Abstract
The implementation of a network of maize trials is an onerous task, so breeding programs seek to eliminate redundant environments, remaining only contrasting ones. The objective was to perform the homogeneous environment grouping by studying the G×E interaction through different environmental stratification methods, as well as to compare the efficiency of these methods. Four methods were used: environmental dissimilarity (Djj); Decomposition of the genotype × environment interaction (G×E) into simple and complex parts by Cruz and Castoldi; Pearson correlation coefficient; and factor analysis. Twenty-five single-cross corn hybrids and three commercial cultivars were tested in eight cultivation environments in a randomized complete block design with three replicates in the evaluation of grain yield. Quedas do Iguaçu and Cascavel can be reduced into only one test environment by methods of factor analysis and Pearson correlation. The environments of Pato Branco and Ampére are grouped by two of the four methods employed. However, Clevelândia, Londrina, and Coxilha do not group with other environments in three of the four methods, and Itapiranga in two of the four methods. Cruz and Castoldi’s method and stratification by factor analysis are more rigorous in grouping criteria.
Highlights
Corn, due to its nutritional value, adaptation to different edaphoclimatic conditions and high yields achievable, is one of the most cultivated cereals in the world, showing great social and economic importance
The average grain yield in the plot (GY) was between 10.69 kg for Clevelândia and 5.39 kg for Londrina, with a general average of 8.09 kg, revealing great variation in the conditions under which the tests were conducted. This fact can be attributed, in part, to the geographic heterogeneity of the analyzed environments, with altitudes ranging from 190 to 960 m, latitude 23o19′39′′ to 28o07′38′′ S, and longitude of 51o07′47′′ to 53o42′07′′ W, respectively, it certainly reveals climatic differences among the environments used for the tests, due to the differences among the environments, when verifying the values of the mean square residue (MSR), it can be verified that the relation among the higher and lower values of this parameter, was equal to 4.43
Quedas do Iguaçu and Cascavel can be reduced to only one test environment by Pearson correlation and factor analysis methods
Summary
Due to its nutritional value, adaptation to different edaphoclimatic conditions and high yields achievable, is one of the most cultivated cereals in the world, showing great social and economic importance. It is worth noting the great increase in the employment of labor in the rural and urban areas, due to its participation as raw material for more than 500 industrial segments and highlighting the production chain of biofuels (Duete et al, 2009; Carvalho et al, 2015). The cultivated plants are submitted to the most different cultivation conditions These variations may be due to soil fertility, temperature, precipitation, rainfall among other factors. Breeders are required to evaluate their cultivars and/or lineages in experiments conducted at various locations and/or agricultural crops (Ramalho et al, 2012)
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