Agronomic performance of cowpea genotypes in southwestern Brazilian Amazon

Abstract

The objective of this work was to evaluate the agronomic performance of cowpea (Vigna unguiculata) genotypes over three crop years, in the ecosystem of Rio Branco, in the state of Acre, Brazil. The experiments were carried out in the 2016, 2017, and 2018 crop seasons, in a randomized complete block design, with four replicates. Eight agronomic traits were evaluated in 14 cowpea genotypes, which included: 12 lines (BDO 1-5-11, BDO 1-5-15, BDO 1-5-19, BDO 1-5-24, PDO 1-5-26, PDO 1-5-4, PDO 1-5-5, PDO 1-5-7, PDO 1-5-8, PDO 1-5-10, PDO 1-5-11, and PDO 1-5-14) and two cultivars (BRS Tumucumaque and BRS Imponente). A significant difference was observed in the genotype x crop year interaction, for most traits. Although there was no statistical difference between genotypes in the studied crop years, dry seed productivity was higher than the national average. All cowpea lines and cultivars from the genetic breeding program show equivalent and favorable agronomic performances in the environmental conditions of Rio Branco. Therefore, these genotypes can be selected for incorporation into the production system of Rio Branco.

Characterization of cowpea cultivars for grain size, color, and biofortification

“…This result confirms the extra-large grain size of the cultivar BRS-Imponente (ROCHA; DAMASCENO-SILVA; MENEZES-JÚNIOR, 2017). However, Marinho et al (2021) found grain sizes ranging from 31.50 to 35.50 g 100 grains -1 for the cultivar BRS-Imponente, smaller than the means found in the present study.…”

“…The comparison between the overall mean grain size of cultivars of the white class and the overall mean of cultivars of the colors + black class showed superiority for the white class, which differed from the colors + black classes and the overall mean of the cultivars. This result confirms those of the Freire Filho (2011), who reported occurrence of larger grain sizes for cultivars of the white class; in addition, Marinho et al (2021) reported larger grain sizes and rough texture for the cultivars BR-3-Tracuateua and BRS-Imponente. The market demand for cowpea cultivars with larger grains is high in Brazil; thus, cultivars with larger grains have higher prices.…”

“…Grain size ranged from 13.55 to 37.88 g 100 grains -1 , with an overall mean of 21.50 g 100 grains -1 . This range is greater than that found by Marinho et al (2021), who evaluated 14 cowpea genotypes in the state of Acre, Brazil, from 2016 to 2018 and found a range of 19.94 to 34.03 g 100 grains -1 ; however, the mean was similar (21.88 g 100 grains -1 ). The largest grain sizes were found for cultivars in group A, namely, BR-3-Tracuateua and BRS-Imponente, with 29.31 and 37.88 g 100 grains -1 , respectively.…”

“…Grain size is little affected by environmental factors and most of the observed variation is due to genetic causes, which facilitates the selection of superior genotypes for this character (MARINHO et al, 2021). However, grain size is more affected by the environment than nutritional characters.…”

“…Thus, another factor that can explain the differences in grain size found for BRS-Imponente is the genotype × environment interaction, which can affect the phenotype, increasing or decreasing the grain size. Moreover, Marinho et al (2021) conducted a study in Acre, North region of Brazil, whereas the present work was conducted in Piauí, Northeast region of Brazil; these Brazilian regions have very different soil and climate conditions, which can significantly affect the phenotypes of the cultivars, including grain size.…”