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.

Erythrina velutina (mulungu) is an endemic species of caatinga found in Northeast Brazil. As a result of its rapid plant growth, the species may be an alternative for the recovery of degraded areas. Thus, the present study aimed to analyze the effects of irrigation with different field capacilities (FC): 20, 50 and 80% on plant growth, antioxidative enzyme activities, membrane lipid peroxidation and organic solute contents in mulungu seedlings under greenhouse conditions. The experiment was carried out at Instituto Federal Educação, Ciência e Tecnologia do Ceará (IFCE)-Campus Maracanaú, Ceará, Brazil. Under the presented experimental conditions, E. velutina plants showed higher growth variables (dry matter yield and leaf area) when submitted to daily irrigation of 50% of FC. Irrigation at 20% of FC caused a small water deficit. However, 80% of FC watering may have resulted in an excess of water. In general, despite the reduction in plant growth in plants irrigated at 20% of FC, the activities of the antioxidant enzymes did not differ substantially between treatments. In general, the lowest organic solute contents were detected in irrigations at 20 or 80% of FC.

In the semiarid region of the Brazilian Northeast, there is still the occurrence of soils with low concentrations of organic mass and nutrients. Eichhornia crassipes (water hyacinth) is recognized as one of the top ten endemic herbs in the world. However, its accumulation capacity means it can be an alternative source of nutrients. The objective of this study was to analyse the effects of macrophyte organic residue (ROM) on plant growth, antioxidative enzyme activity and membrane lipid peroxidation in leaves and roots of sunflower seedlings submitted to drought stress conditions. The experiment was conducted under greenhouse conditions at the Instituto Federal de Educação, Ciência e Tecnologia do Ceará, Maracanaú Campus, Brazil. Samples of E. crassipes were collected in the Parangaba Lagoon, Fortaleza, Ceará, Brazil. The treatments were: 1) 100% (by volume) sand; 2) sand + fertilizer (following the recommendation of 80 kg of N/ha), and 3) sand + 100% of the recommended nitrogen in macrophytes (RN). In general, the use of ROM caused better seedling growth in relation to the other treatments in all conditions studied. Increases in antioxidative enzyme activity and reductions in the deleterious effects of drought stress on plant growth were observed.

No abstract

O percolado de aterro sanitário é um líquido produzido a partir de processos físicos, químicos e biológicos aos quais os resíduos sólidos urbanos são submetidos nos aterros sanitários. Apresenta uma composição físico-química variável e pode conter altos teores de nutrientes, sendo assim empregado na fertilização de plantas. Por isso, objetivou-se avaliar o crescimento de plantas de girassol irrigadas com água de moderada salinidade e com suplementação nutricional com percolado de aterro sanitário. O experimento foi conduzido em área experimental com cobertura de nylon (sombrite), sob delineamento inteiramente casualizado em um fatorial 4 x 2, sendo [1: 100% de areia de granulometria fina - NBR 6502; 2: areia + adubo/fertilizante orgânico misto (mistura de bagaço de cana, esterco bovino, esterco de galinha, serragem de madeira e gesso agrícola) e 80 kg de N ha-1, 3: areia + percolado de aterro sanitário e 80 kg de N ha-1; e 4: areia + percolado de aterro sanitário e 160 kg de N ha-1] e duas concentrações salinas da água de irrigação [irrigação com água destilada ou solução de NaCl a 60 mM], com 10 repetições, em vasos de 12 L. Foram realizadas análises de crescimento (altura, diâmetro do coleto, número de folhas), teores relativos de clorofila e diâmetro dos capítulos. Nas condições experimentais empregadas, substrato arenoso, as concentrações de percolado de aterro sanitário utilizadas promoveram incrementos em todas as variáveis de crescimento analisadas nas plântulas de girassol, especialmente a 80 Kg N ha-1. A irrigação com solução de NaCl a 60 mM não ocasionou efeitos negativos nas variáveis de crescimento, demonstrando assim a tolerância moderada das plantas de girassol à salinidade em substrato arenoso.