Hydrogels (polyacrylamide compounds) are recommended in agriculture and forestry as soil conditioners because they are able to absorb water and increase its stocks in the soil. The aim of this study was to determine the most suitable dose of hydrogel to establish seedlings of Enterolobium contortisilliquum (Vell.) Morong under two levels of luminosity. Seedlings of Enterolobium contortisilliquum (Vell.) Morong were planted in pots, following a design of subdivided plots, consisting of two levels of luminosity in the plots: full sun and 50% luminosity, and 10 doses of hydrogel in the sub-plots: 0.0, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5 and 6.0 g L-1. Seventy-two days after the seedlings were transplanted to the pots, plant height and diameter were determined, together with the height to diameter ratio, root length and diameter, shoot and root dry weight, and the shoot to root ratio. The lowest ratios between height and stem diameter (8.50 and 8.68) occurred in the seedlings in full sun at the doses of 0 and 2 g hydrogel L-1 respectively. For shaded seedlings the lowest ratio (8.14) occurred at the dose of 3.0 g L-1, but with a lower coefficient of determination (R2 = 0.68). Shoot dry weight increased with the dose of 2 g L-1 in full sun, and 3.5 g L-1 under shaded conditions. The doses of hydrogel giving the best initial development in seedlings under evaluation were 2 g L-1 in full sun and 3.5 g L-1 in the shaded environment. Although a response by the species to the doses of hydrogel was found, the benefits of the polymer were not evident under the conditions of the present study.

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Neste trabalho avaliou-se o uso de diferentes concentrações de resíduo de suplemento animal (RSA) para a composição de substratos para o cultivo de plantas de girassol (Helianthus annuus L.) sobre o crescimento e teores de solutos orgânicos. O uso do RSA a 50% ocasionou incrementos no número de folhas, área foliar, diâmetro do coleto e teor de N-aminossolúveis das folhas, em comparação aos tratamentos areia e fertilizante comercial. Assim, o uso do RSA a 50% da RN mostrou-se eficaz, podendo tornar-se uma alternativa viável e ambientalmente vantajosa. Palavras-chave: Adubo mineral. Helianthus annuus L. Resíduo sólido industrial. RESUMOThe study evaluated the use of different concentrations of animal supplement residue (ASR) to the composition of substrates for sunflower plants (Helianthus annuus L.), on growth and organic and inorganic solutes contents. The use of 50% ASR caused increases in the number of leaves, leaf area, stalk diameter and N-aminosoluble content of leaves compared to sand and commercial fertilizer treatments. Thus, the use of ASR at 50% of the RN was effective and could become a feaseble and environmentally advantageous alternative.

Uma técnica muito utilizada para recuperação de áreas degradadas é o plantio de mudas, uma espécie que apresenta um grande potencial é o Mulungu. Além disso, na recuperação de áreas degradadas se faz necessário o uso de fertilizantes para o solo, assim a produção de fertilizantes por meio de compostagem, mostra-se uma técnica sustentável e de baixo custo. O objetivo deste trabalho foi analisar a eficiência da fertilização pelo material proveniente de compostagem seguido por vermicompostagem no cultivo de plantas de Mulungu. Realizou-se um experimento, na casa de vegetação do IFCE campus Maracanaú, utilizando diferentes substratos: 100% areia (em volume), 50% húmus comercial, 100% húmus comercial, 50% composto orgânico, 75% composto orgânico e 100% composto orgânico. As plantas foram coletadas e foram analisadas: as produções de matéria fresca e seca e a quantificação dos teores de solutos orgânicos. Verificou-se que o crescimento das plantas e a produção de solutos orgânicos estão ligados diretamente ao teor de nitrogênio no solo, de forma que a escassez de nitrogênio é um fator limitante para o adequado crescimento do Mulungu. Nas condições experimentais empregadas, verificou-se que o tratamento contendo 75% composto orgânico ocasionou o maior crescimento das plantas de Mulungu.Palavras-chave: nutrientes, nitrogênio, solutos orgânicos, matéria fresca, matéria seca.

The aim of this study was to evaluate the initial growth of sunflower seedlings under different concentrations of sanitary landfill leachate, considering the feasibility of its use as source of nutrients for agricultural production. Biometric and vigor variables were analyzed through the measurements of collar diameter, shoot height, number of leaves and shoot and root fresh and dry matters, from January to February 2015. The experimental design was completely randomized in a 5 x 4 factorial scheme: five leachate concentrations (0, 40, 60, 80 and 100 kg N ha-1) x four harvest periods (14, 21, 25 and 29 days after sowing), with five replicates each containing two plants. The data were subjected to analysis of variance and polynomial regression, and the results of the last harvest (29 DAS) were compared by Tukey test (p ≤ 0.05). The use of sanitary landfill leachate increased all analyzed variables in sunflower plants when compared to the control plants (without leachate), especially in the treatment of 100 kg N ha-1. There was no inhibitory effect of the leachate on the initial growth of sunflower seedlings under adopted experimental conditions.