AimWe aimed to evaluate the performance of native tree species in the restoration of savanna vegetation by direct seeding, to assess whether weed control and intercropping with native grasses can contribute to the success of this method and to determine whether species performance can be explained by functional traits.LocationCerrado biome, southeastern Brazil. Old fields abandoned after decades of land use as pasture or croplands, occupied by ruderal plants and invasive grasses.MethodsWe established a direct seeding experiment with ten tree species native to the cerrado (Brazilian savanna) region. We used a factorial design in five blocks, with the following factors: (a) species; (b) weed control and (c) intercropping with native grasses. We evaluated the emergence, survival and growth of plants, and through multiple regressions we sought to explain the success of the species in direct seeding based on their functional traits.ResultsEmergence and survival in the field varied widely among species but with little or no difference between treatments. Growth was compromised by weed competition in all species. Intercropping with native grasses did not decrease weed competition. We found a functional pattern associated with species performance in direct seeding, where survival in the field is positively associated with seed mass, root depth and a greater root:shoot ratio.ConclusionWeed competition impairs seedling growth more than survival, considerably delaying restoration by direct seeding. The success of this method in the savanna will depend on the use of species that are best adapted to environments where water stress is the main obstacle to overcome and have large seeds and seedlings with a large and deep root system. Characterizing underground seedling systems is essential for predicting the success of cerrado species in direct seeding.

In Brazil, most degraded areas are occupied by exotic and invasive species, which require alternatives for their management. We evaluated the allelopathic effects of Waltheria indica in the laboratory from aqueous extracts of leaves and roots on the germination of the species Lactuca sativa L. (lettuce), Urochloa brizantha (Hochst. ex A.Rich.) RDWebster (brachiaria) and Handroanthus chrysotrichus (Mart. ex DC.) Mattos (yellow Ipe). We collected adult one-year-old Waltheria indica shrubs in ecological restoration areas by direct seeding. We used two treatments with aqueous extracts of leaves and roots and a control without extract, with ten repetitions of 10 seeds per treatment, totaling 600 seeds per test species. Germination and use of tetrazolium assays to evaluate the potential respiratory activity of the roots were used. The aqueous extract of W.indica leaves affected the number of germinated seeds of all test species, while the aqueous extract of roots affected only L. sativa and H. chrysotrichus. There were no significant differences between treatments (leaf and root extracts) in species germination. The aqueous extracts of Waltheria indica leaves and roots affected germination and cellular respiration of the studied species, mainly in Lactuca sativa. The identification of W. indica allelopathic compounds may be an initial step so that in the future new bioherbicides are produced from extracts of this species, or even that its seeds can be sown together with non-sensitive native species, aiming for control of exotic species in ecological restoration projects.

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Vegetative propagation is an alternative for the production of seedlings of native tree species such as Schinus terebinthifolia that presents a high predation rate on its seeds. In order to develop vegetative propagation technology, different concentrations of indolebutyric acid (IBA) were tested in the rooting of apical and intermediate minicuttings of Schinus terebinthifolia. The 2x4 factorial experimental design involved two types of minicuttings (apical and intermediate) and four dosages of the hormone IBA (0, 1000, 2000, and 4000 mg. L-1). The percentages of survival and rooting were evaluated. The intermediate minicuttings (37% and 35%) showed significantly greater survival than the apical cuttings (22% and 9%) respectively at 30 and 60 days, regardless of the IBA concentration. Among the rooting averages at 60 days obtained in the different concentrations of IBA, the treatment of 4000 mg. L-1 generated the highest results (9% for apical and 35% for intermediate). The vegetative propagation by minicuttings of Schinus terebinthifolia demonstrated the viability of intermediate minicuttings with high rooting associated with the highest concentration of IBA.