Seaweed extracts are employed as biostimulants due to their beneficial effects on crop growth and yield. Ascophyllum nodosum seaweed extract aid to improve seedling growth and development, and decrease seedlings production costs; however, the correct concentration must be used in order to maximize the biostimulant effects. Consequently, this study aimed to analyze the effects of different concentrations of a seaweed-based (Ascophyllum nodosum) biostimulant on ornamental sunflower seed germination and seedling growth. Seeds of ornamental sunflower cv. “Sol Pleno” were sown in polyethylene trays containing commercial substrate. The treatments consisted of dairy spraying 60 mL of the solutions 0 (control), 5, 10 or 15 mL L-1 biostimulant on substrate. The experimental design was completely randomized with 4 treatments (concentrations of biostimulant) and 4 replicates (10 seeds replicate-1). The evaluated variables were percentage, index and time averages of germination, seedling height, fresh and dry mass of shoot and roots, and root system morphology (WinRhizo). The increase of the biostimulant concentration enhances seed germination and seedlings development. The concentration 15 mL L-1 biostimulant showed the best results for percentage and index of germination and the lowest mean germination time and increase plant height and fresh and dry mass of shoots in relation to the control treatment. Accordingly, 15 mL L-1 biostimulant (Ascophyllum nodosum) is recommended for ornamental sunflower “Sol Pleno” seed germination and seedlings growth.

This study aimed to evaluate the accumulation and distribution of copper (Cu) in the pioneer tree Schinus terebinthifolius R. (aroeira) and non-pioneer tree Eugenia uniflora L. (pitanga) submitted to different concentrations of copper. The plants received 40 mL of Hoagland & Arnon (1950) n. 1 nutrient solution modified with 0.00032, 0.0032, 0.032 and 0.32 mM Cu 2+ applied to the soil. We analyzed biomass, biometry and Cu contents in plants and the concentration of Cu in soil. Cu concentration in the soil contaminated with 0.32 mM Cu 2+ was higher than other treatments. Neither species showed characteristics of plant phytotoxicity. However, the two species did exhibit different physiological responses to Cu; S. terebinthifolius accumulated the metal only in roots, while E. uniflora accumulated Cu in roots and leaves. The highest Cu concentration in soil was observed in the treatment with 0.32 mM Cu 2+ . Outstanding to foliar accumulation, E. uniflora could be used for biomonitoring.

The brown seaweed Ascophyllum nodosum and seaweed-derived products have been widely used as nutrient additions, biofertilizer and biostimulant in horticultural crop systems. This study aimed to evaluate the effects of a seaweed extract obtained from whole brown algae (A nodosum) on seed germination and seedling growth of ornamental marigold (Tagetes erecta). The seeds of marigold were daily sprayed with 0 (control), 5, 10 or 15 mL L −1 commercial seaweed extract Acadian Seaplants™ (70 ml). The percentage, index and average time of seed germination, seedling height, fresh, dry mass of shoots, roots and root system morphology were evaluated. The results showed that the seaweed extract enhanced all parameters related to seed germination and seedling growth and development. The best results were obtained with 15 mL L −1 seaweed extract which increased by twofold marigold seed germination and 84.00% seedling height, and both fresh and dry shoot mass and root morphology. We suggest algal extracts of Ascophyllum nodosum should be used as natural biostimulant on marigold crop, improving seed germination and seedling development.

Sewage sludge is a residual pollutant product from the treatment of urban effluent and must be adequately processed before final disposal in order to avoid environmental contamination. The use of sewage sludge in agricultural and forestry areas can improve the physical, chemical and biological properties of soil; it can also be a source of nutrients, increasing crop productivity. Accordingly, this study aimed to evaluate the growth and development of hybrid Eucalyptus urograndis (Eucalyptus grandis x E. urophylla) seedlings cultivated in soil with different doses of sewage sludge. To accomplish this, hybrid E. urograndis seedlings were cultivated for 120 days in pots containing soil (dystrophic Red-Yellow Latosol -LVA) with different doses of sewage sludge (0, 30, 60 or 90 Mg ha-1). The experiment was carried out in a randomized complete block design consisting of four treatments, three replications with four plants per replication, totaling 48 plants. Biometric, biomass and physiological variables (chlorophyll, gaseous exchange, stomatal conductance and transpiration); in addition to macro- and micronutrient contents in leaves and soils of each treatment were evaluated. The treatments with sewage sludge were statistically superior to control treatment for all variables. Therefore, we recommend the application of 60 Mg ha-1 sewage sludge for the growth of hybrid Eucalyptus urograndis seedlings. Conversely, 90 Mg ha-1 sewage sludge inhibited hybrid E. urograndis root growth. Moreover, the use of sewage sludge as organic fertilizer in tropical soils is a viable and sustainable alternative for Eucalyptus cultivation.

Uso de lodos residuales como fertilizante en eucalipto-diagnóstico de investigación Use of residual sludge as a fertilizer on eucaliptus-research diagnosis