RESUMO Sistema consorciado e uso de adubação verde com espécies espontâneas tem sido um método alternativo de cultivo aplicado ao setor produtivo de hortaliças na região semiárida nordestina. O objetivo deste trabalho foi determinar qual quantidade de Calotropis procera deve ser incorporada ao solo para proporcionar o melhor desempenho produtivo das culturas componentes e aumentar a rentabilidade do consórcio de cenoura e caupi. O delineamento experimental utilizado foi de blocos completos casualizados com cinco repetições. Os tratamentos consistiram de quatro quantidades de C. procera incorporadas ao solo: 10, 25, 40 e 55 t ha-1, em base seca. As características avaliadas neste sistema consorciado foram: produtividade comercial de raízes de cenoura, produtividade de grãos verdes de caupi, índices de uso eficiente da terra das culturas componentes e do consórcio, escore da variável canônica da associação e os indicadores econômicos renda bruta, renda líquida, taxa de retorno e margem de lucro líquido. A máxima eficiência agronômica do consórcio cenoura x caupi foi alcançada no índice de uso eficiente da terra de 1,12, utilizando-se 43,39 t ha-1 de biomassa de C. procera incorporada ao solo, enquanto a eficiência econômica máxima da associação cenoura x caupi foi obtida com a renda líquida de R$ 17.856,43 ha-1, na quantidade de 40,60 t ha-1 de biomassa de C. procera adicionada ao solo. | ABSTRACT Intercropping system and the use of green manure with spontaneous species has been an alternative farming method applied to the productive sector of vegetables in the northeastern semi-arid region. The objective of this work was to determine which amount of Calotropis procera must be incorporated into the soil to provide the highest productive performance of the component crops and increase the profitability of the carrot and cowpea intercropping. The experimental design used was randomized complete blocks with five replicates. The treatments consisted of four amounts of C. procera incorporated into the soil: 10, 25, 40 and 55 t ha-1 on a dry basis. The characteristics evaluated in this intercropping system were: commercial productivity of carrot roots, yield of cowpea green grains, land equivalent ratios for component crops and for the intercropped system, score of the canonical variable of the association, and the economic indicators of gross income, net income, rate of return, and net profit margin. The maximum agronomic efficiency of the carrot x cowpea intercropping was reached at the land equivalent ratio of 1.12, using 43.39 t ha-1 of C. procera biomass incorporated in the soil, while the maximum economic efficiency of the carrot and cowpea crops association was obtained at the net income of R$ 17,856.43 ha-1, in the amount of 40.60 t ha-1 of C. procera biomass added to the soil.

Intercropping system and the use of green manure with spontaneous species has been an alternative farming method applied to the productive sector of vegetables in the northeastern semi-arid region. The objective of this work was to determine which amount of Calotropis procera must be incorporated into the soil to provide the highest productive performance of the component crops and increase the profitability of the carrot and cowpea intercropping. The experimental design used was randomized complete blocks with five replicates. The treatments consisted of four amounts of C. procera incorporated into the soil: 10, 25, 40 and 55 t ha-1 on a dry basis. The characteristics evaluated in this intercropping system were: commercial productivity of carrot roots, yield of cowpea green grains, land equivalent ratios for component crops and for the intercropped system, score of the canonical variable of the association, and the economic indicators of gross income, net income, rate of return, and net profit margin. The maximum agronomic efficiency of the carrot x cowpea intercropping was reached at the land equivalent ratio of 1.12, using 43.39 t ha-1 of C. procera biomass incorporated in the soil, while the maximum economic efficiency of the carrot and cowpea crops association was obtained at the net income of R$ 17,856.43 ha-1, in the amount of 40.60 t ha-1 of C. procera biomass added to the soil.

RESUMO O arranjo espacial e a densidade populacional das culturas componentes quando bem estruturados podem contribuir para aumentar os rendimentos das culturas em relação ao monocultivos. Assim, o objetivo deste trabalho foi avaliar o desempenho produtivo da cenoura e do feijão-caupi em sistema consorciado sob diferentes arranjos espaciais e densidades populacionais. Essa pessquisa foi conduzida na fazenda experimental "Rafael Fernandes" da Universidade Federal Rural do Semi-Árido (UFERSA), Mossoró, RN, Brasil. O delineamento experimental foi de blocos completos casualizados com quatro repetições, em esquema fatorial 3 x 4 em que o primeiro fator foi três arranjos espaciais (2: 2, 3:3 e 4:4) e o segundo fator quatro densidades populacionais de feijão-caupi (100, 80, 60 e 40% da população recomendada no cultivo solteiro - PRCS). O experimento foi adubado com flor-de-seda (Calotropis procera (Ait.) R.Br.), uma espécie espontânea do bioma Caatinga. As características avaliadas na cenoura foram: produtividade total e comercial de raízes e produtividade classificada de raízes. Para o feijão-caupi foi avaliado as seguintes características: número de vagens por metro quadrado, comprimento e produtividade de vagens verdes, número de grãos por vagem, peso de 100 grãos e produtividade de grãos verdes. A vantagem monetária corrigida foi utilizada para avaliar a viabilidade dos sistemas consorciados. Não se observou influencia dos arranjos espaciais entre as culturas componentes no desempenho agroeconômico do consórcio de cenoura x feijão-caupi. A mais alta performance agroeconômica do consórcio cenoura x feijão-caupi foi obtida na densidade populacional de caupi de 42% da PRCS. | ABSTRACT Spatial arrangement and population density of component cultures, when well structured, may contribute to increased crop yields relative to monocultures. Thus, the objective of this work was to evaluate the productive performance of carrot and cowpea in an intercropping system under different spatial arrangements and population densities. This research was conducted on the “Rafael Fernandes” experimental farm of the Universidade Federal Rural do Semi-Árido (UFERSA), Mossoró, RN, Brazil. The experimental design was a randomized complete block with four replicates, where the treatments were arranged in a 3 × 4 factorial scheme, in which the first factor was three spatial arrangements (2:2, 3:3, and 4:4) and the second factor was four different population densities of cowpea (100%, 80%, 60%, and 40% of the recommended population in the single crop [RPSC]). Rooster tree Calotropis procera (Ait.) R.Br., a spontaneous species of the „Caatinga‟ biome, was used as fertilizer. The characteristics evaluated in carrot were as follows: total and commercial productivity of roots and classified root production. The following characteristics were evaluated for cowpea: number of pods per square meter, length and yield of green pods, number of grains per pod, 100grain weight, and yield of green grains. The modified monetary advantage was used to evaluate the feasibility of the intercropped systems. Spatial arrangements between the component cultures did not influence the agroeconomic performance of the carrot-cowpea intercropping system. The highest agro-economic performance of the carrot-cowpea intercropping was obtained in the population of cowpea, which was 42% of the RPSC.

Spatial arrangement and population density of component cultures, when well structured, may contribute to increased crop yields relative to monocultures. Thus, the objective of this work was to evaluate the productive performance of carrot and cowpea in an intercropping system under different spatial arrangements and population densities. This research was conducted on the “Rafael Fernandes” experimental farm of the Universidade Federal Rural do Semi-Árido (UFERSA), Mossoró, RN, Brazil. The experimental design was a randomized complete block with four replicates, where the treatments were arranged in a 3 × 4 factorial scheme, in which the first factor was three spatial arrangements (2:2, 3:3, and 4:4) and the second factor was four different population densities of cowpea (100%, 80%, 60%, and 40% of the recommended population in the single crop RPSC). Rooster tree Calotropis procera (Ait.) R.Br., a spontaneous species of the „Caatinga‟ biome, was used as fertilizer. The characteristics evaluated in carrot were as follows: total and commercial productivity of roots and classified root production. The following characteristics were evaluated for cowpea: number of pods per square meter, length and yield of green pods, number of grains per pod, 100grain weight, and yield of green grains. The modified monetary advantage was used to evaluate the feasibility of the intercropped systems. Spatial arrangements between the component cultures did not influence the agroeconomic performance of the carrot-cowpea intercropping system. The highest agro-economic performance of the carrot-cowpea intercropping was obtained in the population of cowpea, which was 42% of the RPSC.

ABSTRACT Cowpea is one of the major food crops in Northeast Brazil, where it is commonly cultivated in the semi-arid regions with limited water availability. It is important to study the elicitors associated with cowpea to mitigate any deleterious effects of abiotic stress on the initial establishment of this crop. In this study, we aimed to evaluate the morphophysiological changes in cowpea cultivars under osmotic stress with seeds soaked in salicylic acid. The germination test was conducted in B.O.D germination chambers. The seeds of three cowpea cultivars: BRS Tumucumaque, BRS Aracê, and BRS Guariba, were germinated at five osmotic potentials (0.0; -0.2; -0.4; -0.6, and -0.8 MPa) after three pre-treatments: pre-soaking in deionized water, pre-soaking in salicylic acid, and without pre-soaking. The following parameters were evaluated: germination, germination speed index, seedling height, total phytomass, contents of chlorophyll ‘a’ and ‘b’, carotenoid content, electrolyte leakage, water content, and proline content. Our results indicate that salicylic acid promotes reduction in the harmful effects of abiotic stress, which is reflected in the increase in germination percentage, seedling height, and chlorophyll and carotenoid content as well as in the adjustment of electrolyte leakage and increase in proline content under induced water stress conditions. The cultivar BRS Guariba proved to be more tolerant to water deficit during germination and initial growth stages, when the seeds were treated with salicylic acid (1 mM). | RESUMO O feijão-caupi é uma das principais culturas alimentares no Nordeste do Brasil, onde é geralmente cultivada nas regiões semiáridas com pouca disponibilidade de água. É importante estudar os elicitores associados ao caupi para mitigar os efeitos deletérios do estresse abiótico no estabelecimento inicial desta cultura. Neste estudo, buscaram-se avaliar as alterações morfofisiológicas em cultivares de caupi sob estresse osmótico com sementes embebidas em ácido salicílico. O teste de germinação foi realizado em câmaras de germinação B.O.D. As sementes de três cultivares de caupi: BRS Tumucumaque, BRS Aracê e BRS Guariba foram germinadas em cinco potenciais osmóticos (0,0; -0,2; -0,4; -0,6 e -0,8 MPa) após três pré-tratamentos: pré-imersão em Água desionizada, pré-imersão em ácido salicílico e sem pré-imersão. Foram avaliados os seguintes parâmetros: germinação, índice de velocidade de germinação, altura da plântula, fitometria total, conteúdo de clorofila 'a' e 'b', conteúdo de carotenóides, vazamento eletrolítico, teor de água e conteúdo de prolina. Os resultados indicam que o ácido salicílico promove a redução dos efeitos nocivos do estresse abiótico, o que se reflete no aumento da porcentagem de germinação, altura da plântula e teor de clorofila e carotenóides, bem como no ajuste do vazamento eletrolítico e aumento do teor de prolina sob condições de estresse hídrico. A cultivar BRS Guariba mostrou-se mais tolerante ao déficit de água durante a germinação e estágios de crescimento inicial, quando as sementes foram tratadas com ácido salicílico (1 mM).

Cowpea is one of the major food crops in Northeast Brazil, where it is commonly cultivated in the semi-arid regions with limited water availability. It is important to study the elicitors associated with cowpea to mitigate any deleterious effects of abiotic stress on the initial establishment of this crop. In this study, we aimed to evaluate the morphophysiological changes in cowpea cultivars under osmotic stress with seeds soaked in salicylic acid. The germination test was conducted in B.O.D germination chambers. The seeds of three cowpea cultivars: BRS Tumucumaque, BRS Aracê, and BRS Guariba, were germinated at five osmotic potentials (0.0; -0.2; -0.4; -0.6, and -0.8 MPa) after three pre-treatments: pre-soaking in deionized water, pre-soaking in salicylic acid, and without pre-soaking. The following parameters were evaluated: germination, germination speed index, seedling height, total phytomass, contents of chlorophyll ‘a’ and ‘b’, carotenoid content, electrolyte leakage, water content, and proline content. Our results indicate that salicylic acid promotes reduction in the harmful effects of abiotic stress, which is reflected in the increase in germination percentage, seedling height, and chlorophyll and carotenoid content as well as in the adjustment of electrolyte leakage and increase in proline content under induced water stress conditions. The cultivar BRS Guariba proved to be more tolerant to water deficit during germination and initial growth stages, when the seeds were treated with salicylic acid (1 mM).

ABSTRACT The most-used preparation process of protein isolates (PI) involves the isoelectric precipitation of the protein. Heating shortens the preparation time but this procedure may affect the purity, yield, molecular profile of the protein, and the activity of the trypsin inhibitor. This study aimed to investigate the effect of heating in the production of cowpea protein isolates. Crude whole beans (WB) were defatted with hexane, and the protein isolates obtained by isoelectric precipitation with (HPI), and without (NHPI) heating. The protein content of the WB and the PI was determined by the micro-Kjeldahl method, and the extraction yield estimated from the protein content at the end of extraction in relation to this content in the raw material. Possible losses of protein fractions were followed by SDS-PAGE, and the trypsin inhibitor activity determined by an enzymatic assay (BAPNA: benzoyl-DL-arginine-p-nitroanilide). Protein content in HPI was 83.3%, less than in the NHPI (92.2%). The HPI yield was lower (40.0%) as compared to the NHPI (42.3%). Electrophoresis indicated bands ranging from 13 to 262 kDa in WB; and the NHPI presented a protein fraction’s profile closer to that of the WB than to the HPI. The WB had the trypsin inhibitor activity, expressed as Trypsin Inhibitory Units (TIU), of 32.5±0.5 TIU /mg-protein; HPI showed 12.7±0.5 TIU /mg-protein (39% of that observed in WB) and the NHPI, 8.3±0.2 TIU /mg-protein (25.5%). Heating reduces the yield and purity of proteins in the isolates. However, the inhibitory activity of trypsin cowpea is most affected by the isolation procedure. | RESUMO O processo mais utilizado na preparação de isolado proteico (IP) envolve a precipitação isoelétrica da proteína. O aquecimento abrevia o tempo de preparo dos isolados. Entretanto, esse procedimento pode afetar a pureza, rendimento, perfil molecular da proteína e presença do inibidor de tripsina. Este trabalho objetivou investigar o efeito do aquecimento na produção de IP de feijão-caupi. O feijão integral (FI) cru foi moído e desengordurado com hexano e o IP foi obtido por precipitação isoelétrica com aquecimento (IPCA) e sem aquecimento (IPSA). Determinou-se o teor proteico do FI, e dos isolados pelo método de micro-Kjeldahl. Estimou-se o rendimento da extração, pela massa de proteína ao final da extração em relação à existente inicialmente no material seco. Possíveis perdas de frações proteicas foram avaliadas por eletroforese SDS-PAGE. A atividade inibitória da tripsina foi avaliada em ensaio enzimático (BAPNA: benzoil-DLarginina-p-nitroanilida). Obteve-se um IPCA (83,3% de proteína), menos puro que o IPSA (92,2%). O rendimento do IPCA foi menor (40,0%) em relação ao IPSA (42,3%). A eletroforese indicou bandas variando de 13 a 262 kDa no FI, o IPSA apresentou um perfil de frações proteicas mais próximo ao FI que o IPCA. O FI apresentou atividade inibitória, expressa em Unidades Inibitórias de Tripsina (UIT) de 32,5±0,5UIT/mg-proteína, o IPCA apresentou 12,7±0,5UIT/mg-proteína (39% do observado no FI) e, o IPSA, 8,3±0,2 UIT/mg-proteína (25,5%). O aquecimento reduz o rendimento e a pureza da proteína nos isolados. Entretanto, a atividade inibitória da tripsina é mais afetada pelo processo de isolamento.

The most-used preparation process of protein isolates (PI) involves the isoelectric precipitation of the protein. Heating shortens the preparation time but this procedure may affect the purity, yield, molecular profile of the protein, and the activity of the trypsin inhibitor. This study aimed to investigate the effect of heating in the production of cowpea protein isolates. Crude whole beans (WB) were defatted with hexane, and the protein isolates obtained by isoelectric precipitation with (HPI), and without (NHPI) heating. The protein content of the WB and the PI was determined by the micro-Kjeldahl method, and the extraction yield estimated from the protein content at the end of extraction in relation to this content in the raw material. Possible losses of protein fractions were followed by SDS-PAGE, and the trypsin inhibitor activity determined by an enzymatic assay (BAPNA: benzoyl-DL-arginine-p-nitroanilide). Protein content in HPI was 83.3%, less than in the NHPI (92.2%). The HPI yield was lower (40.0%) as compared to the NHPI (42.3%). Electrophoresis indicated bands ranging from 13 to 262 kDa in WB; and the NHPI presented a protein fraction’s profile closer to that of the WB than to the HPI. The WB had the trypsin inhibitor activity, expressed as Trypsin Inhibitory Units (TIU), of 32.5±0.5 TIU /mg-protein; HPI showed 12.7±0.5 TIU /mg-protein (39% of that observed in WB) and the NHPI, 8.3±0.2 TIU /mg-protein (25.5%). Heating reduces the yield and purity of proteins in the isolates. However, the inhibitory activity of trypsin cowpea is most affected by the isolation procedure.

ABSTRACT Flour production through milling is an alternative for the cowpea processing, when the aim is to obtain a product with higher added value. The objective of this work was to determine the chemical composition, the granulometry, and evaluate the microbiological characteristics of whole-bean flours from five cowpea cultivars (BRS Cauamé, BRS Guariba, BRS Xiquexique, BRS Novaera and BRS Itaim). Cowpea beans were dried in a oven (Fanem, 320-SE) at 50 °C for 6 hours, milled in a cyclone-type rotor mill (Tecnal, TE-651/2) and, subsequently, in a pulverizer-type semi-industrial mill (Fritsch, Pulverisette 14) to obtain the flour. The flour centesimal composition, total energetic value, mineral content, granulometry, microbiological characteristics, and technological properties-flour water absorption and solubility in water-were analyzed. All analyzes were performed in triplicate and the results expressed in mean ± standard deviation. The means were compared by the Scott-Knott test (p ≤ 0.05). The flour centesimal composition presented (g per 100 g of flour): 7.13 to 10.33 of moisture, 2.06 to 3.65 of ashes, 1.53 g to 2.90 of lipids, 21.73 to 25.77 of proteins, and 58.08 to 64.02 of carbohydrate. The flours had on average 359.04 Kcal (100 g) and presented high iron, zinc, copper, manganese, phosphorus and magnesium contents. The whole-bean flours from the cultivars BRS Cauamé and BRS Xiquexique are sources of calcium. Regarding the microbiological characteristics, all flours are innocuous. The water absorption index were within 1.77 and 2.20 g g-1 and the water solubility index within 17 and 23%. All whole-bean flours had good nutritional, technological and microbiological characteristics, and thus potential for use in bakery products. | RESUMO A produção de farinha por meio da moagem é uma alternativa para o processamento do feijão-caupi, na busca de um produto com maior valor agregado. Objetivou-se determinar a composição química, a granulometria e avaliar microbiologicamente farinhas integrais de cinco cultivares (BRS Cauamé, BRS Guariba, BRS Xiquexique, BRS Novaera e BRS Itaim) comerciais de feijão-caupi. Para a obtenção das farinhas procedeu-se a secagem dos grãos em estufa (marca Fanem, modelo 320-SE) a 50 °C, por 6 horas; com posterior moagem, primeiramente em moinho de facas tipo ciclone (marca Tecnal, modelo TE-651/2) e posteriormente, em moinho semi-industrial tipo pulverizador (marca Fritsch, modelo Pulverisette 14). Analisaram-se a composição centesimal, o valor energético total, o conteúdo mineral, a granulometria, as características microbiológicas, e as tecnológicas quanto a absorção e solubilidade em água das farinhas. As análises foram realizadas em triplicata e os resultados expressos em média ± desvio padrão. As médias foram comparadas pelo teste de Scott-Knott (p≤0,05). Os valores encontrados para composição centesimal foram: umidade entre 7,13 a 10,33 g/100g; cinzas de 2,06 a 3,65 g/100g; lipídios variaram de 1,53 g a 2,90 g/100g; proteínas entre 21,73 a 25,77 g/100g e o conteúdo de carboidratos variou de 58,08 a 64,02 g/100g. As farinhas ofertaram em média 359,04 Kcal/100g e apresentaram elevado teor de ferro, zinco, cobre, manganês, fósforo e magnésio, sendo as das cultivares BRS Cauamé e BRS Xiquexique fontes de cálcio. Sob o aspecto microbiológico as farinhas apresentaram-se inócuas. Os valores de IAA variaram de 1,77 a 2,20 g/g e ISA de 17 a 23%. Concluiu-se que todas as farinhas apresentaram bom perfil nutritivo, tecnológico e microbiológico, apresentando, portanto potencial para utilização no desenvolvimento de produtos de panificação.

Flour production through milling is an alternative for the cowpea processing, when the aim is to obtain a product with higher added value. The objective of this work was to determine the chemical composition, the granulometry, and evaluate the microbiological characteristics of whole-bean flours from five cowpea cultivars (BRS Cauamé, BRS Guariba, BRS Xiquexique, BRS Novaera and BRS Itaim). Cowpea beans were dried in a oven (Fanem, 320-SE) at 50 °C for 6 hours, milled in a cyclone-type rotor mill (Tecnal, TE-651/2) and, subsequently, in a pulverizer-type semi-industrial mill (Fritsch, Pulverisette 14) to obtain the flour. The flour centesimal composition, total energetic value, mineral content, granulometry, microbiological characteristics, and technological properties-flour water absorption and solubility in water-were analyzed. All analyzes were performed in triplicate and the results expressed in mean ± standard deviation. The means were compared by the Scott-Knott test (p ≤ 0.05). The flour centesimal composition presented (g per 100 g of flour): 7.13 to 10.33 of moisture, 2.06 to 3.65 of ashes, 1.53 g to 2.90 of lipids, 21.73 to 25.77 of proteins, and 58.08 to 64.02 of carbohydrate. The flours had on average 359.04 Kcal (100 g) and presented high iron, zinc, copper, manganese, phosphorus and magnesium contents. The whole-bean flours from the cultivars BRS Cauamé and BRS Xiquexique are sources of calcium. Regarding the microbiological characteristics, all flours are innocuous. The water absorption index were within 1.77 and 2.20 g g-1 and the water solubility index within 17 and 23%. All whole-bean flours had good nutritional, technological and microbiological characteristics, and thus potential for use in bakery products.

ABSTRACT The effects of biochar and nitrogen application on yields of upland rice and cowpea and on soil fertility were determined in a greenhouse in Macaíba, RN, Brazil. The trial consisted of the succession of two crops in a completely randomized design and a factorial scheme, with four replicates. Initially, four doses of biochar and four doses of nitrogen were tested for cultivation of rice. Subsequently, four doses of biochar and two doses of nitrogen were tested in half of the pots maintained for planting cowpea. Soil was sampled after rice harvest for half of the pots and at end of the trial for the remaining pots. We evaluated the following parameters: mass of hundred grains of rice, dry shoot mass, panicle number, number of filled spikelets and of empty spikelets, and grain production. Determinations for cowpea were: pod number per pot, grain number per pod, and grain production per pot. Measured soil parameters were: pH, contents of organic carbon, P, K, Ca, Mg, Na, cation exchange capacity, and exchangeable sodium percentage. Biochar addition did not influence yield components of upland rice and cowpea, but resulted in increased soil N retention, which influenced rice dry shoot mass, spikelets sterility, panicle number, and grain mass. Biochar also promoted increased soil pH, potassium content, and exchangeable sodium percentage and decreased calcium and magnesium concentrations. | RESUMO Os efeitos da aplicação de carvão vegetal e nitrogênio sobre a produtividade de arroz de terras altas e feijão-caupi e a fertilidade do solo foram determinados em ambiente protegido em Macaíba, RN, Brasil. O experimento constou de dois cultivos sucessivos em delineamento experimental completamente casualizado em arranjo fatorial, com quatro repetições. Inicialmente, foram testadas quatro doses de carvão vegetal e quatro de nitrogênio para a cultura do arroz. A seguir, foi cultivado feijão-caupi em metade dos vasos (quatro doses de carvão e duas de nitrogênio). O solo foi amostrado após a colheita do arroz, em metade dos vasos, e ao final do experimento, nos vasos restantes. Do arroz foram determinados, massa de cem grãos e, por vaso, massa seca da parte aérea, número de panículas, número de grãos cheios e grãos vazios e produção de grãos. Do feijão-caupi foram determinados: número de vagens por vaso, número de grãos por vagem e produção de grãos por vaso. No solo foram determinados: pH, teores de carbono orgânico, P, K, Ca, Mg e Na, capacidade de troca de cátions e percentagem de sódio trocável. As doses de carvão vegetal não influenciaram nas características de produção do arroz e feijão-caupi, mas favoreceram a retenção de nitrogênio no solo, que se refletiu sobre massa seca da parte aérea do arroz, esterilidade das espiguetas, número de panículas e massa dos grãos. Além disso, promoveram aumento no pH, teor de potássio e percentagem de sódio trocável do solo, com diminuição no teor de cálcio e magnésio.

The effects of biochar and nitrogen application on yields of upland rice and cowpea and on soil fertility were determined in a greenhouse in Macaíba, RN, Brazil. The trial consisted of the succession of two crops in a completely randomized design and a factorial scheme, with four replicates. Initially, four doses of biochar and four doses of nitrogen were tested for cultivation of rice. Subsequently, four doses of biochar and two doses of nitrogen were tested in half of the pots maintained for planting cowpea. Soil was sampled after rice harvest for half of the pots and at end of the trial for the remaining pots. We evaluated the following parameters: mass of hundred grains of rice, dry shoot mass, panicle number, number of filled spikelets and of empty spikelets, and grain production. Determinations for cowpea were: pod number per pot, grain number per pod, and grain production per pot. Measured soil parameters were: pH, contents of organic carbon, P, K, Ca, Mg, Na, cation exchange capacity, and exchangeable sodium percentage. Biochar addition did not influence yield components of upland rice and cowpea, but resulted in increased soil N retention, which influenced rice dry shoot mass, spikelets sterility, panicle number, and grain mass. Biochar also promoted increased soil pH, potassium content, and exchangeable sodium percentage and decreased calcium and magnesium concentrations.

ABSTRACT The precocity of cowpea is important because it indicates the possibility of increasing and/or stabilizing production in regions with long periods of drought. The aim of this study was to evaluate genetic variability and select extra-early cowpea progenies. Fifteen F3:6 progenies were evaluated in 2014 while sixty-two F7 progenies were evaluated in 2015. Two commercial cultivars were used in experiments performed in the irrigated perimeter of Baixo Acaraú, in Marco, CE. The following characteristics were evaluated: number of days for flowering (NDF), number of days for maturity (NDM), plant height (PH), pod length (PL), number of seeds per pod (NSP), number of grains per plant (NGP), weight of 100 grains (W100G) and total weight (MTOT). Data were analyzed in lattice and RBD, according to the methodology of mixed models by the REML/BLUP procedure. Also, the components of variance and genetic values were estimated. Variability among progenies, high heritability and high accuracy were identified for all traits. For NDF and NDM, the progenies presented higher behavior than the controls. The lattice arrangement contributed to a greater gain with the selection of NDF, NDM, PH, NSP, NGP and WTOT. The genotypes 12, 15, 30, 33, 41, 43 and 52 are among the top ten because they have high genetic values in three or more traits. The genotypes 12, 15, 30, 33, 43 and 52 highlight extra-earliness (precocity). | RESUMO A precocidade é importante para o feijão-caupi por representar a possibilidade de aumentar e/ou estabilizar a produção em regiões com longos períodos de estiagem. Objetivou- se avaliar a variabilidade genética e selecionar progênies de feijão-caupi extraprecoces. Foram avaliadas 15 progênies F3:6 em 2014 e 62 progênies F7 em 2015, juntamente com duas cultivares comerciais em experimentos conduzidos no perímetro irrigado Baixo Acaraú, localizado no município de Marco, CE. Foram avaliados os caracteres: número de dias para o florescimento (NDF), número de dias para a maturação (NDM), altura de planta (ALT), comprimento de vagem (CPV), número de grãos por vagem (NGV), número de grãos por planta (NGP), massa de 100 grãos (M100G) e massa total (MTOT). Os dados foram analisados em DBIL e DBC, segundo a metodologia de modelos mistos, via procedimento REML/BLUP. Foram estimados os componentes de variância e os valores genéticos. Identificou-se variabilidade entre as progênies, alta herdabilidade e elevada acurácia em todos os caracteres avaliados. As progênies apresentaram comportamento superior às testemunhas para NDF e NDM. O arranjo em látice apresentou maior eficiência que o DBC, pelo maior ganho obtido com a seleção nos caracteres NDF, NDM, ALT, NGV, NGP e MTOT. Os genótipos 12, 15, 30, 33, 41, 43 e 52 encontram-se entre os dez superiores, por apresentarem valores genéticos elevados em três ou mais caracteres. Os genótipos 12, 15, 30, 33, 43 e 52 destacam-se como os mais precoces.

The precocity of cowpea is important because it indicates the possibility of increasing and/or stabilizing production in regions with long periods of drought. The aim of this study was to evaluate genetic variability and select extra-early cowpea progenies. Fifteen F3:6 progenies were evaluated in 2014 while sixty-two F7 progenies were evaluated in 2015. Two commercial cultivars were used in experiments performed in the irrigated perimeter of Baixo Acaraú, in Marco, CE. The following characteristics were evaluated: number of days for flowering (NDF), number of days for maturity (NDM), plant height (PH), pod length (PL), number of seeds per pod (NSP), number of grains per plant (NGP), weight of 100 grains (W100G) and total weight (MTOT). Data were analyzed in lattice and RBD, according to the methodology of mixed models by the REML/BLUP procedure. Also, the components of variance and genetic values were estimated. Variability among progenies, high heritability and high accuracy were identified for all traits. For NDF and NDM, the progenies presented higher behavior than the controls. The lattice arrangement contributed to a greater gain with the selection of NDF, NDM, PH, NSP, NGP and WTOT. The genotypes 12, 15, 30, 33, 41, 43 and 52 are among the top ten because they have high genetic values in three or more traits. The genotypes 12, 15, 30, 33, 43 and 52 highlight extra-earliness (precocity).

ABSTRACT This work evaluated the effect of soil water availability on growth and productivity variables of cowpea in northeastern Pará, Brazil. The experiment was carried out in a field of 2,100 m2 at the experimental site of the Federal Rural University of Amazon, during the driest season of the years 2011, 2012 and 2013, in a completely randomised design with two treatments (irrigated and non-irrigated), both with 12 replications in the reproductive phase (2012 and 2013). Growth and productivity data were submitted to analysis of variance with two variation factors (water regime and experimental year) at 5% probability. Student's t -test at 5% probability was used in the means of the stomatal conductance data, since this was monitored only in 2012. Final biomass production presented a reduction of 54.3% in 2012 and 26.4% in 2013 as a result of water deficit (DEF) of 76 and 26 mm, respectively. Mean stomatal conductance was reduced by 73% in the grain-filling stage as a result of the lower water availability during this period. Average cowpea productivity under water deficit reached 1,257 kg ha-1 in 2012 and 1,396 kg ha-1 in 2013. The reduction in water supply over the reproductive period significantly decreased production by 72 and 41% (F test, p < 0.05) in 2012 and 2013, respectively. An accumulated water deficit during the reproductive phase caused a maximum LAI reduction of 47% in 2012 (DEF of 76 mm) and of 13% in 2013 (DEF of 26 mm). | RESUMO O objetivo deste trabalho foi avaliar o efeito da disponibilidade de água no crescimento e produtividade do feijão-caupi cultivado no Nordeste do estado do Pará, Brasil. O experimento foi realizado em uma área de 2.100 m2 na Fazenda Escola da Universidade Federal Rural da Amazônia, durante o período menos chuvoso de 2011, 2012 e 2013, em um delineamento inteiramente casualizado com dois tratamentos (irrigado e não irrigado), com 12 repetições na fase reprodutiva (2012 e 2013). Dados de crescimento e de produtividade foram submetidos a análise de variância com dois fatores de variação (regime hídrico e ano experimental) a 5% de probabilidade. Utilizou-se o teste t de Student a 5% de probabilidade nas médias de condutância estomática por ser monitorada apenas em 2012. A produção final de biomassa apresentou redução de 54,3% em 2012 e de 26,4% em 2013 devido a ocorrência de uma deficiência hídrica (DEF) de 76 e de 26 mm, respectivamente. A condutância estomática média foi reduzida em 73% na fase de enchimento de grãos devido a menor disponibilidade de água nesta fase. A produtividade média do caupi sob baixa deficiência hídrica atingiu 1.257 kg ha-1 em 2012 e 1.396 kg ha-1 e 2013. A redução da água diminuiu em 72% e 41% o rendimento do caupi (teste F, p < 0,05) em 2012 e 2013, respectivamente. A deficiência hídrica acumulada na fase reprodutiva causou redução de 47% no máximo IAF em 2012 (DEF de 76 mm) e de 13% em 2013 (DEF de 26 mm).

This work evaluated the effect of soil water availability on growth and productivity variables of cowpea in northeastern Pará, Brazil. The experiment was carried out in a field of 2,100 m2 at the experimental site of the Federal Rural University of Amazon, during the driest season of the years 2011, 2012 and 2013, in a completely randomised design with two treatments (irrigated and non-irrigated), both with 12 replications in the reproductive phase (2012 and 2013). Growth and productivity data were submitted to analysis of variance with two variation factors (water regime and experimental year) at 5% probability. Student's t -test at 5% probability was used in the means of the stomatal conductance data, since this was monitored only in 2012. Final biomass production presented a reduction of 54.3% in 2012 and 26.4% in 2013 as a result of water deficit (DEF) of 76 and 26 mm, respectively. Mean stomatal conductance was reduced by 73% in the grain-filling stage as a result of the lower water availability during this period. Average cowpea productivity under water deficit reached 1,257 kg ha-1 in 2012 and 1,396 kg ha-1 in 2013. The reduction in water supply over the reproductive period significantly decreased production by 72 and 41% (F test, p < 0.05) in 2012 and 2013, respectively. An accumulated water deficit during the reproductive phase caused a maximum LAI reduction of 47% in 2012 (DEF of 76 mm) and of 13% in 2013 (DEF of 26 mm).