Valdenir Queiroz Ribeiro

O feijão-caupi [Vigna unguiculata (L.) Walp.] é uma cultura alimentar que faz parte da dieta do paraense desde meados do século XVIII, entretanto, ainda é muito carente de inovações tecnológicas em, praticamente, todas as etapas de sua cadeia produtivo-comercial. O presente trabalho teve como objetivo avaliar o desempenho de 12 linhagens e 2 cultivares de feijão-caupi do tipo cores, visando identificar genótipos que possam ser recomendados para cultivo na região Bragantina, no estado do Pará. O delineamento experimental utilizado foi o de blocos casualizados com 14 tratamentos e 4 repetições. Os resultados de produtividade foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey, ao nível de 5% de probabilidade. podendo ser recomendados para cultivo nas condições edafoclimáticas da região de Bragança, no estado do Pará. Os 14 genótipos de feijão-caupi avaliados nos anos de 2016, 2017 e 2018 apresentaram potencial de produtividade média de grãos secos de feijão-caupi, superior à média do estadual de 747 kg ha1. Então podem ser cultivados na região bragantina no estado do Pará.

PERFORMANCE AGROINDUSTRIAL DE CANA-DE-AÇÚCAR EM DIFERENTES REGIMES HÍDRICOS     EDUARDO MAGNO PEREIRA DA SILVA¹; ADERSON SOARES DE ANDRADE JÚNIOR²; EDSON ALVES BASTOS² E VALDENIR QUEIROZ RIBEIRO^{2   1}Instituto Federal de Educação, Ciência e Tecnologia do Piauí - Campus Uruçuí Rodovia PI 247, S/N - Portal dos Cerrados, CEP: 64860-000, Uruçuí, Piauí, Brasil, e-mail: eduardo.silva@ifpi.edu.br ²Embrapa Meio‑Norte, Avenida Duque de Caxias, n° 5.650, Bairro Buenos Aires, CEP64006‑220, Teresina, Piauí, Brasil, e-mail: aderson.andrade@embrapa.br, edson.bastos@embrapa.br, valdenir.queiroz@embrapa.br 1 RESUMO   O objetivo desta pesquisa foi avaliar a performance agroindustrial de cana-de-açúcar (planta) em resposta a diferentes regimes hídricos aplicados por gotejamento subsuperficial. O experimento foi realizado em um argissolo vermelho amarelo distrófico, na Embrapa Meio-Norte, em Teresina, Piauí, durante o período de outubro de 2015 a setembro de 2016. Modelou-se o experimento em delineamento experimental de blocos casualizados em parcelas subdivididas, com quatro repetições. As parcelas foram constituídas por quatro regimes hídricos (irrigação mais precipitação pluviométrica) baseados em frações da evapotranspiração de cultura (50% ETc = 1.374,3; 80% ETc = 1.534,2; 110% ETc = 1.712,0 e 150% ETc = 1.905,8 mm) e as subparcelas por dez variedades de cana-de-açúcar (RBUFRPE01, RBUFRPE02, RBUFRPE03, RBUFV01, RB036066, RB987935, RB935744, RB943538, RB92579 e RB867515). As características tecnológicas de qualidade do caldo da cana e rendimentos de açúcar e álcool foram alterados pelos regimes hídricos e variedades. Os maiores teores de Brix (22,5%), Fibras (13,3%), Polcaldo (17,5%) e Polcana (13,9%) foram obtidos com as variedades RB867515, RB935744, RB943538 e RB935744, respectivamente. Os rendimentos de açúcar (32,2 Mg ha^-1) e álcool (23 m³ ha^-1) foram alcançados com a variedade RB935744 e reposição hídrica próxima a 110% da ETc. Palavras-chave: Saccharum officinarum, eficiência da água, manejo da irrigação. SILVA, E. M. P.; ANDRADE JÚNIOR, A. S.; BASTOS, E. A.; RIBEIRO, V. Q. AGRO-INDUSTRIAL PERFORMANCE OF SUGARCANE IN DIFFERENT WATER REGIMES   The objective of this research was to evaluate the agro-industrial performance of sugarcane varieties (cane plant) in response to different water regimes applied by subsurface drip irrigation. The experiment was carried out in a dystrophic yellow red acrisol at Embrapa Middle North, Teresina, Piauí State, Brazil, from October 2015 to September 2016. The experiment was designed in a randomized block design in subdivided plots, with four replications. The plots consisted of four water regimes (irrigation plus rainfall) based on crop evapotranspiration fractions (50% ETc = 1,374.3 mm, 80% ETc = 1,534.2 mm, 110% ETc = 1,712.0 mm and 150% ETc = 1,905.8 mm) and the subplots per ten varieties of sugarcane (RBUFRPE01, RBUFRPE02, RBUFRPE03, RBUFV01, RB036066, RB987935, RB935744, RB943538, RB92579 and RB867515). The technological quality characteristics of sugarcane juice and yields of sugar and alcohol were affected by water regimes and varieties. The highest contents of Brix (22.5%), Fibers (13.3%), Pol-juice (17.5%) and Pol-stalk (13.9%) were obtained with varieties RB867515, RB935744, RB943538 and RB935744, respectively. The maxim yields of sugar (32.2 Mg ha^-1) and alcohol (23 m³ ha^-1) were obtained with variety RB935744 and water replenishment close to 110% of the ETc. Keywords: Saccharum officinarum, water efficiency, irrigation management.

Cowpea is a legume of great socioeconomic importance for the North and Northeast regions of Brazil. However, studies to evaluate its production performance when cultivated under irrigated regime and under different plant densities are necessary. The objective of this work was to evaluate the effects of different water regimes and different plant densities on grain yield, production components and water use efficiency, and on the correlation between grain yield and production components of BRS Tumucumaque cowpea cultivar. The experiment was carried out at Embrapa Meio-Norte experimental area, in Teresina, Piauí State, Brazil, from June to September 2017, in an Argissolo Vermelho-Amarelo eutrófico (Ultisol). A randomized complete block design was used, in a split-plot scheme with four replicates, in which the water regimes occupied the plots (187.7; 233.5; 263.5 and 288.7 mm) and plant densities, the subplots (12; 16; 20 and 24 plants m-2). The number of pods per plant, number of pods per square meter, pod length, dry grain yield and water use efficiency were evaluated. The maximum dry grain yield reached was 1,694.46 kg ha-1, with application of 288.7 mm and density of 20.4 plants m-2. The production component number of pods per square meter was the most correlated with dry grain yield.

The objective of this study was to evaluate the distribution of NO3 - and K+ in the profile of soils cultivated with sugarcane crops, after application of different nitrogen (N) and potassium (K2O) rates via subsurface drip fertigation, in Teresina, PI, Brazil. The experiment was conducted at the experimental area of Embrapa Meio-Norte, using a randomized block design with four replications. The treatments were arranged in split plots, with N+K2O rates (60+120, 180+120, 120+60, 120+180, and 120+120 kg ha-1 of N + K2O, respectively) in the plots, and soil layers (0.0-0.2, 0.2-0.4, and 0.4-0.6 m), for quantification of NO3- and K+ concentrations in the soil, in the subplots. The soil of the experimental area was a Typic Hapludult of sandy-loam texture. The distribution of nitrate (NO3-) and potassium (K+) in the soil layers after the N+K2O applications were evaluated. The NO3- and K+ concentrations in soils under sugarcane crops in the plant crop cycle is higher at the beginning and at the end of the cycle, respectively. The NO3 - and K+ concentrations in the soil solution are dependent on the evaluation time, soil layer, and N and K2O rates applied via fertigation. The highest concentrations of NO3- (264 mg L-1) and K+ (377 ppm) were found in the 0.0-0.2 m soil layer. No leaching of NO3- or K+ to deepest soil layers (>0.4 m) was found.

PRODUTIVIDADE DE COLMOS E EFICIÊNCIA DO USO DA ÁGUA EM CANA-DE-AÇÚCAR IRRIGADA POR GOTEJAMENTO SUBSUPERFICIAL     EDUARDO MAGNO PEREIRA DA SILVA¹; ADERSON SOARES DE ANDRADE JÚNIOR²; EDSON ALVES BASTOS² E VALDENIR QUEIROZ RIBEIRO^{2 1}Universidade Federal do Piauí (UFPI), Centro de Ciências Agrárias, Programa de Pós‑Graduação em Agronomia, Campus Socopo, Rua Dirce Oliveira, S/N, Ininga, CEP 64048‑550 Teresina, PI, Brasil. e-mail: agronomo_edu@yahoo.com.br  ²Embrapa Meio‑Norte, Avenida Duque de Caxias, n° 5.650, Bairro Buenos Aires, CEP 64006‑220 Teresina, PI. Brasil, e-mail: aderson.andrade@embrapa.br, edson.bastos@embrapa.br, valdenir.queiroz@embrapa.br     1 RESUMO   O objetivo desta pesquisa foi avaliar a produtividade de colmos e a eficiência de uso da água de variedades de cana-de-açúcar (cana planta) em resposta a diferentes regimes hídricos aplicados por gotejamento subsuperficial. O experimento foi realizado em um Argissolo Vermelho Amarelo distrófico, na Embrapa Meio-Norte, em Teresina, Piauí, Brasil, durante o período de outubro de 2015 a setembro de 2016. Utilizou-se o delineamento experimental de blocos casualizados em parcelas subdivididas, com quatro repetições. As parcelas foram constituídas por quatro regimes hídricos (irrigação mais precipitação pluviométrica) baseados em frações da evapotranspiração de cultura (50% ETc = 1.374,3; 80% ETc = 1.534,2; 110% ETc = 1.712,0 e 150% ETc = 1.905,8 mm) e as subparcelas por dez variedades de cana-de-açúcar (RBUFRPE01, RBUFRPE02, RBUFRPE03, RBUFV01, RB036066, RB987935, RB935744, RB943538, RB92579 e RB867515). A variação do regime hídrico promoveu alteração na performance produtiva e na eficiência do uso da água. A máxima produtividade de colmos (222,9 Mg ha^-1) foi obtida com a variedade RB935744 e a lâmina total aplicada de 1.688,8 mm. A maior eficiência do uso da água (13,5 kg m^-3) foi obtida com a variedade RB935744, aplicando-se lâmina total de 1.606,2 mm. Palavras-chave: Saccharum officinarum, performance produtiva, planejamento de irrigação. SILVA, E. M. P.; ANDRADE JÚNIOR, A. S.; BASTOS, E. A.; RIBEIRO, V. Q.STALKS YIELD AND WATER USE EFFICIENCY OF SUGARCANE IRRIGATED BY SUBSURFACE DRIPPING   This study aimed to evaluate stalks yield and water use efficiency of sugarcane varieties (cane plant) in response to different water regimes applied by subsurface drip irrigation. The experiment was carried out in a dystrophic Yellow Red Argisol at Embrapa Middle North, Teresina, Piauí State, Brazil, during the period from October 2015 to September 2016. The experiment was designed in a randomized block design in subdivided plots, with four replications. The plots consisted of four water regimes (irrigation plus rainfall) based on culture evapotranspiration fractions (50% ETc = 1,374.3 mm, 80% ETc = 1,534.2 mm, 110% ETc = 1,712.0 mm and 150% ETc = 1,905.8 mm) and subplots per ten varieties of sugarcane (RBUFRPE01, RBUFRPE02, RBUFRPE03, RBUFV01, RB036066, RB987935, RB935744, RB943538, RB92579 and RB867515). The variation of the water regime promoted a change in productive performance and water use efficiency. The maximum stalks yield (222.9 Mg ha^-1) was obtained with variety RB935744 and the total applied depth of 1,688.8 mm. The greater efficiency of water use (13.5 kg m^-3) was obtained with variety RB935744, applying total depth of 1,606.2 mm. Keywords: Saccharum officinarum, productive performance, irrigation planning.

The objective of this work was to evaluate the stalk yield, technological quality parameters, and sugar and alcohol productions in the first sugarcane (Saccharum officinarum) crop cycle, according to the response to N and K₂O applications by subsurface drip fertigation. The experiment was carried out in a dystrophic Ultisol, in a randomized complete block design with four replicates. The treatments consisted of a 2^X + 2X + 1 incomplete factorial arrangement with the application of 60, 80, 120, 160, and 180 kg ha^-1 N and 60, 80, 120, 160, and 180 kg ha^-1 K₂O. The maximum estimated yield (217.5 Mg ha^-1) was obtained with the application of 180 kg ha^-1 N and 60 kg ha^-1 K₂O. Sugar and alcohol productions increased with N application above 120 kg ha^-1. The technological quality characteristics of soluble solids content, apparent sucrose in the juice/broth, apparent sucrose in sugarcane, purity, and fiber show the highest averages with the application of 180 kg ha^-1 N and 60 kg ha^-1 K₂O.

The objective of this work was to obtain cowpea (Vigna unguiculata) progenies with compound inflorescences, short peduncles, early cycle, good plant architecture, and high-yielding potential. The initial genetic material consisted of 453 F-2(:3) progenies, selected from ten crosses and evaluated using Federer's augmented block design, with two controls. Of these, 60 progenies from the F-4(:5) and F-4(:6) generations were selected and assessed in two consecutive experiments, both in a 8x8 lattice design with four controls and four replicates. Early selection was efficient at fixing the evaluated traits. A wide genetic variability was detected among and within progenies. The estimated and obtained heritability and genetic gains in the F-4(:5) and F-4(:6) progenies indicate the possibility of selection of early progenies with short peduncles, compound inflorescences, and productivity similar to or greater than that of the commercial cultivars used as controls.

Cowpea bean is a socioeconomically important legume that contribute to generate employment and income. This species presents great grain variability, and the commercial subclass black eye stands out as a very appreciated grain in Brazil and abroad, thus requiring the development of new cultivars. The objective of this work was to evaluate and select lineages of commercial black eye cowpea, based on simultaneous, and direct selection. First, 105 progenies and four controls were evaluated using the Federer's augmented block design. Seventy-seven progenies, selected from this evaluation-first selection cycle-and four controls were evaluated in three environments, using a simple 9×9 lattice design. Based on this evaluation, the second selection cycle was possible, resulting in 24 progenies. The gain by direct selection was lower than the predicted gain for grain yield in the first cycle, indicating that the selection was not effective. This result was probably due to the reduced genetic variability caused by the selection pressure. In the second cycle, the predicted and observed gains were similar, indicating that much of the expected gain was observed. The predicted and observed gains, with simultaneous selection based on the rank sum selection index, were similar in the first and second cycle. The simultaneous and direct selections resulted in genetic gains for grain yield in the two selection cycles, making it possible the selection of high grain yield lineages.

Low grain yield of cowpea is influenced by several production factors, especially inadequate soil fertilization, in particular, phosphorus application. Tropical soils have low phosphorus and zinc levels due to either the source material or the absence of fertilization, which restricts cowpea grain yield; besides of that, zinc deficiency is accentuated with phosphor application. This study aimed to evaluate the effect of fertilization with phosphorus and zinc on cowpea yield. Two experiments were conducted, one with ‘BRS Guariba’ cultivar and another with ‘BRS Aracê’ cultivar. Both of them were performed on a medium-texture dystrophic Yellow Latosol (Oxisol), in the city of Magalhães de Almeida, Maranhão state (Brazil), in 2015. The experimental design was a randomized complete block in a 4 x 4 factorial scheme, using four doses of phosphorus (0, 40, 80, and 120 kg P2O5 ha-1), and four of zinc (0, 2, 4, and 6 kg of Zn ha-1). There was an interaction between these minerals (p<0.01). Maximum grain yields of 1,376 kg ha-1 and 2,165 kg ha-1 were obtained at doses of 118 kg P2O5 ha-1 and 0.9 kg zinc ha-1 for ‘BRS Guariba’, and 120 kg P2O5 ha-1 and 3.1 kg zinc ha-1 for ‘BRS Aracê’, respectively. The production component of greatest influence on grain yield was the number of pods per plant, with average values of 6 and 10 for ‘BRS Guariba’ and ‘BRS Aracê’ cultivars, respectively. The mean correlation coefficient was 0.82 (p < 0.01).

The aim of this study was to assess the productive performance of cowpea cultivars with different growth habits as a function of population density in the MATOPIBA region, Brazil. The experiments were carried out in Magalhães de Almeida, MA in the agricultural season 2014/2015. The cultivars BRS Itaim, BRS Tumucumaque, and BRS Pajeú, which present an erect, semi-erect, and semi-prostrate growth habits, respectively, were assessed. For the erect and semi-erect cultivars, a total of 8, 12, 16, 20, 24, and 28 plants m−2 were used whereas for the semi-prostrate cultivar, a total of 2, 6, 10, 14, 18, and 22 plants m−2 were used. The experimental design was a randomized block design with four replications and treatments composed of plant densities. Grain yield and number of pods per area presented a quadratic response to the increased plant density whereas a decreasing linear response was observed for the number of pods per plant. The maximum grain yield of erect, semi-erect, and semi-prostrate cultivars were 1,076 kg ha−1 (19.5 plants m−2), 1,252 kg ha−1 (18.7 plants m−2), and 755 kg ha−1 (14.5 plants m−2), respectively. The number of pods per area was the character that most correlated (P<0.01) with grain yield, regardless of the plant growth habit.