Agronomic performance of 'BRS' Itaim cowpea beans at different planting densities under no-tillage and conventional systems1 1 Embrapa Macroprograma02: 02.14.01.006.00.10.001

Performance do feijão-caupi BRS Itaim em relação à densidade de plantio e sistemas de semeadura convencional e direta

Milton José Cardoso Edson Alves Bastos Cândido Athayde Sobrinho Francisco de Brito Melo About the authors

ABSTRACT

Cowpea beans play an important role in Brazilian farming, mainly in northern and northeastern regions, where it is widely grown among smallholder farmers. In recent years, commercial farmers have expanded its cultivation, mostly to the Midwest. This study aimed at evaluating the planting density of 'BRS Itaim' black-eyed cowpea beans under conventional (CT) and no-tillage (NT), with 75% mulch in the first year. Two experiments (CT and NT) were conducted at Embrapa Meio-Norte in Teresina - PI (Brazil), during the 2014/2015 harvest. Both experiments were carried out in a randomized block design with four replicates, considering the planting densities (PD) 12, 16, 20, 24, and 28 plants m-2. In both systems, grain yields (GY) and the number of pods per unit area (NPA) responded quadratically to an increase in PD, while a linear decreasing response was observed for the number of pods per unit area. The maximum grain yields (GY) were 1,492 kg ha-1 (23.8 plants m-2) and 1,136 kg ha-1 (23.2 plants m-2) under CT and NT, respectively. The NPA was most correlated with GY, presenting a value of 0.74 (. <0.01). The survival rate of cowpea seedlings was 94% under CT and 88% under NT. This larger reduction under NT might be attributed to a higher incidence of fungi in the soil under this system (e.g. Furasium solani, Fusarium oxysporum, Macrophomina phaseolina, Pythium spp, Sclerotium rolfsii and Rhizoctonia solani).

Key words:
Yield components; Yield grain; Vigna unguiculata (L.) Walp

RESUMO

O feijão-caupi desempenha importante papel na produção agrícola brasileira, especialmente no Norte e Nordeste, onde é amplamente cultivado por agricultores familiares. Nos últimos anos, a cultura, vem se expandindo principalmente no Centro-Oeste por agricultores empresariais. O objetivo do trabalho foi avaliar a densidade de plantio de feijão-caupi BRS Itaim, tipo fradinho, sob sistemas de plantio convencional (SPC) e direto (SPD) com cobertura do solo de primeiro ano em torno de 75%. Foram conduzidos dois ensaios (um em SC e outro em SD) na Embrapa Meio-Norte, em Teresina, PI, safra 2014/2015. Nos dois ensaios utilizou-se o delineamento experimental de blocos casualizados com quatro repetições, considerando-se as densidades de plantio (DP) de 12; 16; 20; 24 e 28 plantas m-2. Em ambos os sistemas, as produtividades de grãos (PG) e os componentes de rendimento número de vagens por área (NVA) responderam quadraticamente ao aumento da DP, enquanto a resposta linear decrescente foi observada para o número de vagens por planta. As PG máximas foram de 1.492 kg ha-1 (23,8 plantas m-2) e 1.136 kg ha-1 (23,2 plantas m-2) nos sistemas de SC e SD, respectivamente. O NVA foi o mais correlacionado com a PG com valor 0,74 (. <0,01). A sobrevivência de plantas de feijão-caupi foi de 94% no sistema de SC e de 88% no sistema de SD, sendo a maior redução observada no sistema de semeadura direta atribuída à maior incidência dos fungos de solo (Furasium solani, Fusarium oxysporum, Macrophomina phaseolina, Pythium spp, Sclerotium rolfsii e Rhizoctonia solani).

Palavras-chave:
Componentes de produção; Produtividade de grãos; Vigna unguiculata (L.) Walp

INTRODUCTION

One of the major problems in cowpea cultivation regions, mainly in Northeastern and Northern Brazil, is related to rainfall unevenness together with other factors such as sandy soils, high temperatures, and inadequate management measures just as planting density, which contributes to a low yielding of grains, about 0.22 t ha-1 (CONAB, 2016). This values are much lower than those beans grown under a high-tech production system (BRACHTVOGEL ., 2009BRACHTVOGEL, E. L. et al. Densidades populacionais de milho em arranjos espaciais convencional e equidistante entre plantas. Ciência Rural, v. 39, n. 8, p. 2334-2339, 2009.; CARDOSO; RIBEIRO, 2006CARDOSO, M. J.; RIBEIRO, V. Q. Desempenho agronômico do feijão caupi, cv. Rouxinol, em função de espaçamentos entre linhas e densidades de plantas sob regime de sequeiro. Revista Ciência Agronômica, v. 37, n. 1, p. 102-105, 2006.; MAKOI; CHIMPHANGO; DAKORA, 2009MAKOI, J. H. J. R.; CHIMPHANGO, S. B. M.; DAKORA, F. D. Effect of legume plant density and mixed culture on symbiotic N 2 fixation in five cowpea [Vigna unguiculata (L.) Walp] genotypes in South Africa. Symbiosis, v. 48, p. 57-67, 2009. ; MATOS FILHO 2009MATOS FILHO, C. H. A. et al. Potencial produtivo de progênies de feijão-caupi com arquitetura ereta de planta. Ciência Rural, v. 39, n. 2, p. 348 -354, 2009.; MENDES et al., 2007; NJOKU; MUONEKE, 2008NJOKU, D. N.; MUONEKE, C. O. Effect of cowpea planting density on growth, yield and productivity of component crops in cowpea/cassava intercropping system. Journal of Tropical Agriculture, Food Environment and Extension, v. 7, n. 2, p. 106-113, 2008.; OLIVEIRA FILHO ., 2016OLIVEIRA FILHO, A. F. et al. Eficiência agronômica e biológica nos consórcios da mamoneira com feijão-caupi ou milho. Revista Ciência Agrônomica, v. 47, n. 4, p. 729-736, 2016. ; OROKA; OMEREGIE, 2007OROKA, F. O.; OMEREGIE, A. U. Competition in a rice: cowpea intercrop as affected by nitrogen fertilizer and plant population. Scientia Agricola, v. 64, n. 6, p. 621-629, 2007. ).

Cowpea beans have been intensely researched in recent years, which have been leading to improvements in both crop yield and its profitability. This scrutiny has aroused the interest of medium and large farmers (FREIRE FILHO , 2011FREIRE FILHO, F. R. et al. Feijão-caupi no Brasil: produção, melhoramento genético, avanços e desafios. Teresina: Embrapa Meio-Norte , 2011, 84 p.; OLIVEIRA FILHO ., 2016OLIVEIRA FILHO, A. F. et al. Eficiência agronômica e biológica nos consórcios da mamoneira com feijão-caupi ou milho. Revista Ciência Agrônomica, v. 47, n. 4, p. 729-736, 2016. ). Among the agricultural practices being studied, planting density (PD) and cropping system (CS), both conventional (CT) and no-tillage (NT), have stood out. The first refers to plant spatial arrangements and is the most important to optimize crop yield since influences the leaf area index, foliar insertion angle, and the interception of incident light by plants, particularly in lower canopy layers. Therefore, PD directly affects solar radiation interception, being one of the most defining factors of GY. While studying BRS Guariba, Bezerra . (2012)BEZERRA, A. A. de C. et al. Comportamento morfoagronômico de feijão caupi, cv. BRS Guariba, sob diferentes densidades de plantas. Revista de Ciências Agrárias, v. 55, n. 3, p. 184-189, 2012. observed a 63.8% reduction in the number of pods per plant (NPP), and 67.6% decrease in grain yield per plant (GYP), by raising PD in 100 and 500 thousand plants ha-1, respectively. For BRS Novaera, Bezerra et al. (2014) reported declines of 66.5% and 59.53% in NPP and GY, respectively. Naim, Jabereldar, and Mohamed (2011)NAIM, A. M.; JABERELDAR, A. A.; MOHAMED, E. A. Effect of seed rate and cultivar on yield and yields components of cowpea (Vigna unguicula (L.) Walp) in Kordofan of Sudan. International Journal of Currente Research, v. 2, n. 1, p. 142-147, 2011., while investigating the PDs of 6, 12, 18, and 24 kg ha-1, observed an increase in the number of grains per area, as well as reductions in NPP, 100-grain weight, GYP, and harvest index.

NT might be considered promising to the detriment of CT when growing cowpeas by the soil mulching effect that maintain moisture and contribute to weed control. This system may also be taken as an alternative to reduce water deficit risks in crops and improve water use efficiency. Since soil temperatures are very high in Northeastern Brazil, a further advantage of an NT relies on the reduction of soil temperature by mulching, as a protection against the sunrays, what also would minimize the drastic climatic effects unfavorable to a crop development (SIMIDU ., 2010SIMIDU, H. M. et al. Efeito do adubo verde e época de semeadura sobre a produtividade do feijão, em plantio direto em região de cerrado. Acta Scientiarum Agronomy, v. 32, n. 2, p. 309-315, 2010.).

Fontes, Oliveira and Rocha (2013)FONTES, J. R. A.; OLIVEIRA, I. J. de; ROCHA, R. N. C. da. Produção de feijão-caupi em diferentes sistemas de manejo do solo no amazonas. In: CONGRESSO NACIONAL DE FEIJÃO CAUPI, 3., 2013, Recife. Resumos expandidos... Recife: IPA: Embrapa, 2013. have already tested the feasibility of growing cowpeas under NT; they proved that this system showed compatibility with the regional-recommended CT in terms of both PD and GY.

Furthermore, in a study of irrigated NT, Locatelli . (2014)LOCATELLI, V. da E. R. et al. Componentes de produção, produtividade e deficiência da irrigação do feijão-caupi no cerrado de Roraima. Revista Brasileira de Engenharia Ambiental, v. 18, n. 6, p. 574-580, 2014. pointed the lack of influence on BRS Pajeú yield components; the same authors reported that BRS Guariba and BRS Novaera obtained maximum GYs of 1.28 and 1.51 t ha-1 using water depths of 74.3 and 94.0% ET0, respectively.

The objective of this study was to evaluate the planting density for 'BRS Itaim' cowpea beans under conventional tillage and no-till with 75% soil mulching in the first year.

MATERIAL AND METHODS

The study was conducted in a Yellow Argisol (JACOMINE ., 2013JACOMINE, P. K. T. et al. Sistema brasileiro de classificação de solos. 3. ed. rev. ampl. Brasília, DF: Embrapa, 2013. 353 p.; MELO, ANDRADE JÚNIOR; PESSOA, 2014MELO, F. de B.; ANDRADE JÚNIOR, A. S.; PESSOA, B. L. de O. Levantamento, zoneamento e mapeamento pedológico detalhado da área experimental da Embrapa Meio-Norte em Teresina, PI. Teresina : Embrapa Meio-Norte, 2014. 47 p. (Embrapa Meio Norte. Documentos, 231).) in a rainfed area during the 2014/2015 harvest (March to May of 2015). This area is located at a property belonging to the Embrapa Meio-Norte, in Teresina microregion (PI), Brazil. The local geographical coordinates are 05º02'09.9" S, 42º47'544" W, and 69.0-m altitude. Soil chemical analysis of samples collected at 20 cm depth was carried out at the Laboratory of Soil Fertility (Embrapa Meio-Norte). The analysis showed the following results: pH (H2O 1: 2.5) = 5.4; phosphorus (mg dm-3) = 4.0; potassium (cmolc dm-3) = 0.14; calcium (cmolc dm-3) = 3.1; magnesium (cmolc dm-3) = 1.4; aluminum (cmolc dm-3) = 0.1, and organic matter (g kg-1) = 30.1.

Two experiments with cowpea beans (BRS Itaim cultivar, erect black-eyed) were installed side by side in a randomized block design with four replicates. One experiment was carried out under CT and the other under NT with 75% soil mulching in the first year (Figure 1). Treatments consisted of five planting densities (12, 16, 20, 24, and 28 plants m-2).

Figure 1
BRS Itaim cowpea beans under conventional tillage (left) and under no-tillage (right). Teresina, PI. 2014/2015 harvest season. (Photo by Milton José Cardoso)

The plots were 5-m long and consisted of four 0.5-m rows. The useful area was composed of the two central rows. During sowing, on March 25, 2015, surplus amounts of seeds were sown in the rows and, by occasion of thinning out, the right amount of plants was maintained according to the density to be tested. Basal dressing consisted of 60 kg P205 ha-1 (simple superphosphate) and 50 kg K20 ha-1 (potassium chloride), and N topdressing of 20 kg ha-1 (simple superphosphate), being applied on the fifteenth day of sowing. Figure 2 shows the monthly rainfall (mm) and means of air temperature recorded during the evaluated crop cycle.

Figure 2
Monthly rainfall (mm) and means of air temperature during the evaluated crop cycle (March-May 2015) of 'BRS Itaim' cowpea beans. Teresina, Piauí. Data source: an agrometeorological station located 300 m away from the experimental area

The agronomic traits assessed were pod length (PL), number of pods per plant (NPP), number of pods per unit area (NPA), 100-grain weight (100-GW; in grams), seedling survival (ratio between the initial and final plant stand), and grain weight (GW; in kg per useful area unit), and weight corrected to 13% moisture (CGW). The latter was estimated by the following equation: CGW = [(100-Mi) x GY)/ (100-Mf)]); wherein, CGW is the corrected grain weight, Mi is the grain moisture by a moisture meter (Gehaka, G600i), Mf is the grain moisture to be corrected (13%). The first four trains were analyzed for ten pods chosen at random from the useful area of each treatment. Grain yield (GYHA; kg ha-1) was determined by the equation: GYHA = (10,000 m2 x CGW kg) / (useful m2). The incidence of diseases, characterized as root and stem rot, was inspected by counting the number of symptomatic plants in each plot, thus confirming etiology at the Laboratory of Plant Pathology, Embrapa Meio-Norte, Piauí State (Brazil).

First- and second-degree regressions on variance analysis data were performed for plant densities following the method described by Pimentel-Gomes (2009)PIMENTEL-GOMES, F. Curso de estatística experimental. 15. ed. Piracicaba: ESALQ, 2009. 451 p. (Biblioteca de Ciências Agrárias "Luiz de Queiroz", 15) and Zimmermann (2014)ZIMMERMANN, F. J. P. Estatística aplicada à pesquisa agrícola. 2. ed. revisada e ampliada. Brasília, DF: Embrapa ; Santo Antônio de Goiás: Embrapa Arroz e Feijão, 2014. 582 p.. Considering the t-test, the best model was selected by the significance of each parameter, accepting a significance level up to 15% probability (CONAGIN, JORGE, 1982CONAGIN, A.; JORGE, J. P. N. de. Delineamento (1/5)(5x5x5) em blocos. Bragantia, v. 41, n. 16, p. 155-168. 1982.).

The method developed by Alvarez V. and Alvarez (2003)ALVAREZ V., V. H. ; ALVAREZ, G. A. M. Apresentação de equações de regressão e suas interpretações. Boletim Informativo da Sociedade Brasileira de Ciência do Solo, v. 28, n. 3, p. 28-32, 2003. was also followed, in which an equation is significant regardless the significance of coefficients. Nonetheless, the model significance must be explicit in the equation (for regression coefficient), besides showing an R2 significance. All statistical analyses were performed using SAS software (SAS INSTITUTE, 2015SAS INSTITUTE. SAS/STAT(r) 14.1 User's Guide. Cary, 2015. Available at: <http://support.sas.com/documentation/cdl/en/statug/68162/PDF/default/statug.pdf>. Accessed on: Jan. 26, 2016.
http://support.sas.com/documentation/cdl...
).

RESULTS AND DISCUSSION

The variance analysis showed significant effects from planting densities on the number of pods per plant, number of pods per area, and grain yield (Table 1). The same trend was registered for the cropping system for the same traits (Table 2).

Table 1
Variance analysis for pod length (PL); number of grains per pod (NGP), grain yield per hectare (GYHA), 100-grain weight (100-GW), number of pods per plant (NPP), number of pods per area (NPA), and seedling survival (SUR) in ‘BRS Itaim' cowpea beans. Teresina, PI, 2014/2015 harvest season
Table 2
Means of pod length (PL), number of grains per pod (NGP), 100-grain weight (100-GW), number of pods per plant (NPP), number of pods per square meter per area (NPA), seedling survival (SUR), and grain yield (GYHA) in ‘BRS Itaim' cowpea beans under conventional tillage (CT) and no-tillage (NT). Teresina, PI, 2014/2015 harvest season

By analyzing the interaction between CS x PD, we noticed an effect (P<0.01) on the yield components NPP, NPA, and GY. While NPP showed a linear decreasing response, NPA presented a quadratic response when increasing PD (Figure 3). We observed that by increasing NPA in one, there was a decrease of 0.181 and 0.073 pods per plant in CT and NT, respectively. It was a quadratic response to PD increase, which reached a maximum of 94.72 pods/ m-2 (CT with 22.27 plants/ m-2) and 64.68 pods/ m-2 (NT with 25.4 plants/ m-2). (Figure 3).

Figure 3
Number of pods.m-2 and number of pods.plant-1 of 'BRS Itaim' cowpea beans under conventional tillage (CT) and no-tillage (NT). Teresina, PI, 2014/2015 harvest season

**and *: significant at 1% and 5% level by the F-test, respectively

Bezerra . (2009)BEZERRA, A. A. de C. et al. Características de dossel e de rendimento em feijão-caupi ereto em diferentes densidades populacionais. Pesquisa Agropecuária Brasileira, v. 44, n. 10, p. 1239- 1245, 2009., Cardoso; Ribeiro and Bastos (2015)CARDOSO, M. J.; RIBEIRO, V. Q.; BASTOS, E. A. Densidades de plantas de feijão-caupi de porte semi-prostrado sob irrigação. Teresina: Embrapa Meio-Norte, 2015. 21 p. (Boletim de Pesquisa e Desenvolvimento. Embrapa Meio-Norte, 110), and Naim; Jabereldar (2010)NAIM, A. M.; JABERELDAR, A. A. Effect of plant density and cultivar on growth and yield of cowpea (Vigna unguiculata (L.)Walp.). Australian Journal of Basic and Applied Sciences, v. 4, n. 8, p. 3148-3153, 2010. also observed similar behavior for the same traits when increasing NPA. One of the reasons for these scenarios might have been caused by intraspecific competition, probably due to a lower blossoming, which could have been aggravated by water stress during flourishing and pod filling stages. Similar results were observed by Likewise, Bezerra . (2008)BEZERRA, A. A. de C. et al. Morfologia e produção de grãos em linhagens modernas de feijão-caupi submetidas a diferentes densidades populacionais. Revista de Biologia e Ciências da Terra, v. 8, n. 1, p. 85-93, 2008., Cardoso, Ribeiro and Bastos (2015), Lemma, Worku and Woldemichael (2009)LEMMA, G.; WORKU, W.; WOLDEMICHAEL, A. Moisture and planting density interactions affect productivity in cowpea (Vigna unguiculata). Journal of Agronomy, v. 8, n. 4, p. 117-123, 2009. , Naim and Jabereldar (2010)NAIM, A. M.; JABERELDAR, A. A.; MOHAMED, E. A. Effect of seed rate and cultivar on yield and yields components of cowpea (Vigna unguicula (L.) Walp) in Kordofan of Sudan. International Journal of Currente Research, v. 2, n. 1, p. 142-147, 2011., and Távora, Nogueira and Pinho (2001)TÁVORA, F. J. A. F.; NOGUEIRA, S. L.; PINHO, J. L. N. de. Arranjo e população de plantas em cultivares de feijão-de-corda com diferentes características de copa. Revista Ciência Agronômica, v. 32, p. 69-77, 2001..

Quadratic response of GY by increasing PD (Figure 4) was observed, with maximum GY values of 1,492 kg ha-1 (23.8 plants m-2) and 1,136 kg ha-1 (23.2 plants m-2) under CT and NT, respectively. In addition, the same trend was observed by Cardoso and Ribeiro (2006)CARDOSO, M. J.; RIBEIRO, V. Q. Desempenho agronômico do feijão caupi, cv. Rouxinol, em função de espaçamentos entre linhas e densidades de plantas sob regime de sequeiro. Revista Ciência Agronômica, v. 37, n. 1, p. 102-105, 2006., Naim and Jabereldar (2010)NAIM, A. M.; JABERELDAR, A. A. Effect of plant density and cultivar on growth and yield of cowpea (Vigna unguiculata (L.)Walp.). Australian Journal of Basic and Applied Sciences, v. 4, n. 8, p. 3148-3153, 2010., Bezerra . (2014)BEZERRA, A. A. de C. et al. . Morfologia e produção de feijão-caupi, culvivar BRS Novaera, em função da densidade de plantas. Revista Caatinga, v. 27, n. 4, p. 135-141, 2014., and Cardoso, Ribeiro and Bastos (2015). Distinctly, Jallow and Ferguson (1985)JALLOW, A. T.; FERGUSON, T. U. Effects on planting density and cultivar of seed yield of cowpeas (Vigna unguiculata (L.) Walp.) in Trinidad. Tropical Agriculture, v. 62, n. 2, p. 121-124, 1985. observed linear effects by varying PD from 4 to 25 plants m-2 in eight cultivars of cowpea beans.

Figure 4
Grain yield of 'BRS Itaim' cowpea beans under conventional tillage (CT) and no-tillage (NT). Teresina, PI, 2014/2015 harvest season

**and *: significant at 1% and 5% level by the F-test, respectively

Table 3 highlights that NPA was the yield component mostly correlated (P<0.01) with grain yield, presenting an average of 0.74.

Table 3
Pearson's Correlation for grain yield per hectare (GYHA), pod length (PL), number of grains per pod (NGP), 100-grain weight (100-GW), number of pods per plant (NPP), number of pods per area (NPA), and seedling survival (SUR) of 'BRS Itaim' cowpea beans under conventional tillage (CT) and no-tillage (NT).Teresina, PI, 2014/2015 harvest season

Additionally, a higher incidence of soil fungi was observed in plants under NT when compared to CT (Fusarium solani, Fusarium oxysporum, Macrophomina phaseolina, Pythium spp, Sclerotium rolfsii and Rhizoctonia solani), affecting the plant survival, which was 94% under CT and 88% under NT.

CONCLUSIONS

  1. Under a no-tillage system with first year mulching, increasing plant densities cause a reduction in grain yield of 'BRS Itaim' cowpea beans as well as it favors soil fungi attack compared to a conventional tillage system;

  2. Grain yield response to planting density is quadratic, reaching maximum values of 1,492 kg ha-1 (23.8 plants m-2) and 1,136 kg ha-1 (23.2 plants m-2) under conventional and no-tillage systems, respectively. The yield component mostly correlated with grain yield was the number of pods per area, with a significant value of 0.74;

  3. With the increase of planting density, the yield components number of pod per plant and number of pods per area are majorly affected in a no-tillage if compared to a conventional tillage system;

  4. Under both conventional and no-tillage systems, the number of pods per area is the component mostly correlated with grain yield.

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    Embrapa Macroprograma02: 02.14.01.006.00.10.001

REFERENCES

  • ALVAREZ V., V. H. ; ALVAREZ, G. A. M. Apresentação de equações de regressão e suas interpretações. Boletim Informativo da Sociedade Brasileira de Ciência do Solo, v. 28, n. 3, p. 28-32, 2003.
  • BEZERRA, A. A. de C. et al Características de dossel e de rendimento em feijão-caupi ereto em diferentes densidades populacionais. Pesquisa Agropecuária Brasileira, v. 44, n. 10, p. 1239- 1245, 2009.
  • BEZERRA, A. A. de C. et al Comportamento morfoagronômico de feijão caupi, cv. BRS Guariba, sob diferentes densidades de plantas. Revista de Ciências Agrárias, v. 55, n. 3, p. 184-189, 2012.
  • BEZERRA, A. A. de C. et al . Morfologia e produção de feijão-caupi, culvivar BRS Novaera, em função da densidade de plantas. Revista Caatinga, v. 27, n. 4, p. 135-141, 2014.
  • BEZERRA, A. A. de C. et al Morfologia e produção de grãos em linhagens modernas de feijão-caupi submetidas a diferentes densidades populacionais. Revista de Biologia e Ciências da Terra, v. 8, n. 1, p. 85-93, 2008.
  • BRACHTVOGEL, E. L. et al Densidades populacionais de milho em arranjos espaciais convencional e equidistante entre plantas. Ciência Rural, v. 39, n. 8, p. 2334-2339, 2009.
  • CARDOSO, M. J.; RIBEIRO, V. Q. Desempenho agronômico do feijão caupi, cv. Rouxinol, em função de espaçamentos entre linhas e densidades de plantas sob regime de sequeiro. Revista Ciência Agronômica, v. 37, n. 1, p. 102-105, 2006.
  • CARDOSO, M. J.; RIBEIRO, V. Q.; BASTOS, E. A. Densidades de plantas de feijão-caupi de porte semi-prostrado sob irrigação Teresina: Embrapa Meio-Norte, 2015. 21 p. (Boletim de Pesquisa e Desenvolvimento. Embrapa Meio-Norte, 110)
  • COMPANHIA NACIONAL DE ABASTECIMENTO. Acompanhamento da safra brasileira: grãos: safra 2015/2016: oitavo levantamento. Brasília, v. 8, p. 1-178, maio 2016. Available at: <http://www.conab.gov.br/OlalaCMS/uploads/arquivos/16_07_29_15_12_51_boletim_graos_julho_2016.pdf> Accessed on: Aug. 08, 2016.
    » http://www.conab.gov.br/OlalaCMS/uploads/arquivos/16_07_29_15_12_51_boletim_graos_julho_2016.pdf
  • CONAGIN, A.; JORGE, J. P. N. de. Delineamento (1/5)(5x5x5) em blocos. Bragantia, v. 41, n. 16, p. 155-168. 1982.
  • FONTES, J. R. A.; OLIVEIRA, I. J. de; ROCHA, R. N. C. da. Produção de feijão-caupi em diferentes sistemas de manejo do solo no amazonas. In: CONGRESSO NACIONAL DE FEIJÃO CAUPI, 3., 2013, Recife. Resumos expandidos... Recife: IPA: Embrapa, 2013.
  • FREIRE FILHO, F. R. et al Feijão-caupi no Brasil: produção, melhoramento genético, avanços e desafios. Teresina: Embrapa Meio-Norte , 2011, 84 p.
  • JACOMINE, P. K. T. et al Sistema brasileiro de classificação de solos 3. ed. rev. ampl. Brasília, DF: Embrapa, 2013. 353 p.
  • JALLOW, A. T.; FERGUSON, T. U. Effects on planting density and cultivar of seed yield of cowpeas (Vigna unguiculata (L.) Walp.) in Trinidad. Tropical Agriculture, v. 62, n. 2, p. 121-124, 1985.
  • LEMMA, G.; WORKU, W.; WOLDEMICHAEL, A. Moisture and planting density interactions affect productivity in cowpea (Vigna unguiculata). Journal of Agronomy, v. 8, n. 4, p. 117-123, 2009.
  • LOCATELLI, V. da E. R. et al Componentes de produção, produtividade e deficiência da irrigação do feijão-caupi no cerrado de Roraima. Revista Brasileira de Engenharia Ambiental, v. 18, n. 6, p. 574-580, 2014.
  • MAKOI, J. H. J. R.; CHIMPHANGO, S. B. M.; DAKORA, F. D. Effect of legume plant density and mixed culture on symbiotic N 2 fixation in five cowpea [Vigna unguiculata (L.) Walp] genotypes in South Africa. Symbiosis, v. 48, p. 57-67, 2009.
  • MATOS FILHO, C. H. A. et al Potencial produtivo de progênies de feijão-caupi com arquitetura ereta de planta. Ciência Rural, v. 39, n. 2, p. 348 -354, 2009.
  • MELO, F. de B.; ANDRADE JÚNIOR, A. S.; PESSOA, B. L. de O. Levantamento, zoneamento e mapeamento pedológico detalhado da área experimental da Embrapa Meio-Norte em Teresina, PI. Teresina : Embrapa Meio-Norte, 2014. 47 p. (Embrapa Meio Norte. Documentos, 231).
  • MENDES, R. M. S. et al. Alterações na relação fonte-dreno em feijão-de-corda submetido a diferentes densidades de plantas. Revista Ciência Agronômica, v. 36, n. 1, p. 82-90, 2005.
  • NAIM, A. M.; JABERELDAR, A. A. Effect of plant density and cultivar on growth and yield of cowpea (Vigna unguiculata (L.)Walp.). Australian Journal of Basic and Applied Sciences, v. 4, n. 8, p. 3148-3153, 2010.
  • NAIM, A. M.; JABERELDAR, A. A.; MOHAMED, E. A. Effect of seed rate and cultivar on yield and yields components of cowpea (Vigna unguicula (L.) Walp) in Kordofan of Sudan. International Journal of Currente Research, v. 2, n. 1, p. 142-147, 2011.
  • NJOKU, D. N.; MUONEKE, C. O. Effect of cowpea planting density on growth, yield and productivity of component crops in cowpea/cassava intercropping system. Journal of Tropical Agriculture, Food Environment and Extension, v. 7, n. 2, p. 106-113, 2008.
  • OLIVEIRA FILHO, A. F. et al Eficiência agronômica e biológica nos consórcios da mamoneira com feijão-caupi ou milho. Revista Ciência Agrônomica, v. 47, n. 4, p. 729-736, 2016.
  • OROKA, F. O.; OMEREGIE, A. U. Competition in a rice: cowpea intercrop as affected by nitrogen fertilizer and plant population. Scientia Agricola, v. 64, n. 6, p. 621-629, 2007.
  • PIMENTEL-GOMES, F. Curso de estatística experimental 15. ed. Piracicaba: ESALQ, 2009. 451 p. (Biblioteca de Ciências Agrárias "Luiz de Queiroz", 15)
  • SAS INSTITUTE. SAS/STAT(r) 14.1 User's Guide Cary, 2015. Available at: <http://support.sas.com/documentation/cdl/en/statug/68162/PDF/default/statug.pdf>. Accessed on: Jan. 26, 2016.
    » http://support.sas.com/documentation/cdl/en/statug/68162/PDF/default/statug.pdf
  • SIMIDU, H. M. et al Efeito do adubo verde e época de semeadura sobre a produtividade do feijão, em plantio direto em região de cerrado. Acta Scientiarum Agronomy, v. 32, n. 2, p. 309-315, 2010.
  • TÁVORA, F. J. A. F.; NOGUEIRA, S. L.; PINHO, J. L. N. de. Arranjo e população de plantas em cultivares de feijão-de-corda com diferentes características de copa. Revista Ciência Agronômica, v. 32, p. 69-77, 2001.
  • ZIMMERMANN, F. J. P. Estatística aplicada à pesquisa agrícola 2. ed. revisada e ampliada. Brasília, DF: Embrapa ; Santo Antônio de Goiás: Embrapa Arroz e Feijão, 2014. 582 p.

Publication Dates

  • Publication in this collection
    2017

History

  • Received
    23 Aug 2016
  • Accepted
    02 Feb 2017
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