RESUMO A cana-de-açúcar é uma das culturas que mais sofrem com a escassez hídrica e, para minimizar esse problema, uma das alternativas é o uso eficiente da água de irrigação. Objetivou-se com este trabalho avaliar os parâmetros biométricos, produtividade e qualidade tecnológica da cana-de-açúcar submetida a diferentes regimes de deficit hídrico controlado, na região do Submédio do Vale do São Francisco. O delineamento experimental utilizado foi em blocos casualizados, com 10 tratamentos e três repetições, sendo três deficits hídricos controlados (15; 30; e 45% da evapotranspiração da cultura - ETc), aplicados nas três fases de desenvolvimento da planta (Fase I - brotação e perfilhamento, Fase II - desenvolvimento e Fase III - maturação) e tratamento controle com 100% da ETc, realizados em dois ciclos de cultivo. A qualidade tecnológica da cana-de-açúcar não foi alterada em função do deficit hídrico controlado nas diferentes fases de desenvolvimento. A produtividade da cana-de-açúcar foi maior utilizando-se deficit hídrico controlado de 30% da ETc na fase de brotação e perfilhamento de desenvolvimento da cultura da cana-de-açúcar. A fim de se garantir maior eficiência do uso da água pelo sistema produtivo, recomenda-se a aplicação de uma lâmina com deficit hídrico de 15% da ETc, nas fases de maior desenvolvimento ou maturação do ciclo da cultura. | ABSTRACT Sugarcane is one of the most affected crops by water scarcity. The efficient use of the irrigation water is an alternative to minimize this problem. The objective of this work was to evaluate biometric parameters, yield, and technological quality of sugarcane plants subjected to different controlled water deficit regimes in the sub-middle São Francisco Valley, Brazil. The experiment was conducted in a randomized block design, in two crop cycles, with three replications, with ten treatments consisted of three controlled water deficits (15%, 30%, and 45% of the crop evapotranspiration - ETc), applied at three development stages of the plant - sprouting and tillering (Stage I), grand growth (Stage II), and maturation (Stage III) - and a control with 100% of the ETc throughout the entire crop cycle. The controlled water deficit did not affect the technological quality of the sugarcane in any development stage. The sugarcane yield was higher when using a controlled water deficit of 30% of ETc in the sprouting and tillering stages of the plants. The water deficit of 15% of ETc is recommended for the grand growth, or maturation stages of the sugarcane plants for a greater water use efficiency of the production system.

ABSTRACT Biochar is a solid material formed during biomass thermochemical decomposition processes. This organic compound has particular properties that may cause effects on soils depending on its feedstock and processing conditions. Thus, the characteristics and purpose of use of this material must be recognized prior to its use. Two types of biochar, derived from different wood sources, were compared, one from caatinga biome species and another from cashew trees. Two species from caatinga biome were used, jurema-preta (Mimosa tenuiflora Willd. Poir.), and marmeleiro (Croton sonderianus Müll. Arg.). This study aimed to identify the best biochar material regionally available to increase water-holding capacity in the soil, based on laboratory tests and microstructural porosity evaluation. Biochar from Caatinga wood demonstrated an improved water-holding capacity if compared to cashew wood biochar. The particle diameters of 2 and 4 mm showed the highest levels, which were 2,268 g.g-1 for caatinga wood and 0.574 g.g-1 for cashew wood biochars, respectively. While the smaller quantities of macropores and a larger number of micropores (smaller radius) could explain the higher water-holding capacity for biochar from caatinga wood, the thick lignified cell walls of biochar from cashew wood support the idea of a hydrophobic effect contributing to water lower holding capacity. | RESUMO Biocarvão é o material sólido formado durante a decomposição termoquímica da biomassa. Suas propriedades e efeitos no solo variam amplamente com o material de origem e condições de precessamento. Desta forma, é reconhecida a importância de sua caracterização e desempenho para o que se propõe, antes do uso. Foram comparados dois tipos de biochar, de acordo com o material de origem, espécies do bioma Caatinga, Jurema-Preta (Mimosa tenuiflora (Willd.) Poir. associada com Marmeleiro (Croton sonderianus Müll.) Arg. e lenha de cajueiro (Annacardium occidentale L.). O objetivo deste estudo foi identificar biocarvão com melhor desempenho de promover o aumento da capacidade de retenção de água no solo, com base em evidências de laboratório e avaliação de porosidade microestructural. O biocarvão oriundo das espécies da Caatinga demonstrou maior capacidade de retenção de água quando comparado com o biocarvão de lenha de cajueiro, para todos os diâmetros avaliados. Com relação ao tamanho de partículas, níveis maiores de retenção de água foram observados aos 2 mm e 4 mm, 2,268 g g-1 para o biocarvão de madeira das espécies da Caatinga e 0,574 g g-1 para o biocarvão de madeira de cajueiro, respectivamente. Menores quantidades de macroporos e maior número de microporos (raio menor) foram observados no biocarvão de madeira das espécies da Caatinga, provavelmente relacionado à mais alta capacidade de retenção de água, enquanto densamente lignificadas, as paredes celulares de madeira de cajueiro, sustenta a ideia de que um efeito hidrofóbico pode contribuir para sua menor capacidade de retenção hídrica.

ABSTRACT Drip irrigation with diluted sanitary landfill leachate favors the development of grasses on the landfill surface, however, the clogging of emitters of the irrigation systems is the major obstacle for this practice. The objective of this study was to select empirical models of the Christiansen's uniformity coefficient, distribution uniformity coefficient, and statistical uniformity coefficient of drip irrigation sets applying sanitary landfill leachate diluted in water as a function of time of operation, and quality of the effluent. An experiment was conducted in a completely randomized experimental design with three replicates, using a split-split plot arrangement, with operating pressures (70, 140, 210, and 280 kPa) in the plots, types of drippers (G1, 1.65 L h-1; G2, 2.0 L h-1; and G3, 4.0 L h-1) in the subplots, and operating time of the drip irrigation sets (0, 20, 40, 60, 80, 100, 120, 140, and 160 hours) in the sub-subplots. Data regarding hydraulic performance and effluent quality were acquired every 20 hours during 160 hours of operation and subjected to simple and multiple regression analyses. The G3 dripper operating at pressures of 70 and 140 kPa were the combinations that best attenuated biofilm clogging. The linear regression and square root were the models that best represented the reduction in the uniformity of the effluent application as a function of the operating time of the drip irrigation sets. The linear correlations denoted that calcium contents and total coliform population rates were the characteristics of the sanitary landfill leachate that most affected the drip clogging process. | RESUMO A aplicação localizada de percolado diluído permite o desenvolvimento de gramíneas na superfície das células dos aterros sanitários, entretanto a obstrução dos emissores dos sistemas de irrigação consiste no maior obstáculo desta atividade. Objetivou-se com a realização do presente trabalho selecionar modelos empíricos do coeficiente de uniformidade de Christiansen, coeficiente de uniformidade de distribuição e coeficiente de uniformidade estatístico de unidades gotejadoras aplicando percolado diluído em função do tempo de operação e da qualidade do efluente. Para isso, montou-se um experimento em parcelas subsubdivididas. Nas parcelas tem-se as pressões de serviço (70, 140, 210 e 280 kPa), nas subparcelas os tipos de gotejadores (G1 - 1,65 L h-1; G2 - 2,0 L h-1; e 4,0 L h-1) e nas subsubparcelas os tempos de operação das unidades gotejadoras (0, 20, 40, 60, 80, 100, 120, 140 e 160 h). O delineamento experimental foi o inteiramente casualizado com três repetições. Os dados dos indicadores de desempenho hidráulico e da qualidade do efluente foram obtidos a cada 20 h, até completar 160 h de funcionamento, sendo posteriormente submetidos às análises de regressão simples e múltipla. Os resultados indicaram que o gotejador G3 operando nas pressões de serviço 70 e 140 kPa foram as combinações que melhor atenuaram o entupimento com biofilme. Os modelos de regressão linear e raiz quadrada foram os que melhor representaram a redução da uniformidade de aplicação do efluente em função do tempo de operação nas unidades gotejadoras. As relações lineares revelaram que os teores de cálcio e os níveis populacionais de coliformes totais foram as características do percolado de aterro diluído que mais interferiram no processo de obstrução dos gotejadores.

ABSTRACT The production of vegetables in communities of family farmers in semiarid regions is limited due to rudimentary cultivation practices and systems, water scarcity, and excess salts in the water and soil. Thus, the objective of this work was to evaluate the production of rocket (Eruca sativa L. cv. Folha Larga) in a low cost hydroponic system, considering strategies for the use of brackish water in the nutrient solution. The experiments were conducted in complete randomized designs, in 6×2 factorial arrangements, with five replications, using rocket plants grown in different nutrient solutions, consisting of six salinity levels (1.5, 3.0, 4.5, 6.0, 7.5, and 9.0 dS m -1) and two circulation frequencies of the nutrient solution (twice a day, at 8:00h, and 16:00h; and three times a day, at 8:00h, 12:00h, and 16:00h). In Experiment I, the nutrient solution lost by evapotranspiration was replenished with the respective brackish water used in its preparation; and in Experiment II it was replenished with public water (0.12 dS m -1). The shoot and root fresh and dry biomass of the plants and their respective dry weight proportions, and biometric variables were evaluated. Replenishing of the nutrient solution with public water resulted in lower losses in biomass and plant growth. The increases in circulation frequency of the nutrient solution did not affect the biometric variables, however, the plants prioritized shoot biomass development to the detriment of the root when using high circulation frequencies. | RESUMO A produção de hortaliças em comunidades de agricultores familiares, residentes em condições semiáridas, são limitadas por práticas e sistemas rudimentares de cultivo, escassez hídrica e problemas de salinidade. Neste sentido, o objetivo do presente trabalho foi analisar a produção de rúcula, cv. Folha larga, em sistema de hidroponia de baixo custo, adotando-se estratégias de uso da água salina no preparo e reposição da solução nutritiva evapotranspirada. Em dois experimentos, plantas de rúcula foram expostas a seis níveis de salinidade da solução nutritiva (1,5; 3,0; 4,5; 6,0; 7,5 e 9,0 dS m -1) aplicadas em duas frequências de circulação (duas vezes ao dia - às 8 e 16 horas; três vezes ao dia - às 8, 12 e 16 horas). O delineamento experimental adotado foi inteiramente casualizado, em esquema fatorial 6 x 2, com cinco repetições, sendo que, no Experimento I a reposição da solução nutritiva foi efetuada com a respectiva água salina utilizada no preparo da solução e, no Experimento II, com água de abastecimento (0,12 dS m -1). Analisou-se a fitomassa fresca e seca da planta, da parte aérea e da raiz, bem como as respectivas partições de matéria seca e variáveis biométricas. A reposição da lâmina evapotranspirada com água de abastecimento resultou em menores perdas de biomassa e no crescimento das plantas e que, o aumento da frequência de circulação não influenciou as variáveis biométricas, no entanto, sob maior frequência de circulação a planta priorizou o desenvolvimento da biomassa da parte aérea em detrimento da raiz.

RESUMO O objetivo deste trabalho foi avaliar a eficiência, fitotoxicidade e efeito residual do extrato aquoso de folhas de Prosopis juliflora (Sw.) DC. (Fabaceae) para Tetranychus bastosi Tuttle, Baker & Sales (Acari: Tetranychidae) em Jatropha curcas L. (Euphorbiaceae). Para a avaliação da eficiência de controle plantas de pinhão-manso foram infestadas com 30 fêmeas adultas do ácaro e após 12 dias, foram pulverizadas com as concentrações letais (m/v) do extrato (CL50 = 53,45% ou CL90 = 85,35%) e com água destilada (testemunha), correspondendo aos tratamentos. Decorridas 24, 48, 72 e 96 e 120 horas após a aplicação do extrato, duas folhas do terço inferior, médio e superior das plantas foram amostradas e contabilizou-se os ácaros vivos por tratamento. A avaliação do efeito residual foi feita três, 24, 48, 96, 192 e 288 horas após a pulverização. Para avaliação do efeito fitotóxico do extrato foram atribuídas notas de acordo com a intensidade dos sintomas nas plantas. Constatou-se eficiência de controle por todo período avaliado, com média de 81,67% para a CL50 e 73,05% para CL90, sem diferença significativa entre os intervalos de avaliação. O extrato apresentou baixo efeito residual sobre T. bastosi, mas ao final de 12 dias a porcentagem média de redução da oviposição do ácaro foi de 49,21% e 68,86% para a CL50 e CL90, respectivamente. As plantas não apresentaram fitotoxicidade. O extrato de algarobeira apresenta potencial para o controle alternativo de T. bastosi em pinhão-manso em razão de sua eficiência sobre a mortalidade deste ácaro, redução da oviposição de fêmeas e ausência de efeito fitotóxico nas plantas. | ABSTRACT The objective of this study was to evaluate the efficiency, phytotoxicity and residual effect of the aqueous extract of leaves of Prosopis juliflora (Sw.) DC (Fabaceae) for Tetranychus bastosi Tuttle, Baker & Sales (Acari: Tetranychidae) on Jatropha curcas L. (Euphorbiaceae). For the evaluation of the control efficiency, physic nut plants were infested with 30 adult mite females and after 12 days were sprayed with the lethal concentrations (m/v) of the extract (LC50 = 53.45% or CL90 = 85.35%) and with distilled water (control), which corresponded to the treatments. After 24, 48, 72, 96 and 120 hours after application of the extract, two leaves of the lower, middle and upper third of the plants were sampled and the live mites were counted per treatment. The evaluation of the residual effect was done three, 24, 48, 96, 192 and 288 hours after spraying. To evaluate the phytotoxic effect of the extract, scores were given according to the intensity of the symptoms in the plants. Control efficiency was verified throughout the evaluated period, with an average of 81.67% for LC50 and 73.05% for LC90, with no significant difference between the evaluation intervals. The extract had a low residual effect on T. bastosi, but at the end of 12 days the average percentage of oviposition reduction of mite was 49.21% and 68.86% for LC50 and LC90, respectively. The plants did not present phytotoxicity. P. juliflora extract presents potential for the alternative control of T. bastosi in physic nut due to its efficiency on the mortality of this mite, oviposition reduction of females and absence of phytotoxic effect in the plants.

The objective of this study was to evaluate the efficiency, phytotoxicity and residual effect of the aqueous extract of leaves of Prosopis juliflora (Sw.) DC (Fabaceae) for Tetranychus bastosi Tuttle, Baker & Sales (Acari: Tetranychidae) on Jatropha curcas L. (Euphorbiaceae). For the evaluation of the control efficiency, physic nut plants were infested with 30 adult mite females and after 12 days were sprayed with the lethal concentrations (m/v) of the extract (LC50 = 53.45% or CL90 = 85.35%) and with distilled water (control), which corresponded to the treatments. After 24, 48, 72, 96 and 120 hours after application of the extract, two leaves of the lower, middle and upper third of the plants were sampled and the live mites were counted per treatment. The evaluation of the residual effect was done three, 24, 48, 96, 192 and 288 hours after spraying. To evaluate the phytotoxic effect of the extract, scores were given according to the intensity of the symptoms in the plants. Control efficiency was verified throughout the evaluated period, with an average of 81.67% for LC50 and 73.05% for LC90, with no significant difference between the evaluation intervals. The extract had a low residual effect on T. bastosi, but at the end of 12 days the average percentage of oviposition reduction of mite was 49.21% and 68.86% for LC50 and LC90, respectively. The plants did not present phytotoxicity. P. juliflora extract presents potential for the alternative control of T. bastosi in physic nut due to its efficiency on the mortality of this mite, oviposition reduction of females and absence of phytotoxic effect in the plants.

The present study aimed to assess the variations in the parameters of the exudate pH and flooding tests to evaluate the physiological quality of soybean seeds. We subjected the lots of soybean seeds to germination, emergence, exudate pH, and flooding tests. Further, water content of the seeds, first count of germination, and emergence speed index were also determined. The exudate pH test studied the variations in the soaking period and temperature, while the flooding test assessed the variations in the amount of water and temperature at different periods of immersion. The experiment design was completely randomized. The results were presented as means and were compared using the Scott-Knott test at 5% probability. The Pearson’s correlation coefficient between the exudate pH and emergence of seedlings, and also between the flooding test result and emergence of seedlings were calculated. The results of the study indicated that the exudate pH test can be used to evaluate the physiological quality of soybean seeds after 30 min of imbibition at 20 °C. Further, the flooding test was efficient in evaluating the vigor of soybean seeds after 4 h of immersion either in 50 mL of distilled water at 25 °C or in 75 mL of distilled water at 30 °C.

The apple tree depends on cross-pollination for adequate fruiting. The objective of this study was to evaluate the rate of parasitism by Varroa destructor mites and the infection rate of Nosema sp. in hives of Apis mellifera (Linnaeus) used in pollinating services in apple orchards in the municipality of Vacaria, Rio Grande do Sul state, Brazil. The study evaluated the sanitation of beehives before, during, and after apple orchard pollination. Natural parasitism by V. destructor and the presence of Nosema sp. spores were evaluated in hives from areas of forest and canola cultivation (in the 2014/2015 harvest), and from areas of forest and eucalyptus reforestation (2015/2016 harvest). In both harvests, the average rate of parasitism in the hives by V. destructor ranged from 3.0 to 6.7%. The levels of parasitism increased during the pollination period in hives from canola-cultivated areas (2014/2015 harvest), but not in those from the forest and eucalyptus reforestation areas. Spores of Nosema sp. were observed in hives in the 2014/2015 harvest but not in the 2015/2016 harvest. The levels of natural parasitism by V. destructor in A. mellifera hives used in pollination services remained low, and was within the levels reported for the southern region of Brazil. Additionally, the levels of Nosema sp. infection in the hives was low.

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.

Cowpea (Vigna unguiculata L. Walp.) is one of the most important legumes produced in tropical and subtropical regions throughout the world, especially in the developing countries in Africa, Latin America, and Asia. It is the main source of protein, calories, dietary fiber, minerals, and vitamins for a large segment of the world population. Cowpea is also a potential functional food with a range of bioactive compounds, including phenolic compounds. This legume is grown mainly in the North and Northeast regions of Brazil, but is also consumed in other regions, and is thus important for the farmers who depend on this crop for income. This study identified and quantified phenolic compounds in the cowpea cultivar BRS Xiquexique. Such quantification reveals the functional characteristics of cowpeas, mainly as a source of antioxidants, which will be essential to add value to this food and to expand its forms of consumption. The extracts were analyzed using an HPLC model LC-20AT, equipped with a manual injector. For the HPLC analysis, standard solutions were prepared with pure phenolic acids such as gallic acid, quercetin, caffeic acid, chlorogenic acid, ferulic acid, p-coumaric acid, catechin, and epicatechin. The major phenolic compounds identified were catechin (2.07± 0.329 mg 100 g-1), epicatechin (0.48 ± 0.130 mg 100 g-1), gallic acid (67.19 ± 6.200 mg 100 g-1), ferulic acid (32.07 ± 0.753 mg 100 g-1), and chlorogenic acid (3.08 ± 0.489 mg 100 g-1). We observed that the BRS Xiquexique cultivar contains functional phenolic compounds, especially gallic acid and ferulic acid, demonstrating the antioxidant potential of cowpea.