RESUMO A baixa produtividade de grãos do feijão-caupi é influenciada por vários fatores do processo produtivo, principalmente a inadequada fertilização do solo, em especial a fosfatagem. Os solos tropicais apresentam baixos teores de fósforo e de zinco, seja em função do material de origem ou pela ausência de adubação, o que restringe a produtividade do feijão-caupi. A deficiência de zinco se acentua em função da aplicação de fósforo. Este trabalho objetivou avaliar o efeito da adubação com doses de fósforo e zinco na produção de feijão-caupi. Foram conduzidos dois experimentos, sendo um com a cultivar ‘BRS Guariba’ e o outro com a cultivar ‘BRS Aracê’, ambos em um Latossolo Amarelo Distrófico de textura média, no município de Magalhães de Almeida, Maranhão, ano 2015, em delineamento experimental de blocos casualizados, em esquema fatorial 4 x 4, utilizando quatro doses de fósforo (0; 40; 80 e 120 kg de P2O5 ha-1) e quatro de zinco (0; 2; 4 e 6 kg de zinco ha-1). Houve interação entre esses minerais (p < 0,01) e foram obtidas produtividades máximas de 1.376 kg ha-1 e de 2.165 kg ha-1 com aplicações de doses de 118 kg de P2O5 ha-1 e de 0,9 kg de zinco ha-1, para a cultivar ‘BRS Guariba’ e 120 kg de P2O5 e de 3,1 kg de zinco ha-1 para a cultivar ‘BRS Aracê’, respectivamente. O componente de produção que mais influenciou a produtividade de grãos foi o número de vagens por planta, com valores médios de 6 e 10 para as cultivares ‘BRS Guariba’ e ‘BRS Aracê’, respectivamente, e coeficiente de correlação médio de 0,82 (p < 0,01). | ABSTRACT 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).

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).

ABSTRACT Leguminous species can improve nutrient cycling and chemical quality of Oxisols, resulting in higher productivity of intercropped crops. Thus, this research aimed to evaluate the decomposition rate and nutrient accumulation in legume stubble, as well as its contribution to soil chemical attributes, the growth of baru trees (Dipteryx alata Vogel), and yield of intercropped maize in an agroforestry system. The experiment was developed during the crop years of 2010-2011 and 2011-2012, in Goiás State, Brazil. The experimental design was a randomized block with five replicates. Leguminous species consisted of sunn hemp (Crotalaria juncea), jack bean (Canavalia ensiformis), pigeon pea (Cajanus cajan), Stylosanthes (Stylosanthes macrocephala - 20% and Stylosanthes capitata - 80%), and spontaneous vegetation (control treatment). The decomposition rates of legume and spontaneous vegetation residues remained unchanged in the agroforestry system. Sunn hemp, jack bean, and Stylosanthes plants are advantageous options for total accumulation of nutrients. However, sunn hemp grown as straw cover for next crop seasons increases the available phosphorus levels in the soil and productivity of maize cobs. With this coverage, maize productivity values were up to 24% higher than were those with maize growing on spontaneous vegetation, besides having no effect on the growth of baru trees. | RESUMO O uso de espécies leguminosas poderá favorecer a ciclagem de nutrientes e a qualidade química dos latossolos, o que de certa forma promoverá maior desempenho dos cultivos consorciados. Desta forma, objetivou-se com esta pesquisa avaliar a taxa de decomposição e o acúmulo de nutrientes em leguminosas, além dos atributos químicos do solo, crescimento de barueiros e produtividade de milho cultivados em rotação no sistema agroflorestal. A pesquisa foi realizada em consórcio com árvores de barueiros (Dipteryx alata Vogel), durante o período das safras 2010-2011 e 2011-2012, no estado de Goiás, Brasil, O delineamento experimental foi em blocos casualizados, com cinco repetições. As leguminosas utilizadas foram: crotalária (Crotalaria juncea); feijão de porco (Canavalia ensiformis); feijão guandu (Cajanus cajan); estilosantes campo grande (Stylosanthes macrocephala - 20% e Stylosanthes capitata - 80%) e vegetação espontânea (tratamento controle). A taxa de decomposição dos resíduos de leguminosas e vegetação espontânea não é afetada no sistema agroflorestal. A crotalária, o feijão de porco e o estilosantes apresentam-se como opções vantajosas para o acúmulo total de nutrientes. Porém, o cultivo de crotalária com manejo de palhada visando rotação para próxima safra aumenta os teores de fósforo disponível no solo e a produtividade de espigas de milho verde com valores até 24% superiores em relação à área mantida sob vegetação espontânea, além de não afetar o crescimento das árvores.

Leguminous species can improve nutrient cycling and chemical quality of Oxisols, resulting in higher productivity of intercropped crops. Thus, this research aimed to evaluate the decomposition rate and nutrient accumulation in legume stubble, as well as its contribution to soil chemical attributes, the growth of baru trees (Dipteryx alata Vogel), and yield of intercropped maize in an agroforestry system. The experiment was developed during the crop years of 2010-2011 and 2011-2012, in Goiás State, Brazil. The experimental design was a randomized block with five replicates. Leguminous species consisted of sunn hemp (Crotalaria juncea), jack bean (Canavalia ensiformis), pigeon pea (Cajanus cajan), Stylosanthes (Stylosanthes macrocephala - 20% and Stylosanthes capitata - 80%), and spontaneous vegetation (control treatment). The decomposition rates of legume and spontaneous vegetation residues remained unchanged in the agroforestry system. Sunn hemp, jack bean, and Stylosanthes plants are advantageous options for total accumulation of nutrients. However, sunn hemp grown as straw cover for next crop seasons increases the available phosphorus levels in the soil and productivity of maize cobs. With this coverage, maize productivity values were up to 24% higher than were those with maize growing on spontaneous vegetation, besides having no effect on the growth of baru trees.

ABSTRACT To understand the production cycle of a particular cultivar in a given region, it is necessary to obtain information related to its phenology and the accumulated degree days. The purpose of this study was to evaluate the phenological cycle of citrus species grafted onto two rootstocks and grown in the Low-Middle Region of the São Francisco River Basin, in particular with respect to accumulated degree days. The experiment was conducted using ‘Rubi’ and ‘Pera D-12’ oranges and ‘Page’ mandarins. Two rootstocks were used, namely ‘Cravo’ and ‘Volkameriano’ lemon species that were drip irrigated in the Campo Experimental de Bebedouro, an experimental field owned by Embrapa Semiárido. ‘Page’ mandarins with ‘Cravo’ or ‘Volkameriano’ rootstocks exhibited a subperiod (0-10) of 183.32 and 181.24 days, respectively. Meanwhile, ‘Pera D-12’ and ‘Rubi’ oranges with ‘Cravo’ rootstocks had values of 249.57 and 178.58 days, respectively, while those with ‘Volkameriano’ rootstocks had values of 226.35 and 200.41 days, respectively. The accumulated degree days were measured from the initial sprouting to harvesting, which took place when the fruits presented a soluble solids/titratable acidity ratio equal to or greater than 12. ‘Page’ mandarins required 2,720 degree days, whereas ‘Pera D-12’ and ‘Rubi’ oranges required approximately 3,390 and 2,280 degree days, respectively. Finally, ‘Pera D-12’ and ‘Rubi’ oranges with either rootstock presented cycles characterized as mid-season and precocious, respectively, while ‘Page’ mandarins had precocious cycles. | RESUMO Para definir o ciclo de produção de uma cultivar em uma determinada região são necessárias informações relacionadas à fenologia e ao acúmulo de graus-dia para a sua produção. O objetivo deste trabalho foi avaliar o ciclo fenológico de espécies cítricas, enxertadas sobre dois Porta- enxertos em função do acúmulo de graus-dias nas condições do Submédio São Francisco. O experimento foi conduzido com duas laranjeiras ‘Rubi’ e ‘Pera D-12’ e uma tangerineira ‘Page’, sobre dois porta-enxertos: limoeiros ‘Cravo’ e limoeiro ‘Volkameriano’, irrigadas por gotejamento, no Campo Experimental de Bebedouro, pertencente à Embrapa Semiárido. Para a tangerineira ‘Page’ nos porta-enxertos ‘Cravo’ e ‘Volkameriano’, o subperíodo (0-10) foi de 183,32 dias e 181,24 dias, respectivamente; para as laranjeiras ‘Pera D-12’ e ‘Rubi’, sobre o porta-enxerto ‘Cravo’, foi de 249,57 dias e 178,58 dias e, para o ‘Volkameriano’, foi de 226,35 dias e 200,41dias, respectivamente. Desde a emissão da brotação até a colheita, fase em que os frutos apresentaram valor de “ratio” igual ou superior a 12, para a tangerineira ‘Page’ foram necessários aproximadamente 2.720 graus-dias, e para as laranjeiras ‘Pera D12’ e ‘Rubi’, aproximadamente 3.390 e 2.280 graus-dias, respectivamente. As laranjeiras ‘Pera D-12’ e ‘Rubi’, enxertadas sobre os dois porta-enxertos apresentaram ciclos caracterizados como sendo de meia-estação e precoce, respectivamente, e a tangerineira ‘Page’, ciclo precoce.

To understand the production cycle of a particular cultivar in a given region, it is necessary to obtain information related to its phenology and the accumulated degree days. The purpose of this study was to evaluate the phenological cycle of citrus species grafted onto two rootstocks and grown in the Low-Middle Region of the São Francisco River Basin, in particular with respect to accumulated degree days. The experiment was conducted using ‘Rubi’ and ‘Pera D-12’ oranges and ‘Page’ mandarins. Two rootstocks were used, namely ‘Cravo’ and ‘Volkameriano’ lemon species that were drip irrigated in the Campo Experimental de Bebedouro, an experimental field owned by Embrapa Semiárido. ‘Page’ mandarins with ‘Cravo’ or ‘Volkameriano’ rootstocks exhibited a subperiod (0-10) of 183.32 and 181.24 days, respectively. Meanwhile, ‘Pera D-12’ and ‘Rubi’ oranges with ‘Cravo’ rootstocks had values of 249.57 and 178.58 days, respectively, while those with ‘Volkameriano’ rootstocks had values of 226.35 and 200.41 days, respectively. The accumulated degree days were measured from the initial sprouting to harvesting, which took place when the fruits presented a soluble solids/titratable acidity ratio equal to or greater than 12. ‘Page’ mandarins required 2,720 degree days, whereas ‘Pera D-12’ and ‘Rubi’ oranges required approximately 3,390 and 2,280 degree days, respectively. Finally, ‘Pera D-12’ and ‘Rubi’ oranges with either rootstock presented cycles characterized as mid-season and precocious, respectively, while ‘Page’ mandarins had precocious cycles.

ABSTRACT Sweet corn is an important crop because of its seeds with high total sugar and low starch contents. As common corn, this group requires an adequate amount of nitrogen to reach high yields. However, the studies on nitrogen and sweet corn are performed for ear yield instead of seed yield. As seeds are the main propagation method for this species, we proposed to evaluate the effects of nitrogen rates as side-dressing at different plant stages of a sweet corn seed production. Sweet corn seeds (variety BR 400) were sown in Latosol (Oxisol), and a 3×2+1 factorial scheme was designed with three nitrogen rates (40, 80, and 120 kg ha-1) at two plant stages (V6 and R1) plus the control (no nitrogen side-dressing). The evaluated variables were seed yield, protein content, P and Zn contents, germination, and vigor rates. We concluded that nitrogen applied at a rate of 120 kg ha-1 at V6 increases seed yield and maintains unaltered the protein content in seeds of sweet corn (BR 400 variety). Neither germination nor seed vigor increases when nitrogen rates are increased or administered at different stages of plant development. We also noted a slight decrease in P content or an increase in Zn content of seeds at low nitrogen rates; however, they are insufficient to promote changes in the physiological potential of sweet corn seeds. | RESUMO O milho doce é uma cultura importante por causa do seu tipo de sementes com índice elevado dos açúcares totais e baixo índice do amido. Como o milho comum, este necessita de quantidade adequada de nitrogênio para atingir altas produtividades, no entanto, os estudos que envolvem nitrogênio e milho doce são realizados para o rendimento das espigas e não para a produção de sementes. Como a semente é o principal método de propagação dessa espécie, foi avaliado os efeitos das doses de nitrogênio em cobertura em diferentes estádios fenológicos para produção e potencial fisiológico de sementes de milho doce. As sementes de milho doce (variedade BR 400) foram semeadas em Latossolo e um esquema fatorial de tratamento 3 × 2 + 1 foi instalado com três doses de nitrogênio 40, 80 e 120 kg ha-1 e dois estádios fenológicos (V6 e R1) mais o controle (sem nitrogênio em cobertura). Foram avaliadas a produtividade de sementes, teores de proteína, P e Zn, germinação e vigor. Como conclusão, o nitrogênio fornecido em V6 a 120 kg ha-1 aumenta a produtividade de sementes e mantém os teores de proteína inalterados. A germinação da semente e o vigor não aumentam quando as taxas de nitrogênio são acrescidas ou fornecidas em diferentes estádios fenológicos. Diminuição ligeira do teor de P ou o aumento do teor de Zn nas sementes são observados a uma dose baixa de nitrogênio entretanto não suficientes para promover alterações no potencial fisiológico das sementes do milho doce.

Sweet corn is an important crop because of its seeds with high total sugar and low starch contents. As common corn, this group requires an adequate amount of nitrogen to reach high yields. However, the studies on nitrogen and sweet corn are performed for ear yield instead of seed yield. As seeds are the main propagation method for this species, we proposed to evaluate the effects of nitrogen rates as side-dressing at different plant stages of a sweet corn seed production. Sweet corn seeds (variety BR 400) were sown in Latosol (Oxisol), and a 3×2+1 factorial scheme was designed with three nitrogen rates (40, 80, and 120 kg ha-1) at two plant stages (V6 and R1) plus the control (no nitrogen side-dressing). The evaluated variables were seed yield, protein content, P and Zn contents, germination, and vigor rates. We concluded that nitrogen applied at a rate of 120 kg ha-1 at V6 increases seed yield and maintains unaltered the protein content in seeds of sweet corn (BR 400 variety). Neither germination nor seed vigor increases when nitrogen rates are increased or administered at different stages of plant development. We also noted a slight decrease in P content or an increase in Zn content of seeds at low nitrogen rates; however, they are insufficient to promote changes in the physiological potential of sweet corn seeds.

RESUMO A madeira é a principal fonte de energia na matriz energética dos países subdesenvolvidos e nos países em desenvolvimento a participação é significativa, ocupando o quarto lugar no Brasil. Sendo assim, o objetivo desse trabalho foi determinar um modelo para determinação da densidade energética de espécies arbóreas do Cerrado. As amostras foram coletadas de árvores em uma área de cerrado de 10,15 hectares. Foram coletadas amostras de tronco e galhos de 34 espécies florestais para análise imediata (cinzas, material volátil, carbono fixo) e poder calorífico superior. Dados de massa seca e massa saturada foram obtidos para a determinação da densidade básica. As espécies apresentaram valores de teor de material volátil entre 77% e 85,5%, teor de cinzas entre 0 e 1% , teor de carbono fixo entre 14% e 23% . O poder calorífico superior ficou entre 18.282 GJ/ton e 20.121 GJ/ton. Quando testadas as relações entre as variáveis da análise imediata (MV, CZ e CF), e o poder calorífico superior (PCS), foi encontrada relação significativa entre MV e CF (R2 = 0.9927), enquanto o poder calorífico superior e a densidade básica das espécies não apresentaram relação significativa. O valor médio da densidade energética para as 34 espécies foi de 12.459 Mcal.m-3. A estimativa da densidade energética da área foi de 1.378.541 Mcal/ha. O modelo proposto para o cálculo de densidade energética em função da densidade básica facilita os levantamentos energéticos de áreas a serem exploradas, pois não há necessidade da análise de poder calorífico. | ABSTRACT Wood is the main source of energy in the energy matrix of underdeveloped countries, in addition to having a significant participation in developing countries, ranking fourth in Brazil. Thus, this study aimed to determine a model for determining the energy density of forest species from the Cerrado. Samples of trunks and branches were collected from 34 forest species in an area of 10.15 ha located in the Cerrado region aiming for immediate analysis, i.e. the contents of ashes (ASH), volatile matter (VM), fixed carbon (FC), and higher calorific value (HCV). Data from dry and saturated mass were obtained in order to determine the basic density. The species presented values of VM ranging from 77 to 85.5%, ASH from 0 to 1%, FC from 14 to 23%, and HCV ranging from 18,282 to 20,121 GJ ton-1. A significant relationship was found between VM and FC (R2 = 0.9927) whereas no significant values were found between HCV and basic density. The average value of energy density considering the 34 species was 12,459 Mcal m-3. The estimated energy density of the area was 1,378,541 Mcal ha-1. The proposed model for calculating the energy density as a function of basic density favors energy surveys of areas to be explored since there is no need for calorific value analysis.

Wood is the main source of energy in the energy matrix of underdeveloped countries, in addition to having a significant participation in developing countries, ranking fourth in Brazil. Thus, this study aimed to determine a model for determining the energy density of forest species from the Cerrado. Samples of trunks and branches were collected from 34 forest species in an area of 10.15 ha located in the Cerrado region aiming for immediate analysis, i.e. the contents of ashes (ASH), volatile matter (VM), fixed carbon (FC), and higher calorific value (HCV). Data from dry and saturated mass were obtained in order to determine the basic density. The species presented values of VM ranging from 77 to 85.5%, ASH from 0 to 1%, FC from 14 to 23%, and HCV ranging from 18,282 to 20,121 GJ ton-1. A significant relationship was found between VM and FC (R2 = 0.9927) whereas no significant values were found between HCV and basic density. The average value of energy density considering the 34 species was 12,459 Mcal m-3. The estimated energy density of the area was 1,378,541 Mcal ha-1. The proposed model for calculating the energy density as a function of basic density favors energy surveys of areas to be explored since there is no need for calorific value analysis.

ABSTRACT The tropical dry areas have suffered the most severe anthropic pressures. This factor motivates studies aimed at characterizing and monitoring the soil quality to determine the management measures to apply and to suggest appropriate recovery procedures. The objective of this study was to evaluate the enzymatic activity of acid and alkaline phosphatases, urea and arylsulfatase in the superficial layers of soils in areas under different stages of forest regeneration, in Floresta-PE City.. Soil sampling was conducted at 0-5, 5-15 and 15-30 cm layer in the following areas: C-18 (vegetation regeneration for 18 years), P-13 (13 years), L-12 (12 years), C-9 (9 years), C-7 (7 years) and G-4 (4 years). The analytical methods used in the study were based on the incubation of the soil samples with a buffered solution of substrate specific for each enzyme. The methods were based on colorimetric determinations. The activity of acid and alkaline phosphatase and urease represented sensitive measures for detecting changes in soil quality at various stages of regeneration in tropical dry forests. The area with the longest duration of forest regeneration (C-18) showed higher enzyme activities. The soil enzymatic activities respond to different stages and management of forest regeneration in Brazilian tropical dry areas, namely Caatinga. The acid and alkaline phosphatase, arylsulfatase and urease increased with time of regeneration. | RESUMO As áreas tropicais secas são as que sofrem as mais severas pressões antrópicas. Este fator motiva estudos que objetivam caracterizar e monitorar a qualidade do solo visando determinar estratégias de manejo para os produtores. O objetivou-se avaliar a atividade enzimática das enzimas fosfatases ácida e alcalina, uréase e arilsulfatase nas camadas superficiais de solos em áreas sob diferentes estágios de regeneração florestal, no município de Floresta-PE. Amostras de solos foram coletadas nas camadas 0-5, 5-15 e 15-30 cm nas áreas C-18 (regeneração por 18 anos), P-13 (13 anos), L-12 (12 anos), C-9 (9 anos), C-7 (7 anos) e G-4(4 anos). Os métodos analíticos usados neste estudo foram baseados na incubação das amostras de solo com soluções tamponadas de substratos específicos de cada enzima. Os métodos foram baseados em determinações colorimétricas. As atividades das fosfatases e uréase foram sensíveis em detectar mudanças na qualidade de solos com vários estágios de regeneração em áreas secas tropicais. As áreas com maior tempo de regeneração (C-18) mostraram maiores atividades enzimáticas. As atividades enzimáticas do solo respondem a diferentes estágios e manejo de regeneração florestal nas áreas secas tropicais brasileiras, nomeadamente Caatinga. A fosfatase ácida e alcalina, arilsulfatase e urease aumentaram com o tempo de regeneração.

The tropical dry areas have suffered the most severe anthropic pressures. This factor motivates studies aimed at characterizing and monitoring the soil quality to determine the management measures to apply and to suggest appropriate recovery procedures. The objective of this study was to evaluate the enzymatic activity of acid and alkaline phosphatases, urea and arylsulfatase in the superficial layers of soils in areas under different stages of forest regeneration, in Floresta-PE City.. Soil sampling was conducted at 0-5, 5-15 and 15-30 cm layer in the following areas: C-18 (vegetation regeneration for 18 years), P-13 (13 years), L-12 (12 years), C-9 (9 years), C-7 (7 years) and G-4 (4 years). The analytical methods used in the study were based on the incubation of the soil samples with a buffered solution of substrate specific for each enzyme. The methods were based on colorimetric determinations. The activity of acid and alkaline phosphatase and urease represented sensitive measures for detecting changes in soil quality at various stages of regeneration in tropical dry forests. The area with the longest duration of forest regeneration (C-18) showed higher enzyme activities. The soil enzymatic activities respond to different stages and management of forest regeneration in Brazilian tropical dry areas, namely Caatinga. The acid and alkaline phosphatase, arylsulfatase and urease increased with time of regeneration.

ABSTRACT Myroxylon balsamum is a valuable tropical tree; besides the good quality of its timber it also provides valuable nontimber forest products: balsam and resin. High deforestation rates in the area of distribution and the unregulated extraction of its resin and wood have led M. balsamum to be endangered or threatened. Its regeneration through seeds has been poorly studied, and there are no reports of germination and plasticity under controlled conditions. We evaluated the effect of scarification (longitudinal cut of the fruit and embryo fully exposed) and environmental factors (different levels of light intensities and changing temperatures) on seed germination and the development of seedlings. From the aforementioned, M. balsamum seeds are orthodox and show physical dormancy. In view of these characteristics, M. balsamum can be managed efficiently to initiate conservation programs and restoration in degraded land. | RESUMO Myroxylon balsamum é uma valiosa árvore tropical, com madeira de boa qualidade e que também fornece produtos não madeiráveis, como bálsamo e resina. As elevadas taxas de desmatamento em sua distribuição natural e a extração não regulamentada de sua resina e madeira têm levado esta espécie à ameaça de extinção. A regeneração desta espécie tem sido pouco estudada, não havendo registros sobre a germinação e plasticidade de sua semente sob condições controladas. Neste trabalho avaliou-se o efeito da escarificação (corte longitudinal do fruto, exposição do embrião, testemunha não escarificada) e de fatores ambientais (diferentes níveis de intensidades luminosas e de regimes de temperatura) na capacidade germinativa da semente e no desenvolvimento das plântulas. A semente de M. balsamum é ortodoxa e os tratamentos de escarificação promoveram sua germinação. Pode haver uma latência física. A informação derivada deste trabalho pode apoiar programas de conservação e de restauração com M. balsamum.

Myroxylon balsamum is a valuable tropical tree; besides the good quality of its timber it also provides valuable nontimber forest products: balsam and resin. High deforestation rates in the area of distribution and the unregulated extraction of its resin and wood have led M. balsamum to be endangered or threatened. Its regeneration through seeds has been poorly studied, and there are no reports of germination and plasticity under controlled conditions. We evaluated the effect of scarification (longitudinal cut of the fruit and embryo fully exposed) and environmental factors (different levels of light intensities and changing temperatures) on seed germination and the development of seedlings. From the aforementioned, M. balsamum seeds are orthodox and show physical dormancy. In view of these characteristics, M. balsamum can be managed efficiently to initiate conservation programs and restoration in degraded land.

ABSTRACT Safflower crops is usually intended for production of seeds to oil extraction. The objective of this work was to evaluate the chlorophyll index, biometric characteristics and water use efficiency of safflower plants grown under different nitrogen and potassium rates and controlled soil water tension. The experiment was conducted in a greenhouse, in pots containing 8 dm3 of a Oxisol. A complete randomized block experimental design in a 5x5 factorial arrangement was used, with four replications, consisting of five nitrogen rates (0, 60, 120, 180 and 240 mg dm-3) and five potassium rates (0, 50, 100, 150 and 200 mg dm-3). The safflower number of leaves, stem diameter, chlorophyll index, number of capitula, shoot, root and total dry weights, water consumption and water use efficiency were evaluated. Data were subjected to analysis of variance (F test) at 5% of probability and to polynomial regression. The nitrogen and potassium fertilization, as independent factors, affected the safflower plants. The chlorophyll index, biometric characteristics and water use efficiency of safflower showed better responses under nitrogen rates of 82 to 168 mg dm-3. The responses of chlorophyll index, biometric characteristics and water use efficiency of safflower increased 10 to 60% with potassium fertilization. | RESUMO O cártamo destina-se à produção de grãos para a obtenção de óleo vegetal. Objetivou-se avaliar o índice de clorofila, as características biométricas e a eficiência no uso da água de plantas de cártamo sob doses de nitrogênio e potássio. O experimento foi conduzido em casa de vegetação, em vasos contendo 8 dm3 de um Latossolo Vermelho. O delineamento experimental foi blocos casualizados, com esquema fatorial 5x5 correspondente a cinco doses de nitrogênio (0, 60, 120, 180 e 240 mg dm-3) e cinco doses de potássio (0, 50, 100, 150 e 200 mg dm-3), com quatro repetições. Avaliou-se o número de folhas, diâmetro de caule, índice de clorofila, número de capítulos, massa seca da parte aérea, massa seca de raízes, massa seca total, consumo de água e eficiência no uso da água. Os dados foram submetidos a 5% de probabilidade de erro a análise de variância pelo teste F e regressão polinomial. O índice de clorofila, as características biométricas e a eficiência no uso da água das plantas de cártamo apresentaram melhores respostas nas doses de nitrogênio entre 82 a 168 mg dm-3. A adubação potássica nas plantas de cártamo proporcionou respostas crescentes com incrementos de 10 a 60% para o índice de clorofila, nas características biométricas e na eficiência de uso da água. As respostas a adubação com nitrogênio e potássio no cártamo ocorrem com efeito isolado.

Safflower crops is usually intended for production of seeds to oil extraction. The objective of this work was to evaluate the chlorophyll index, biometric characteristics and water use efficiency of safflower plants grown under different nitrogen and potassium rates and controlled soil water tension. The experiment was conducted in a greenhouse, in pots containing 8 dm3 of a Oxisol. A complete randomized block experimental design in a 5x5 factorial arrangement was used, with four replications, consisting of five nitrogen rates (0, 60, 120, 180 and 240 mg dm-3) and five potassium rates (0, 50, 100, 150 and 200 mg dm-3). The safflower number of leaves, stem diameter, chlorophyll index, number of capitula, shoot, root and total dry weights, water consumption and water use efficiency were evaluated. Data were subjected to analysis of variance (F test) at 5% of probability and to polynomial regression. The nitrogen and potassium fertilization, as independent factors, affected the safflower plants. The chlorophyll index, biometric characteristics and water use efficiency of safflower showed better responses under nitrogen rates of 82 to 168 mg dm-3. The responses of chlorophyll index, biometric characteristics and water use efficiency of safflower increased 10 to 60% with potassium fertilization.

ABSTRACT The present study aimed at assessing the influence of physical properties associated with soil structure on the Srelative index. Two soil conditions under Ficus carica L. cultivation were studied (with or without liquid bovine biofertilizer in the irrigation water), in the 0-0.1 m and 0-0.3 m layers. Disturbed and undisturbed soil samples were collected from the above-mentioned layers and physical analyzes, pertinent to the study objective, were performed. The response function model was applied to verify how the soil independent physical variables influence on the Srelative index in the 0-0.1 m and 0-0.3 m layers, with 0 and 60% biofertilizer, being combined two to two. Once the response functions were known, the slopes of both functions were compared, being represented by the coefficients β11-β12 and β21-β22. This comparison enabled verifying whether there was an effect of the treatments on the response variable. In addition, the standard error of the difference between coefficients was calculated, and the Student's t-test applied. The method of multiple regression was also used to confirm the effect of the variables on the Srelative index for the 0-0.3 m layer in both treatments. Then, the variables with greater weight were selected by a backward elimination method to estimate the Srelative. The results showed that the Srelative index is strongly influenced by properties of the porous fraction, with total porosity and continuity of pores being of significant influence. Management with liquid bovine biofertilizer results in improvement in the soil structure, with effects measured by the Srelative index. | RESUMO Objetivou-se com esta pesquisa estudar a influência de atributos físicos associados à estrutura do solo no índice Srelativo. Foram contempladas duas situações de solo (sob cultivo de Ficus carica L., sem aplicação e com aplicação de biofertilizante bovino líquido na lâmina de irrigação), nas camadas de 0-0,1 m e 0-0,3 m. Foram coletadas amostras de solo com estrutura preservada e não preservada nas camadas supracitadas e realizadas análises físicas pertinentes ao objetivo do estudo. Foi aplicado o modelo de função de resposta para verificar como as variáveis físicas do solo independentes influenciam no Srelativo, nas camadas de 0-0,1 m e 0-0,3 m tratadas com 0 e 60 % do biofertilizante combinadas duas a duas. Conhecidas as funções de resposta compararam-se as inclinações de ambas as funções, representadas pelos coeficientes β11-β12 e β21-β22, para verificar se houve efeito dos tratamentos na variável resposta. Além disso, calculou-se o erro padrão da diferença entre os coeficientes e aplicou-se o teste t de Student. Também foi aplicado o método de regressão múltipla para verificar o efeito das variáveis sobre o Srelativo para a camada de 0-0,3 m em ambos os tratamentos. Em seguida, por meio do método backward elimination foram selecionadas as variáveis com maior peso para a estimativa do Srelativo. Concluiu-se que o índice Srelativo é fortemente influenciado por atributos da fração porosa, sendo a porosidade total e a continuidade de poros os de influência significativa. O manejo com biofertilizante bovino líquido resulta em melhora na estrutura do solo, com efeitos mensuráveis pelo índice Srelativo.

The present study aimed at assessing the influence of physical properties associated with soil structure on the Srelative index. Two soil conditions under Ficus carica L. cultivation were studied (with or without liquid bovine biofertilizer in the irrigation water), in the 0-0.1 m and 0-0.3 m layers. Disturbed and undisturbed soil samples were collected from the above-mentioned layers and physical analyzes, pertinent to the study objective, were performed. The response function model was applied to verify how the soil independent physical variables influence on the Srelative index in the 0-0.1 m and 0-0.3 m layers, with 0 and 60% biofertilizer, being combined two to two. Once the response functions were known, the slopes of both functions were compared, being represented by the coefficients β11-β12 and β21-β22. This comparison enabled verifying whether there was an effect of the treatments on the response variable. In addition, the standard error of the difference between coefficients was calculated, and the Student's t-test applied. The method of multiple regression was also used to confirm the effect of the variables on the Srelative index for the 0-0.3 m layer in both treatments. Then, the variables with greater weight were selected by a backward elimination method to estimate the Srelative. The results showed that the Srelative index is strongly influenced by properties of the porous fraction, with total porosity and continuity of pores being of significant influence. Management with liquid bovine biofertilizer results in improvement in the soil structure, with effects measured by the Srelative index.

ABSTRACT Considering the relevance of the reduction or replacement of fresh water supplies for irrigation, to mitigate the use of agricultural fertilizers and to improve sustainability, this study aimed to evaluate water and nutritional efficiency of treated sewage in cowpea plots. The experiment was conducted in the city of Tianguá-CE, on land belonging to the Water and Sewage Treatment Company of Ceará. It used a randomized block design for the arrangement of split plots. The plots contained two water sources (treated sewage and well water). The subplots contained four irrigation levels based on potential evapotranspiration (50%, 75%, 100%, and 125% of ETc) and the sub-subplots contained four nitrogen, phosphorous, and potassium (NPK) levels (0%, 33%, 66%, and 99% of the nutritional recommendations for cowpea cultivation). The yield variables, number of pods per plant, bean numbers per pod, and bean production, were improved with increased irrigation, regardless of the water source. Examining NPK levels in particular, yields differed depending on the water source. The use of treated domestic wastewater for bean irrigation can replace up to 100% of commercial fertilizers. | RESUMO Objetivou-se com o presente trabalho quantificar os componentes de produtividade da cultura do feijão submetida a diferentes lâminas de irrigação com água de poço e esgoto doméstico tratado em solo com diferentes níveis de adubação NPK. O experimento foi conduzido em Tianguá - CE, na área da Estação de Tratamento de Esgoto da Companhia de Água e Esgoto do Ceará. Foi utilizado o delineamento em blocos casualizados, em parcelas subsubdivididas 2 x 4 x 4, referente à duas fontes hídricas (efluente de esgoto doméstico tratado e água de poço amazonas) nas parcelas, quatro lâminas de irrigação baseadas na evapotranspiração potencial (50, 75, 100 e 125% da ETc) nas subparcelas e nas subsubparcelas quatro níveis de NPK (0, 33, 66 e 99%) da recomendação nutricional para a cultura. As variáveis analisadas, número de vagens por planta, números de grãos por vagem e produtividade de grãos aumentaram em função do incremento da lâmina de irrigação, independente da fonte hídrica. Quanto ao tratamento níveis de NPK, os resultados produtivos divergiram em função da fonte hídrica. O uso do efluente esgoto doméstico tratado na irrigação do feijoeiro pode substituir até 100% dos fertilizantes comerciais.

Considering the relevance of the reduction or replacement of fresh water supplies for irrigation, to mitigate the use of agricultural fertilizers and to improve sustainability, this study aimed to evaluate water and nutritional efficiency of treated sewage in cowpea plots. The experiment was conducted in the city of Tianguá-CE, on land belonging to the Water and Sewage Treatment Company of Ceará. It used a randomized block design for the arrangement of split plots. The plots contained two water sources (treated sewage and well water). The subplots contained four irrigation levels based on potential evapotranspiration (50%, 75%, 100%, and 125% of ETc) and the sub-subplots contained four nitrogen, phosphorous, and potassium (NPK) levels (0%, 33%, 66%, and 99% of the nutritional recommendations for cowpea cultivation). The yield variables, number of pods per plant, bean numbers per pod, and bean production, were improved with increased irrigation, regardless of the water source. Examining NPK levels in particular, yields differed depending on the water source. The use of treated domestic wastewater for bean irrigation can replace up to 100% of commercial fertilizers.