Potential nursing effects of Parkia platycephala Benth. (Fabaceae) in a disturbed Brazilian Savanna area undergoing restoration

We evaluated the influence of Parkia platycephala on plant assemblages under its crown and surrounding areas in a disturbed Brazilian Savanna, as well as the effects of aqueous extracts of its leaves on the germination and development of three species, under the hypothesis that P. platycephala might work as a nurse species. Eleven areas of direct (ADIs) and indirect (AIIs) influence of P. platycephala and 11 control areas (COs) were delineated. All tree and shrub species present in these areas, including seedlings, were sampled. Richness, composition and abundance of woody taxa were determined. Laboratory studies analyzed the effects of P. platycephala aqueous leaf extracts on the germination and initial development of Dipteryx alata, Enterolobium gummiferum and Magonia pubescens, which in the field exhibited different abundance levels under its crown. Regarding plant assemblages, no differences in terms of richness and abundance of woody taxa were detected among the areas. However, we recorded a gradient of species composition and abundance ranks from ADI to CO areas. The number of seedlings also differed, with higher values near P. platycephala. Soil characteristics were similar among areas, but shading, plant height and diameter differed. The aqueous leaf extract at 25% provided the best germination of M. pubescens. The extract at 75% favored the initial development of this species in terms of root length. These results indicate that the presence of P. platycephala affects the structure of neighboring plant assemblages, possibly working as a facilitator for some species in areas undergoing restoration.

Distribution of galling insects and their parasitoids on Caryocar brasiliense tree crowns

Caryocar brasiliense Camb. (Malpighiales: Caryocaraceae) is widely distributed in the Brazilian savanna and its fruits are used by humans for food, production of cosmetics, lubricants, and in the pharmaceutical industry. This plant is damaged by galling insects. Number of these galling insects and their parasitoids was recorded, in the field (galls) and in the laboratory (adults emerged from the galls), from three C. brasiliense crown heights, during three years. Numbers of adults of Eurytoma sp. (Hymenoptera: Eurytomidae), galling insect (younger attack) and Sycophila sp. (Hymenoptera: Eurytomidae) (a parasitoid of Eurytoma sp.), were greater on the apical parts of C. brasiliense tree crowns. Numbers and groups of Eurytoma sp. globoid galls (older attack) were higher in the median and basal crown parts. The numbers of Eurytoma sp. galls were higher on apical part of C. brasiliense tree crown and also of their parasitoids.

Oligochitosan Synthesized by Cunninghamella elegans, a Fungus from Caatinga (The Brazilian Savanna) Is a Better Antioxidant than Animal Chitosan

Animal chitosan (Chit-A) is gaining more acceptance in daily activities. It is used in a range of products from food supplements for weight loss to even raw materials for producing nanoparticles and hydrogel drug carriers; however, it has low antioxidant activity. Fungal oligochitosan (OChit-F) was identified as a potential substitute for Chit-A. Cunninghamella elegans is a fungus found in the Brazilian savanna (Caatinga) that produces OligoChit-F, which is a relatively poorly studied compound. In this study, 4 kDa OChit-F with a 76% deacetylation degree was extracted from C. elegans. OChit-F showed antioxidant activity similar to that of Chit-A in only one in vitro test (copper chelation) but exhibited higher activity than that of Chit-A in three other tests (reducing power, hydroxyl radical scavenging, and iron chelation). These results indicate that OChit-F is a better antioxidant than Chit-A. In addition, Chit-A significantly increased the formation of calcium oxalate crystals in vitro, particularly those of the monohydrate (COM) type; however, OChit-F had no effect on this process in vitro. In summary, OChit-F had higher antioxidant activity than Chit-A and did not induce the formation of CaOx crystals. Thus, OChit-F can be used as a Chit-A substitute in applications affected by oxidative stress.

Management of Soil Acidity and Its Relations With Soybean Productivity in Brazilian Savanna

The soils of Brazilian Savanna, naturally, present acidity problems, making correction practices fundamental to ensure production. Even with so many years since the introduction of agriculture, some soil correction practices are still misused. Thus, the objective was to evaluate soybean yield and chemical changes in a Red Oxisol in the Brazilian Savanna with the use of limestone, associated or not with gypsum, applied superficially and incorporated by harrow and moldboard plow. The experiment was conducted under field conditions, in Rio Verde-GO, cultivating soybeans in the 2015/2016 and 2016/1017 harvests. The experimental design was in randomized blocks, with four replications, with treatments arranged in a 3 × 3 factorial scheme. The first factor refers to the application of superficial limestone and incorporated by harrow and moldboard plow. The second factor was the presence or absence of limestone and/or gypsum (0 + 0; 0.875 + 0 and 0.875 + 1.75 t ha-1). Plant height, number of pods per plant, productivity, pH, Al, CTC, Ca, Mg and V were evaluated, in soil depths of 0-0.2 and 0.2-0.4 m. In the 2016/2017 harvest, the characteristics of pH, CTC, V and contents of Ca, Mg and Al were influenced by the methods of application of limestone and by its use, associated or not with gypsum. There was an increase in pH on the soil surface with the use of limestone and on the subsurface with the use of limestone and gypsum. The moldboard plow provided increases in the contents of Ca and Mg in the soil in comparison to surface application. The moldboard plow incresed in soybean yield, in the second crop, with and without association of gypsum with limestone.