Abstract
ABSTRACT: The potential expression of crop productivity is a constant challenge for plant breeders in the face of oscillations in environmental variables, making selection difficult and increasing the operational and methodological costs in obtaining the ideal cultivar for a determined region. The objective of the research was to investigate the effects of genotype x environment interaction in the selection of cowpea lines with high grain yield, adaptability, and genotypic stability simultaneously, in environments of the Northwest region of Rio de Janeiro State, using mixed models (Maximum Restricted Likelihood - REML/Best Linear Unbiased Prediction - BLUP). 27 cowpea genotypes were evaluated in six environments by combining location (Cambuci-RJ and Bom Jesus do Itabapoana-RJ) and year (2016, 2017 and 2018). A randomized block design with four replications was performed. The genetic parameters were estimated via the REML/BLUP procedure, and the selection was based on the harmonic mean method of the relative performance of the genetic values (HMRPGV). A meaningful difference was observed for environment and genotype x environment interaction. The residual variance and the variance of the genotype x environment interaction formed the most significant fractions of the phenotypic variance. Lines 4 (Bico-de-ouro 1-5-24), 6 (Pingo-de-Ouro 1-5-4), 5 (Pingo-de-Ouro 1-5-26), and 9 (Pingo-de-Ouro 1-5-8), stood out as superior in terms of stability and adaptability and grain yield by HMRPGV. Commercial cultivars 13 (BRS-Tumucumaque) and 26 (BRS-Itaim) had high grain yield, adaptability, and specific stability in the evaluated edaphoclimatic conditions.
Highlights
The cowpea (Vigna unguiculata (L.) Walp.), is a widely adaptable species, high productive capacity, rich in vitamins and minerals and abundant genetic variability (FREIRE FILHO, 2011)
There was no significant difference as considering the genotype as a source of variation (Table 2). These results demonstrate that the potential grain yield and grain production of the cowpea strains did not differ genetically and, did not show a differential response in the environments in the region where the tests were performed
The individual phenotypic variance is composed by the computation of the genotypic variance, the residual variation between plots and the variation of the genotype x environment interaction (CARVALHO et al, 2016)
Summary
The cowpea (Vigna unguiculata (L.) Walp.), is a widely adaptable species, high productive capacity, rich in vitamins and minerals and abundant genetic variability (FREIRE FILHO, 2011). It is a culture of great current and strategic potential, with an excellent perspective on the international market, as it is staple food in more than 65 countries (SINGH et al.,2002; FREIRE FILHO et al.,2011). Its cultivation occupies an area of approximately one million hectares throughout the national territory, with the North and Northeast. Second FAO (2018), world production of cowpea is approximately 7 million tons, produced on 12.4 million hectares. The Midwest, CenterSouth, Southeast and North regions have the highest production, due to its large-scale cultivation, making use of advanced technologies, notably in the offseason of other crops (RODRIGUES et al, 2017; CONAB, 2018)
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