Resumo No semiárido brasileiro a disponibilidade hídrica é restrita e muitas vezes a única fonte de água disponível possui altas concentrações de sais. A hidroponia permite o uso dessas águas para a produção de diversas culturas, dentre elas as hortaliças, entretanto, a salinidade pode ocasionar distúrbios nutricionais. Diante disso, foram conduzidos dois experimentos em ambiente protegido no Departamento de Engenharia Agrícola da Universidade Federal Rural de Pernambuco, objetivando-se avaliar os efeitos da salinidade sobre a nutrição mineral da alface americana cv. Tainá em sistema hidropônico Nutrient Film Technique (NFT), utilizando águas salobras no preparo da solução nutritiva, sendo essas águas obtidas pela adição de NaCl a água de abastecimento local (0,2 dS m-1), e a reposição da lâmina evapotranspirada realizada usando a respectiva água salobra utilizada no preparo da solução no Experimento I e, com água de abastecimento local no Experimento II. Para ambos os experimentos o delineamento experimental utilizado foi o de blocos ao acaso com seis tratamentos (0,2; 1,2; 2,2; 3,2; 4,2 e 5,2 dS m-1), e quatro repetições, totalizando 24 parcelas experimentais para cada experimento. O aumento da salinidade da água utilizada no preparo da solução nutritiva, independente da estratégia de reposição da lâmina evapotranspirada, proporcionou redução nos teores foliares de fósforo e potássio e aumento nos teores de cloreto e sódio. Os teores foliares de nitrogênio, cálcio, magnésio e enxofre não foram influenciados pelo aumento da salinidade da água utilizada no preparo da solução nutritiva. | ABSTRACT Water availability in the Brazilian semiarid is restricted and often the only water source available has high salt concentrations. Hydroponics allows using these waters for production of various crops, including vegetables, however, the water salinity can cause nutritional disorders. Thus, two experiments were conducted in a greenhouse at the Department of Agricultural Engineering of the Federal Rural University of Pernambuco, to evaluate the effects of salinity on the mineral nutrition of crisphead lettuce, cultivar Taina, in a hydroponic system (Nutrient Film Technique), using brackish water in the nutrient solution, which was prepared by adding NaCl to the local water (0.2 dS m-1). A randomized blocks experimental design was used in both experiments. The treatments consisted of water of different salinity levels (0.2, 1.2, 2.2, 3.2, 4.2 and 5.2 dS m-1) with four replications, totaling 24 plots for each experiment. The water added to compensate for the water - depth loss due to evapotranspiration (WCET) was the brackish water of each treatment in Experiment I and the local water without modifications in Experiment II. The increase in the salinity of the water used for the nutrient solution preparation reduced the foliar phosphorus and potassium contents and increased the chloride and sodium contents, regardless of the WCET. Foliar nitrogen, calcium, magnesium and sulfur contents were not affected by increasing the water salinity used for the nutrient solution preparation.

Water availability in the Brazilian semiarid is restricted and often the only water source available has high salt concentrations. Hydroponics allows using these waters for production of various crops, including vegetables, however, the water salinity can cause nutritional disorders. Thus, two experiments were conducted in a greenhouse at the Department of Agricultural Engineering of the Federal Rural University of Pernambuco, to evaluate the effects of salinity on the mineral nutrition of crisphead lettuce, cultivar Taina, in a hydroponic system (Nutrient Film Technique), using brackish water in the nutrient solution, which was prepared by adding NaCl to the local water (0.2 dS m-1). A randomized blocks experimental design was used in both experiments. The treatments consisted of water of different salinity levels (0.2, 1.2, 2.2, 3.2, 4.2 and 5.2 dS m-1) with four replications, totaling 24 plots for each experiment. The water added to compensate for the water-depth loss due to evapotranspiration (WCET) was the brackish water of each treatment in Experiment I and the local water without modifications in Experiment II. The increase in the salinity of the water used for the nutrient solution preparation reduced the foliar phosphorus and potassium contents and increased the chloride and sodium contents, regardless of the WCET. Foliar nitrogen, calcium, magnesium and sulfur contents were not affected by increasing the water salinity used for the nutrient solution preparation.

ABSTRACT Studies on the use of agricultural residues as an alternative to commercial substrates have become fundamental tominimising the risk of environmental contamination resulting from inadequate disposal, as well as reducing seedling production costs. This research involved an evaluation of growth variables and quality of cucumber seedlings produced in substrates with different compositions of agricultural waste with a view to providing substitutes for commercial substrate. The experiment was based on a completely randomised design, with six treatments and ten replicates. There were five treatments with increasing proportions of moinha/decreasing proportions of carbonized rice husk (0/40, 10/30, 20/20, 30/10 and 40/0%) and fixed proportions of coconut fibre (15%), eggshell (5%), pine bark (40%), and one commercial substrate treatment as the control (Bioplant®). The variables evaluated were: electrical conductivity of the substrate, plant height, stem diameter, number of leaves, Dickson quality index (DQI) and dry matter of roots and above ground parts. Results show that alternative substrates can replace commercial substrate without impairing the quality of cucumber seedlings. However, the substrate containing 40% of moinha, 0% of rice husk, 15% of coconut fibre, 5% of eggshell and 40% of pine bark resulted in the highest values for all evaluated variables and appears to be the most promising alternative substrate for the production of cucumber seedlings. | RESUMO Estudos relacionados ao aproveitamento de resíduos agrícolas como substratos alternativos aos comerciais tornaram-se fundamentais por minimizar o risco de contaminação ambiental decorrente do descarte inadequado, além de diminuir os custos de produção de mudas. Assim, objetivou-se avaliar as variáveis de crescimento e a qualidade de mudas de pepino produzidas em substratos com diferentes composições de resíduos agrícolas, em substituição total ao substrato comercial. O experimento foi realizado no delineamento inteiramente casualizado, com seis tratamentos e dez repetições, sendo cinco tratamentos com proporções crescentes de moinha/decrescentes de casca de arroz (0/40; 10/30; 20/20; 30/10 e 40/0%) e proporções fixas de fibra de coco (15%), casca de ovo (5%) e casca de pinus (40%), e um tratamento controle com substrato comercial (Bioplant®). As variáveis avaliadas foram: condutividade elétrica do substrato, altura da planta, diâmetro do colo, número de folhas, Índice de Qualidade de Dickson (IQD) e massas secas da raiz e da parte aérea. Os substratos alternativos podem substituir o substrato comercial, sem que haja prejuízos à qualidade de mudas de pepino. Entretanto, o substrato contendo 40% de moinha, 0% de casca de arroz, 15% de fibra de coco, 5% de casca de ovo e 40% de casca de pinus proporciona os maiores valores para todas as variáveis avaliadas, sendo o mais indicado na produção de mudas de pepino.

Studies on the use of agricultural residues as an alternative to commercial substrates have become fundamental tominimising the risk of environmental contamination resulting from inadequate disposal, as well as reducing seedling production costs. This research involved an evaluation of growth variables and quality of cucumber seedlings produced in substrates with different compositions of agricultural waste with a view to providing substitutes for commercial substrate. The experiment was based on a completely randomised design, with six treatments and ten replicates. There were five treatments with increasing proportions of moinha/decreasing proportions of carbonized rice husk (0/40, 10/30, 20/20, 30/10 and 40/0%) and fixed proportions of coconut fibre (15%), eggshell (5%), pine bark (40%), and one commercial substrate treatment as the control (Bioplant®). The variables evaluated were: electrical conductivity of the substrate, plant height, stem diameter, number of leaves, Dickson quality index (DQI) and dry matter of roots and above ground parts. Results show that alternative substrates can replace commercial substrate without impairing the quality of cucumber seedlings. However, the substrate containing 40% of moinha, 0% of rice husk, 15% of coconut fibre, 5% of eggshell and 40% of pine bark resulted in the highest values for all evaluated variables and appears to be the most promising alternative substrate for the production of cucumber seedlings.

ABSTRACT New hybrid onions that are more productive are currently being cultivated. Information on growth and nutrient accumulation must thus be updated to assist in the refinement of existing recommendations, enabling the better exploitation of the productive potential of these new genotypes. We determined the growth of plants and the accumulation and export of nutrients of the short-day onion ‘Soberana’ established by direct seeding. The experimental design was a randomized block with four replicates and the treatments were evaluation times. Leaf number, tissue dry weight, nutrient accumulation, and the maximum daily rate of accumulation were evaluated throughout the growing cycle. The order of nutrient accumulation was (g plant-1) K (0.72) > Ca (0.38) > N (0.32) > S (0.14) > P (0.08) > Mg (0.06) and (mg plant-1) Fe (2.26) > Mn (1.43) > Cu (0.93) > Zn (0.91) > B (0.85). Macronutrient demand was highest between 61 and 148 days after sowing (DAS), and micronutrient demand was highest between 70 and 148 DAS. | RESUMO Novos híbridos de cebola mais produtivos estão sendo cultivados atualmente. Assim, informações sobre o crescimento e absorção de nutrientes devem ser atualizadas para auxiliar no refinamento das recomendações existentes, possibilitando melhor explorar o potencial produtivo desses novos genótipos. Objetivou-se com o trabalho determinar o crescimento, acúmulo e exportação de nutrientes do híbrido de cebola Soberana no sistema de semeadura direta. O delineamento experimental foi o de blocos casualizados, com quatro repetições, onde os tratamentos foram épocas de avaliação. Avaliou-se o número de folhas, massa seca, acúmulo de nutrientes e a taxa máxima de acumulo diário. A sequência de acúmulo de nutrientes foi (g planta-1): K (0,72) > Ca (0,38) > N (0,32) > S (0,14) > P (0,08) > Mg (0,06) e (mg planta-1) Fe (2,26) > Mn (1,43) > Cu (0,93) > Zn (0,91) > B (0,85). A exigência máxima dos macronutrientes ocorreu entre 61 e 148 dias após a semeadura (DAS) e dos micronutrientes entre 70 e 148 DAS.

New hybrid onions that are more productive are currently being cultivated. Information on growth and nutrient accumulation must thus be updated to assist in the refinement of existing recommendations, enabling the better exploitation of the productive potential of these new genotypes. We determined the growth of plants and the accumulation and export of nutrients of the short-day onion ‘Soberana’ established by direct seeding. The experimental design was a randomized block with four replicates and the treatments were evaluation times. Leaf number, tissue dry weight, nutrient accumulation, and the maximum daily rate of accumulation were evaluated throughout the growing cycle. The order of nutrient accumulation was (g plant-1) K (0.72) > Ca (0.38) > N (0.32) > S (0.14) > P (0.08) > Mg (0.06) and (mg plant-1) Fe (2.26) > Mn (1.43) > Cu (0.93) > Zn (0.91) > B (0.85). Macronutrient demand was highest between 61 and 148 days after sowing (DAS), and micronutrient demand was highest between 70 and 148 DAS.