# ABSTRACT

The effects of the genotype × environment interaction can be reduced by using cultivars with high adaptability and good yield stability. Studies on this subject allow identification of genotypes of predictable behavior, and responsive to environmental variations in specific and general conditions, in favorable or unfavorable environments. The objective of this work was to evaluate the adaptability and phenotypic stability of cowpea elite lines of semi-prostrate growth habit in the Cerrado biome in Brazil. Twenty cowpea genotypes of semi-prostrate growth habit were evaluated in nine VCU (value for cultivation and use) tests from 2010 to 2012. Grain yield data were subjected to analysis of variance, and stability and adaptability analyses were carried out by the methods of Eberhart and Russell (1966), Lin and Binns (1988) (modified), Wricke (1965), and Annicchiarico (1992). The method of Wricke (1965) was not very descriptive, since it indicates only the contribution of each genotype to the genotype × environment interaction. The results obtained by the methods of Lin and Binns (1988) (modified), Annicchiarico (1992) and Eberhart and Russell (1966) were more descriptive, and similar in indicating the most promising cultivar (BRS-Xiquexique) and lines (Pingo-de-Ouro-1-2, MNC02-676F-1, MNC01-649F-2-1 and MNC02-677F-2). These lines have potential for the development of new cultivars because they present adaptability and yield stability in the Cerrado biome of Brazil.

Key words:
Vigna unguiculata; Genotype × Environment Interaction; Grain yield

# RESUMO

Palavras-chave:
Vigna unguiculata; Interação Genótipos × Ambientes; Produtividade de Grãos

# INTRODUCTION

Cowpea [Vigna unguiculata (L.) Walp] is cultivated in the Northeast, North and Center-West regions of Brazil. However, the average productivity of cowpea crops varies greatly among different regions, mainly due to environmental variations and the use of genetic materials that are not very productive or with undesirable characteristics (FREIRE FILHO et al., 2011FREIRE FILHO, F. R. et al. Feijão-caupi: produção, melhoramento genético, avanços e desafios. Brasília, DF: Embrapa Informação Tecnológica, 2011. 81 p.).

One of the main challenges in genetic improvement of species is to understand genotype × environments interaction (G×E), which is assessed by the evaluation of the genotypes in different environments (CRUZ; CARNEIRO; REGAZZI, 2014CRUZ, C. D.; CARNEIRO, P. C. S.; REGAZZI, A. J. Modelos biométricos aplicados ao melhoramento genético. 3. ed. Viçosa, MG: UFV, 2014. 668 p. v. 2.). The evaluation of G×E is very important because of the possibilities of genotypes behave differently in different environments due to G×E (RESENDE; DUARTE, 2007RESENDE, M. D. V.; DUARTE, J. B. Precisão e controle de qualidade em experimentos de avaliação de cultivares. Pesquisa Agropecuária Tropical, v. 37, n. 3, p. 182-194, 2007.). This behavior affects the selection gain and makes it difficult to recommend cultivars with wide adaptability.

There are several methods to evaluate the G×E and to determine the adaptability and yield stability of the cultivars. According to the Eberhart and Russell (1966)EBERHART, S. A.; RUSSELL, W. A. Stability parameters for comparing varieties. Crop Science, v. 6, n. 1, p. 36-40, 1966. method, based on simple linear regression, an ideal cultivar presents overall adaptability and stability while maintaining a good performance when the environmental conditions are unfavorable. However, when the data do not fulfill the assumptions of the regression analysis, an alternative would be the use of non-parametric analyzes such as the method of Lin and Binns (1988)LIN, C. S.; BINNS, M. R. A. Superiority measure of cultivar performance for cultivars x location data. Canadian Journal of Plant Science, v. 68, n. 1, p. 193-198, 1988. (modified) described by Cruz, Carneiro and Regazzi (2014)CRUZ, C. D.; CARNEIRO, P. C. S.; REGAZZI, A. J. Modelos biométricos aplicados ao melhoramento genético. 3. ed. Viçosa, MG: UFV, 2014. 668 p. v. 2.. This method allows the identification of the most stable genotypes by a single parameter of stability and adaptability, and includes the deviations in relation to the maximum yield obtained in each environment; making it possible to detail this information for favorable and unfavorable environments. Other examples are the method of Annicchiarico (1992)ANNICCHIARICO, P. Cultivar adaptation and recommendation from alfafa trials in Northern Italy. Journal of Genetics and Plant Breeding, v. 46, n. 3, p. 269-278, 1992., which presents an easy application and is based on the estimation of a risk index for the recommendation of a given cultivar; and the method of Wricke (1965)WRICKE, G. Zur berechüng der okovalenz bei sommerweizen und hafer. Zeitschrisft fuer Pflanzezuchtung, v. 52, n.1, p. 127-138, 1965., called ecovalence, which is estimated by the distribution of the sum of squares of the G×E into parts due to single genotypes. This method has an easy interpretation; however, the data need to be balanced to meet the assumptions of a regression analysis (CARVALHO et al., 2016CARVALHO, L. C. B. et al. Evolution of methodology for the study of adaptability and stability in cultivated species. African Journal of Agricultural Research, v. 11, n. 12, p. 990-1000, 2016.).

Choosing the method to characterize genotypes regarding adaptability and stability depends on the available experimental data, the required precision, and the type of information desired by the breeder (CRUZ; CARNEIRO; REGAZZI, 2014CRUZ, C. D.; CARNEIRO, P. C. S.; REGAZZI, A. J. Modelos biométricos aplicados ao melhoramento genético. 3. ed. Viçosa, MG: UFV, 2014. 668 p. v. 2.). Each one of these methods has peculiarities that can contribute to improve the analysis; and in some cases, these methods may be complementary to each other, therefore, it is important to use more than one method (PEREIRA et al., 2009PEREIRA, H. S. et al. Adaptabilidade e estabilidade de genótipos de feijoeiro-comum com grãos tipo carioca na Região Central do Brasil. Pesquisa Agropecuária Brasileira, v. 44, n. 1, p. 29-37, 2009.). In this context, the objective of this study was to evaluate the adaptability and phenotypic stability of cowpea elite lines of semi-prostrate growth habit in the Cerrado biome in Brazil.

# MATERIAL AND METHODS

Twenty cowpea genotypes of semi-prostrate growth habit from VCU (value for cultivation and use) tests were evaluated, where fifteen lines were from the Embrapa Mid-North Cowpea Breeding Program and five were commercial cultivars (Table 1). Nine experiments were conducted under rainfed conditions, in the 2010, 2011 and 2012 crop seasons, in three locations: Balsas and São Raimundo das Mangabeiras in the State of Maranhão (MA), and Primavera do Leste in the state of Mato Grosso (MT) (Table 2).

Table 1
Cowpea genotypes of semi-prostrate growth habit evaluated in nine experiments conducted in Balsas MA, São Raimundo das Mangabeiras MA, and Primavera do Leste MT, in the 2010, 2011 and 2012 crop seasons
Table 2
Geographic coordinates, average annual precipitation and soil class of the sites used for nine experiments conducted in Balsas MA, São Raimundo das Mangabeiras MA, and Primavera do Leste MT, in the 2010, 2011 and 2012 crop seasons

All experiments were conducted in a complete randomized block experimental design with four replications. The randomization was performed individually for each environment. The plots of the experiments consisted of four 5.0-meter rows spaced 0.80 m apart, with 0.25 m between plants, and the evaluation area consisted of the two central rows. Weed, pest and disease control was carried out according to the recommendations for cowpea (FREIRE FILHO; LIMA; RIBEIRO, 2005FREIRE FILHO, F. R.; LIMA, J. A. A.; RIBEIRO, V. Q. Feijão-caupi: avanços tecnológicos. Brasília: Embrapa Informação Tecnológica, 2005. 519 p.).

The statistical analysis was carried out assuming that each combination of years with locations represents an environment, making nine environments. The yield data were subjected to analysis of variance, considering the mixed model with effect of treatments as fixed and the others as random. A joint analysis of the environments was performed after evaluating the homogeneity of the residual variances. According to Pimentel-Gomes (2000)PIMENTEL-GOMES, F. Curso de estatística experimental. São Paulo: Nobel, 2000. 466 p., if the ratio between the largest and the smallest mean square of the residue is less than seven, the residual variances are homogeneous. However, due to the lack of homogeneity of variance, the degrees of freedom of the mean error and the G×E were adjusted according to the method of Cochran (1954)COCHRAN, W. G. The combination of estimates from different experiments. Biometrics, v. 10, n. 1, p. 101-129, 1954.. The Scott-Knott test at 5% probability was used to identify the existence of homogeneous groups, by minimizing the variation within, and maximizing between groups.

The evaluation of genotype adaptability and stability was performed using the following methods: Eberhart and Russell (1966)EBERHART, S. A.; RUSSELL, W. A. Stability parameters for comparing varieties. Crop Science, v. 6, n. 1, p. 36-40, 1966., Lin and Binns (1988)LIN, C. S.; BINNS, M. R. A. Superiority measure of cultivar performance for cultivars x location data. Canadian Journal of Plant Science, v. 68, n. 1, p. 193-198, 1988. (modified) (CRUZ; CARNEIRO; REGAZZI, 2014CRUZ, C. D.; CARNEIRO, P. C. S.; REGAZZI, A. J. Modelos biométricos aplicados ao melhoramento genético. 3. ed. Viçosa, MG: UFV, 2014. 668 p. v. 2.), Wricke (1965)WRICKE, G. Zur berechüng der okovalenz bei sommerweizen und hafer. Zeitschrisft fuer Pflanzezuchtung, v. 52, n.1, p. 127-138, 1965. and Annicchiarico (1992)ANNICCHIARICO, P. Cultivar adaptation and recommendation from alfafa trials in Northern Italy. Journal of Genetics and Plant Breeding, v. 46, n. 3, p. 269-278, 1992..

In the method of Eberhart and Russell (1966)EBERHART, S. A.; RUSSELL, W. A. Stability parameters for comparing varieties. Crop Science, v. 6, n. 1, p. 36-40, 1966., the adaptability was given by the estimation of the parameter β1i and by the average yield β0i; and the stability by the variance of the regression deviations δĳ, according to the following model Yĳ = β0i + β1iIj + δĳ + Σĳ, where: Yĳ is the average grain yield (kg ha-1) of genotype . in environment . ; β0i is the overall mean; β1i is the linear regression coefficient; . j is the environmental index; δĳ is the variance of the regression deviations; and Σĳ is the mean experimental error.

According to the method of Lin and Binns (1988)LIN, C. S.; BINNS, M. R. A. Superiority measure of cultivar performance for cultivars x location data. Canadian Journal of Plant Science, v. 68, n. 1, p. 193-198, 1988. (modified) described by Cruz, Carneiro and Regazzi (201)4CRUZ, C. D.; CARNEIRO, P. C. S.; REGAZZI, A. J. Modelos biométricos aplicados ao melhoramento genético. 3. ed. Viçosa, MG: UFV, 2014. 668 p. v. 2., the decomposition of Pi in the parts related to favorable and unfavorable environments was performed. The estimate of Pi was given by the equation: $Pi=∑j=1nYij−Mj2x$, where: Pi is the estimation of the adaptability and stability of the genotype i ; Yĳ is the yield of the genotype i in the environment j; Mj is the maximum observed response among all genotypes in the j environment; and α is the number of environments.

In the Annicchiarico method (1992)ANNICCHIARICO, P. Cultivar adaptation and recommendation from alfafa trials in Northern Italy. Journal of Genetics and Plant Breeding, v. 46, n. 3, p. 269-278, 1992., the confidence index Ii was calculated for the favorable and unfavorable environments according to the equation: Ii = Ȳi - Z(1-α)Si, wherein Ȳi is the overall mean of genotype . in percentage; Z is the percentile (1-α) of the cumulative normal distribution function; α is the level of significance; and Si is the standard deviation of the percentage values. The coefficient of confidence was 75%, i.e., α = 0.25.

The stability parameter proposed by Wricke (1965)WRICKE, G. Zur berechüng der okovalenz bei sommerweizen und hafer. Zeitschrisft fuer Pflanzezuchtung, v. 52, n.1, p. 127-138, 1965. was estimated using the statistic ωi, through the equation: ωi = rΣfĜA2IJ = rΣf(Yij - Ȳi. - Ȳ.i + Ȳ..)2 , where: Yij is the mean of the genotype i in the environment j ; Ȳi. is the mean of genotype i ; Ȳ.i is the mean of the environment j ; and Ȳ.. is the overall mean.

The individual and joint analysis of variance, and tests of comparison of means, stability and adaptability were performed using the software GENES (CRUZ, 2013CRUZ, C. D. Genes: a software package for analysis in experimental statistics and quantitative genetics. Acta Scientiarum Agronomy, v. 35, n. 3, p. 271-276, 2013.).

# RESULTS AND DISCUSSION

The genotypes presented significant differences (p <0.05) by the analysis of individual variances, in all environments, except Balsas in 2010 (Table 3). This result denotes genetic variability among the genotypes evaluated, which is essential to proceed with the genotype selection process.

Table 3
Individual analysis of variance of the grain yield (GY) of 20 cowpea genotypes of semi-prostrate growth habit evaluated in nine experiments conducted in Balsas MA, São Raimundo das Mangabeiras MA, and Primavera do Leste MT, in the 2010, 2011 and 2012 crop seasons

The coefficient of variation (CV) of the experiments evaluated ranged from 13.85 to 36.10% (Table 3). The means and CV of the tests varied, denoting the different conditions to which the genotypes were subjected. The coefficient of variation (CV) is an estimate of the experimental error of the overall mean of the test, and an indication of the experimental accuracy. According to Pimentel-Gomes (2000)PIMENTEL-GOMES, F. Curso de estatística experimental. São Paulo: Nobel, 2000. 466 p., observed CV can be classified as low (lower than 10%), average (10% to 20%), high (20% to 30%), and very high (higher than 30%). The CV values found in this work were within the range found in other studies on cowpea, such as Barros et al. (2013)BARROS, M. A. et al. Adaptabilidade e estabilidade produtiva de feijão-caupi de porte semiprostrado. Pesquisa Agropecuária Brasileira, v. 48, n. 4, p. 403-410, 2013., Benvindo et al. (2010)BENVINDO, R. N. et al. Avaliação de genótipos de feijão-caupi de porte semi-prostrado em cultivo de sequeiro e irrigado. Comunicata Scientiae, v. 1, n. 1, p. 23-28, 2010., Bertini, Teófilo and Dias (2009)BERTINI, C. H. C. M.; TEÓFILO, E. M.; DIAS, F. T. C. Divergência genética entre acessos de feijão-caupi do banco de germoplasma da UFC. Revista Ciência Agronômica, v. 40, n. 1, p. 99-105, 2009., and Silva and Neves (2011)SILVA, J. A. L.; NEVES, J. A. Produção de feijão-caupi semi-prostrado em cultivos de sequeiro e irrigado. Revista Brasileira de Ciências Agrárias, v. 6, n. 1, p. 29-36, 2011..

The joint analysis of variance showed significant differences (. <0.01) for the sources of variation of environments, genotypes, and G×E (Table 4). The significant effect of the G×E indicates the different response of the genotypes to the environments, thus requiring analyzes of adaptability and phenotypic stability.

Table 4
Joint analysis of variance of the grain yield (kg ha-1) of 20 cowpea genotypes of semi-prostrate growth habit evaluated in nine experiments conducted in Balsas MA, São Raimundo das Mangabeiras MA, and Primavera do Leste MT, in the 2010, 2011 and 2012 crop seasons

The grain yield of the genotypes presented homogeneous groups by the Scott-Knott test (p <0.05) (Table 5). The edaphoclimatic conditions of São Raimundo das Mangabeiras MA, affected the performance of the genotypes, decreasing their productive performance. Regarding the average grain yield, the line MNC02-701F-2 (1451.20 kg ha-1) and the cultivar BRS-Xiquexique (1439.60 kg ha-1)-both from the branco commercial subclass-stood out from the others, presenting promising yields, with good adaptation to the edaphoclimatic conditions of the cerrado biome in Maranhão. However, the overall average yield found in this study (1226.60 kg ha-1) is lower than the averages found by Teixeira et al. (2010)TEIXEIRA, I. T. et al. Desempenho agronômico e qualidade de sementes de cultivares de feijão-caupi na região do cerrado. Revista Ciência Agronômica, v. 41, n. 2, p. 300-307, 2010. (1307.00 kg ha-1) and Silva and Neves (2011)SILVA, J. A. L.; NEVES, J. A. Produção de feijão-caupi semi-prostrado em cultivos de sequeiro e irrigado. Revista Brasileira de Ciências Agrárias, v. 6, n. 1, p. 29-36, 2011. (1436.35 kg ha-1) in cowpea crops also in the Cerrado biome.

Table 5
Estimates of adaptability and phenotypic stability by the methods of Eberhart and Russel (1966)EBERHART, S. A.; RUSSELL, W. A. Stability parameters for comparing varieties. Crop Science, v. 6, n. 1, p. 36-40, 1966. and Wricke (1965)WRICKE, G. Zur berechüng der okovalenz bei sommerweizen und hafer. Zeitschrisft fuer Pflanzezuchtung, v. 52, n.1, p. 127-138, 1965. for 20 cowpea genotypes of semi-prostrate growth habit evaluated in nine experiments conducted in Balsas MA, São Raimundo das Mangabeiras MA, and Primavera do Leste MT, in the 2010, 2011 and 2012 crop seasons

The regression coefficient (β1i = 1) of the model proposed by Eberhart and Russell (1966)EBERHART, S. A.; RUSSELL, W. A. Stability parameters for comparing varieties. Crop Science, v. 6, n. 1, p. 36-40, 1966., measures the adaptability of the genotypes, and the stability of their behavior is measured by the variance of regression deviations (σ2di = 0) and by the coefficient of determination (R2). According to Cruz, Carneiro and Regazzi (2012)CRUZ, C. D.; REGAZZI, A. J.; CARNEIRO, P. C. S. Modelos biométricos aplicados ao melhoramento genético. 4. ed. Viçosa, MG: UFV , 2012. 514 p. v. 1., the R2 assists in the evaluation of stability, when the σ2di are significant. The lines MNC02-676F-1, MNC01-649F-2-1, MNC02-677F-2 and Pingo-de-Ouro-1-2 presented high grain yields, wide adaptability (β1i = 1), high stability (σ2di = 0) and coefficient of determination (R2) greater than 84 (Table 5).

In the evaluation using the method of Wricke (1965)WRICKE, G. Zur berechüng der okovalenz bei sommerweizen und hafer. Zeitschrisft fuer Pflanzezuchtung, v. 52, n.1, p. 127-138, 1965., the most stable genotypes, those that contributed least to the interaction, were MNC01-649F-2-1, MNC02-689F-2-8, MNC02-676F-1 and Pingo-de-Ouro-1-2 and BR17-Gurguéia (Table 5). However, the results were not very descriptive in detecting stable and adapted genotypes. The limitation of this methodology is that it indicates only the contribution of each genotype to the G×E; thus, it cannot show the performance of the genotypes, requiring complementation by other methodologies of adaptability analysis.

According to the methodology of Lin and Binns (1988)LIN, C. S.; BINNS, M. R. A. Superiority measure of cultivar performance for cultivars x location data. Canadian Journal of Plant Science, v. 68, n. 1, p. 193-198, 1988. (modified) (CRUZ; CARNEIRO; REGAZZI, 2014CRUZ, C. D.; CARNEIRO, P. C. S.; REGAZZI, A. J. Modelos biométricos aplicados ao melhoramento genético. 3. ed. Viçosa, MG: UFV, 2014. 668 p. v. 2.), which classifies genotypes for adaptability and phenotypic stability in favorable and unfavorable environments, the most stable genotype is the one that shows the smallest deviation in maximum yield in each environment, i.e., the smallest Pi. Therefore, the lines MNC04-677F-5, MNC02-701F-2 and MNC02-676F-1, and the cultivar BRS-Xiquexique, in addition to presenting the lowest overall Pi, also presented the first positions for the parameters Pi, favorable and unfavorable (Table 6).

Table 6
Estimates of adaptability and phenotypic stability by the method of Lin and Binns (1988)LIN, C. S.; BINNS, M. R. A. Superiority measure of cultivar performance for cultivars x location data. Canadian Journal of Plant Science, v. 68, n. 1, p. 193-198, 1988. (modified), with distribution of Pi (parameter of stability and adaptability) in favorable (Pif) and unfavorable (Pid) environments; and by the method of Annicchiarico (1992) (Wi - confidence index), with distribution in favorable (Wif) and unfavorable (Wid) environments, of 20 cowpea genotypes of semi-prostrate growth habit evaluated in nine experiments conducted in Balsas MA, São Raimundo das Mangabeiras MA, and Primavera do Leste MT, in the 2010, 2011 and 2012 crop seasons

The cultivar BRS-Xiquexique was the most stable, the second most responsive to the favorable environments, and the most adapted to unfavorable environments. The line MNC02-701F-2 was the most responsive to the favorable environments. The most stable and adapted genotypes are the most productive ones.

According to Pereira et al. (2009)PEREIRA, H. S. et al. Adaptabilidade e estabilidade de genótipos de feijoeiro-comum com grãos tipo carioca na Região Central do Brasil. Pesquisa Agropecuária Brasileira, v. 44, n. 1, p. 29-37, 2009., an advantage of the method of Lin and Binns (1988)LIN, C. S.; BINNS, M. R. A. Superiority measure of cultivar performance for cultivars x location data. Canadian Journal of Plant Science, v. 68, n. 1, p. 193-198, 1988. is the immediate identification of more stable genotypes due to the use of the single parameter Pi. Nunes et al. (2014)NUNES, H. F. et al. Grain yield adaptability and stability of blackeyed cowpea genotypes under rainfed agriculture in Brazil. African Journal of Agricultural Research, v. 9, n. 2, p. 255-261, 2014. and Shiringani and Shimelis (2011)SHIRINGANI, R. P.; SHIMELIS, H. A. Yield response and stability among cowpea genotypes at three planting dates and test environment. African Journal of Agricultural Research, v. 6, n. 14, p. 3259-3263, 2011. evaluated cowpea crops and found similar results regarding the parameter Pi, thus confirming that the most adapted and stable genotypes always have the highest yields.

According to the method of Annicchiarico (1992)ANNICCHIARICO, P. Cultivar adaptation and recommendation from alfafa trials in Northern Italy. Journal of Genetics and Plant Breeding, v. 46, n. 3, p. 269-278, 1992., the genotypes BRS-Xiquexique, MNC02-676F-1, MNC02-701F-2, Pingo-de-Ouro-1-2, MNC01-649F-1-3 and MNC01-649F-2-11 were identified with confidence indexes (Wi) greater than 100% (Table 6). The genotypes BRS-Xiquexique, MNC02-701F-2, MNC02-675-4-9, MNC02-677F-5, MNC02-676F-1, MNC01-649F-1-3 and MNC02-677F-2 stood out in favorable environments (Wif); and in unfavorable environments (Wid), 45% of the genotypes surpassed the average of the environments, especially BRS-Xiquexique and Pingo-de-Ouro-1-2.

The Eberhart and Russell (1966)EBERHART, S. A.; RUSSELL, W. A. Stability parameters for comparing varieties. Crop Science, v. 6, n. 1, p. 36-40, 1966. methodology was efficient to indicate genotypes of wide adaptability and high stability, especially the genotypes MNC02-676F-1, MNC01-649F-2-1, MNC02-677F-2 and Pingo-de-Ouro-1-2. This is probably the most appropriate method, since it considers the productivity, adaptability and stability of each cultivar. The genotypes MNC02-676F-1, MNC01-649F-2-1 are among the most stable genotypes, according to methodology of Wricke (1965)WRICKE, G. Zur berechüng der okovalenz bei sommerweizen und hafer. Zeitschrisft fuer Pflanzezuchtung, v. 52, n.1, p. 127-138, 1965.. This result is similar to that found by Mendes de Paula et al. (2014)MENDES DE PAULA, T. O. et al. Relationships between methods of variety adaptability and stability in sugarcane. Genetics and Molecular Research, v. 13, n. 2, p. 4216-4225, 2014., where the methods of Wricke (1965)WRICKE, G. Zur berechüng der okovalenz bei sommerweizen und hafer. Zeitschrisft fuer Pflanzezuchtung, v. 52, n.1, p. 127-138, 1965. and Eberhart and Russell (1966) tended to select the most stable genotypes.

On the other hand, the method based on non-parametric statistics of Lin and Binns (1988)LIN, C. S.; BINNS, M. R. A. Superiority measure of cultivar performance for cultivars x location data. Canadian Journal of Plant Science, v. 68, n. 1, p. 193-198, 1988. (modified), and the method of Annicchiarico (1992)ANNICCHIARICO, P. Cultivar adaptation and recommendation from alfafa trials in Northern Italy. Journal of Genetics and Plant Breeding, v. 46, n. 3, p. 269-278, 1992. indicate the genotypes BRS-Xiquexique and MNC02-701F-2 as those that had the highest yields with high instability and responsiveness to favorable environments. This result is an advantage of this method over methods based on analysis of variance. Conversely, Pereira et al. (2009)PEREIRA, H. S. et al. Adaptabilidade e estabilidade de genótipos de feijoeiro-comum com grãos tipo carioca na Região Central do Brasil. Pesquisa Agropecuária Brasileira, v. 44, n. 1, p. 29-37, 2009. reported that the methods of Lin and Binns (1988) (modified) and Annicchiarico (1992)ANNICCHIARICO, P. Cultivar adaptation and recommendation from alfafa trials in Northern Italy. Journal of Genetics and Plant Breeding, v. 46, n. 3, p. 269-278, 1992. are indicated to be used singly, because they are simple to use and allow the classification of favorable and unfavorable environments, and identification of the most stable and adapted genotypes among the most productive ones. According to the same author, the joint use of methods that presented high correlation is not recommended; in this case, the method of Eberhart and Russell (1966)EBERHART, S. A.; RUSSELL, W. A. Stability parameters for comparing varieties. Crop Science, v. 6, n. 1, p. 36-40, 1966. must be used together with the method of Lin and Binns (1988) (modified) or the method of Annicchiarico (1992)ANNICCHIARICO, P. Cultivar adaptation and recommendation from alfafa trials in Northern Italy. Journal of Genetics and Plant Breeding, v. 46, n. 3, p. 269-278, 1992., since there was no correlation between these methods.

# CONCLUSIONS

1. 1. Considering the results obtained by the joint use of the methods Lin and Binns (1988)LIN, C. S.; BINNS, M. R. A. Superiority measure of cultivar performance for cultivars x location data. Canadian Journal of Plant Science, v. 68, n. 1, p. 193-198, 1988. (modified), Annicchiarico (1992)ANNICCHIARICO, P. Cultivar adaptation and recommendation from alfafa trials in Northern Italy. Journal of Genetics and Plant Breeding, v. 46, n. 3, p. 269-278, 1992. and Eberhart and Russell (1966)EBERHART, S. A.; RUSSELL, W. A. Stability parameters for comparing varieties. Crop Science, v. 6, n. 1, p. 36-40, 1966. is important for analyses in cowpea, since each one has peculiarities that can contribute to the choice of adapted, stable and productive genotypes;

2. The cultivar BRS-Xiquexique and the lines Pingo-de-ouro-1-2, MNC02-676F-1, MNC01-649F-2-1 and MNC02-677F-2 were considered promising. The lines of the commercial subclasses canapu, mulatto, rajado and sempre-verde have potential to be released as commercial cultivars, because they have adaptability and stability for the evaluated environments. The line MNC02-701F-2 presented adaptability and stability for the Cerrado biome, however, it does not have potential as commercial cultivar, since it does not exceed the cultivar BRS-Xiquexique, both belonging to the branco commercial subclass.

• 1

# REFERENCES

• ANNICCHIARICO, P. Cultivar adaptation and recommendation from alfafa trials in Northern Italy. Journal of Genetics and Plant Breeding, v. 46, n. 3, p. 269-278, 1992.
• BARROS, M. A. et al Adaptabilidade e estabilidade produtiva de feijão-caupi de porte semiprostrado. Pesquisa Agropecuária Brasileira, v. 48, n. 4, p. 403-410, 2013.
• BENVINDO, R. N. et al Avaliação de genótipos de feijão-caupi de porte semi-prostrado em cultivo de sequeiro e irrigado. Comunicata Scientiae, v. 1, n. 1, p. 23-28, 2010.
• BERTINI, C. H. C. M.; TEÓFILO, E. M.; DIAS, F. T. C. Divergência genética entre acessos de feijão-caupi do banco de germoplasma da UFC. Revista Ciência Agronômica, v. 40, n. 1, p. 99-105, 2009.
• CARVALHO, L. C. B. et al Evolution of methodology for the study of adaptability and stability in cultivated species. African Journal of Agricultural Research, v. 11, n. 12, p. 990-1000, 2016.
• COCHRAN, W. G. The combination of estimates from different experiments. Biometrics, v. 10, n. 1, p. 101-129, 1954.
• CRUZ, C. D. Genes: a software package for analysis in experimental statistics and quantitative genetics. Acta Scientiarum Agronomy, v. 35, n. 3, p. 271-276, 2013.
• CRUZ, C. D.; CARNEIRO, P. C. S.; REGAZZI, A. J. Modelos biométricos aplicados ao melhoramento genético 3. ed. Viçosa, MG: UFV, 2014. 668 p. v. 2.
• CRUZ, C. D.; REGAZZI, A. J.; CARNEIRO, P. C. S. Modelos biométricos aplicados ao melhoramento genético 4. ed. Viçosa, MG: UFV , 2012. 514 p. v. 1.
• EBERHART, S. A.; RUSSELL, W. A. Stability parameters for comparing varieties. Crop Science, v. 6, n. 1, p. 36-40, 1966.
• FIGUEIREDO, U. J. et al Adaptability and stability of genotypes of sweet sorghum by GGEBiplot and Toler methods. Genetic Molecular Research, v. 14, n. 3, p. 11211-11221, 2015.
• FREIRE FILHO, F. R. et al Feijão-caupi: produção, melhoramento genético, avanços e desafios Brasília, DF: Embrapa Informação Tecnológica, 2011. 81 p.
• FREIRE FILHO, F. R.; LIMA, J. A. A.; RIBEIRO, V. Q. Feijão-caupi: avanços tecnológicos Brasília: Embrapa Informação Tecnológica, 2005. 519 p.
• LIN, C. S.; BINNS, M. R. A. Superiority measure of cultivar performance for cultivars x location data. Canadian Journal of Plant Science, v. 68, n. 1, p. 193-198, 1988.
• MENDES DE PAULA, T. O. et al Relationships between methods of variety adaptability and stability in sugarcane. Genetics and Molecular Research, v. 13, n. 2, p. 4216-4225, 2014.
• NUNES, H. F. et al Grain yield adaptability and stability of blackeyed cowpea genotypes under rainfed agriculture in Brazil. African Journal of Agricultural Research, v. 9, n. 2, p. 255-261, 2014.
• PEREIRA, H. S. et al Adaptabilidade e estabilidade de genótipos de feijoeiro-comum com grãos tipo carioca na Região Central do Brasil. Pesquisa Agropecuária Brasileira, v. 44, n. 1, p. 29-37, 2009.
• PEREIRA, M. A. B. et al Adaptability and productive stability of tomato genotypes in high temperature. Revista Ciência Agronômica, v. 43, n. 2, p. 330-337, 2012.
• PIMENTEL-GOMES, F. Curso de estatística experimental São Paulo: Nobel, 2000. 466 p.
• RESENDE, M. D. V.; DUARTE, J. B. Precisão e controle de qualidade em experimentos de avaliação de cultivares. Pesquisa Agropecuária Tropical, v. 37, n. 3, p. 182-194, 2007.
• ROCHA, M. M. et al Adaptabilidade e estabilidade produtiva de genótipos de feijão-caupi de porte semi-ereto na Região Nordeste do Brasil. Pesquisa Agropecuária Brasileira, v. 42, n. 9, p. 1283-1289, 2007.
• SANTOS, A. et al Adaptability and stability of erect cowpea genotypes via REML/BLUP and GGE Biplot. Bragantia, v. 75, n. 3, p. 299-306, 2016.
• SHIRINGANI, R. P.; SHIMELIS, H. A. Yield response and stability among cowpea genotypes at three planting dates and test environment. African Journal of Agricultural Research, v. 6, n. 14, p. 3259-3263, 2011.
• SILVA, J. A. L.; NEVES, J. A. Produção de feijão-caupi semi-prostrado em cultivos de sequeiro e irrigado. Revista Brasileira de Ciências Agrárias, v. 6, n. 1, p. 29-36, 2011.
• TEIXEIRA, I. T. et al Desempenho agronômico e qualidade de sementes de cultivares de feijão-caupi na região do cerrado. Revista Ciência Agronômica, v. 41, n. 2, p. 300-307, 2010.
• VALADARES, R. N. et al Adaptabilidade e estabilidade fenotípica em genótipos de feijão-caupi (Vigna unguiculata (L.) Walp.) de porte ereto/semi-ereto nas mesorregiões leste e sul maranhense. Agropecuária Científica no Semi-Árido, v. 6, n. 2, p. 21-27, 2010.
• WRICKE, G. Zur berechüng der okovalenz bei sommerweizen und hafer. Zeitschrisft fuer Pflanzezuchtung, v. 52, n.1, p. 127-138, 1965.

# Publication Dates

• Publication in this collection
2017