VCU were evaluated in a completely randomized blocks design, with two replicates. We detected interaction between the hybrids and the different environments by the LRT test (alfa = 0.05). With the interaction verified, we proceeded to the analysis of adaptability and stability using the GGE Biplot method, to widen the understanding of the inter-relation between hybrids and environments. We verified that some of the environments presented similar results, being grouped into mega-environments. The grouping varied when comparing the VCUs. Hybrids CD 384HX, 20A55HX and DKB 330PRO2 presented the highest grain production in VCU PRO 2. In VCU HX, hybrids P 30F53H, DKB 390PRO and P 3161H were highlighted with the best performances. These hybrids combine high grain production and high stability in the environments evaluated. Environments A6 (Rio Brilhante/MS) and A19 (Santa Helena/PR) most discriminated the hybrids, being fundamental to conducting VCUs for the selection of superior hybrids.