Comunicata Scientiae

Ornamental potential of species from the ferruginous Campo rupestre of the Carajás National Forest, Brazilian Amazon

2020-12-29T16:19:02-03:00

The flora of the ferruginous Campo rupestre that occur over the immense iron deposits of the Carajás National Forest is very unique, with several endemic and rare species. This vegetation is directly affected by mining activity, as a result of vegetation suppression and the profound disfigurement of habitats. The objective of this work was to identify the ornamental potential of the flora of the ferruginous Campo rupestre, as a strategy for ex situ conservation of ecosystem species. The species present in ten plots of 5 x 5 m were surveyed in different areas of the ferruginous Campo rupestre on the N1 plateau and the ornamental potential of each species was evaluated following a characterization key, considering morphology and habitat of occurrence. Subsequently, the species were compared with those already present on the market, as ornamental, based on the literature and on sites specialized in the sale of ornamental plants in Brazil. A total of 33 species with ornamental potential were found, distributed in 32 genera and 19 families. Most species showed high functionality for ornamentation and similarity with nationally consolidated ornamentals. Catasetum planiceps, Cyrtopodium andersonii, Epidendrum nocturnum, Mandevilla scabra, Norantea guianensis and Sobralia liliastrum have a consolidated ornamental market. The data collected support ex situ conservation strategies of the flora of the ferruginous Campo rupestre, such as its valorization, local commercialization and income generation for small extractivists in the region.

Methods of applying hydrogen peroxide to soursop seedlings irrigated with saline water

2020-12-29T16:18:41-03:00

The acclimatization of plants to salt stress, through the application of hydrogen peroxide, occurs due to the activation of the antioxidant defense system. In this sense, the aim of the study was to evaluate the levels of photosynthetic pigments and the photochemical efficiency of soursop seedlings under irrigation with saline water and different methods of applying hydrogen peroxide. The study was carried out in greenhouse conditions, in a 5 x 4 scheme, with five levels of electrical conductivity of irrigation water - CEa (0.6; 1.2; 1.8; 2.4 and 3.0 dS m^-1) and four methods of application of hydrogen peroxide-MA (without application of H2O2, application via seed soaking, application via leaf spray and application via seed soaking and leaf spray). The salinity of irrigation water up to 1.4 and 1.1 dS m^-1 caused an increase in the synthesis of chlorophyll b and carotenoids, respectively. Irrigation with water from 0.6 dS m^-1 reduced the synthesis of chlorophyll a and total of soursop plants. The application of 20 μm of H2O2 via seed imbibition results in an increase in the contents of chlorophyll a and b, total, maximum and variable fluorescence of soursop seedlings. Soaking the seeds with hydrogen peroxide increased the initial fluorescence of chlorophyll in plants irrigated with water 1.2 dS m^-1.

Growth and nutritional diagnosis of Rosemary plants submitted to nitrogen and sulfate fertilization

2020-12-29T16:19:22-03:00

Studies on the cultivation of medicinal plants are of relevance to the population since they are primary sources of medication. Among these plants stands out the rosemary (Rosmarinus officinalis L.) for having diverse therapeutic properties. The objective of this work was to evaluate the initial growth and nutritional status of rosemary plants grown with different co’ncentrations of nitrogen and sulfur. The treatments were distributed in a 4x2 factorial scheme with four nitrogen doses: 105, 210, 315, and 420 mg L-1 of nitrogen combined with two sulfur doses: 32 and 64 mg L-1 with seven replications totaling 56 experimental units. The seedlings were obtained through asexual propagation (cuttings), originating from parent plants. The experimental units were arranged in a completely randomized design. Growth evaluations were carried out at 120 days of cultivation, using: plant height (HT) stem diameter (DS), root dry matter mass (RDM), stem dry matter mass (SDM), mass leaf dry matter (LDM), total dry matter (TDM), shoot dry matter mass (SDMS). The data obtained were subjected to analysis of variance and depending on the level of significance in the F test, the study was carried out using the means test (Tukey 5%). The agronomic characteristics (HT), (DS), (RDM) and (MDMAP) were significant for N. Only (RDM) showed significant interaction for the doses of N and S. The dose 420 mg L-1 promoted the highest concentrations in the components leaf and stem. The lowest dose 105 mg L-1, N promoted the highest concentrations of S in the leaf and stem. The assimilation of S by the rosemary plants was dependent on the doses of N.

Stability and adaptability of sweet orange using mixed models

2020-12-29T15:06:18-03:00

Evaluations with sweet oranges are usually performed in several harvests and places to verify the differential behavior according to the environmental variations. This makes the selection by traditional statistical methodologies more and more difficult since they have limitations in the case of data unbalanced, common in citrus during the experimental phase due to the possibility of plot loss over the years. The objective of this work was to estimate the temporal stability and adaptability of sweet orange genotypes cultivated in eight crops under the edaphoclimatic conditions of Rio Branco, Acre. The experimental design used was in randomized blocks containing 55 genotypes and three replications. Four agronomic characteristics were evaluated during eight harvests. The genetic parameters were estimated using the REML/BLUP methodology. After detecting the presence of significant interaction between genotypes and environments, stability and adaptability analyzes were conducted by the methods of the harmonic mean of the genotypic values (HMGV), the relative performance of the genetic values (RPGV) and the harmonic mean of the relative performance of the genotypic values (HMRPGV). The HMRPGV can be used to select stable, adapted and productive sweet orange genotypes. The number 48, 19, 5, 14, 2, 47 and 37 sweet orange genotypes can be selected for cultivation in an environment similar to the one studied, as they simultaneously present high stability, adaptability and productivity.

Morphophysiology of the passion fruit ‘BRS Rubi do Cerrado’ irrigated with saline waters and nitrogen fertilization

2020-12-29T16:18:20-03:00

This study aimed to evaluate the gas exchanges and growth of the purple passion fruit cultivar ‘BRS Rubi do Cerrado’ as a function of the salinity levels of the irrigation water and nitrogen fertilization. The research was conducted in pots adapted as drainage lysimeters, placed within a plant nursery, using a Regolithic Neosol of sandy texture, in the municipality of Pombal-PB, Brazil. A randomized block design was used, testing five levels of electrical conductivity of irrigation water (0.3, 1.1, 1.9, 2.7, and 3.5 dS m-1) associated with four doses of nitrogen (50, 75, 100, and 125% of the recommendation). The irrigation water salinity above 0.3 dS m-1 compromised the leaf area and the relative water content of the purple passion fruit ‘BRS Rubi do Cerrado’. High doses of nitrogen enhance the deleterious effects of irrigation water salinity on stomatal conductance, transpiration, internal CO2 concentration, CO2 assimilation rate, number of leaves, stem diameter, and height of purple passion fruit plants. When waters with salinity levels of up to 1.3 dS m-1 are used, the dose of 125 mg of N kg-1 of soil is recommendation for providing increases in the CO2 assimilation rate of the purple passion fruit ‘BRS Rubi do Cerrado’ at 70 days after sowing (DAS). Water salinity increases electrolyte leakage, regardless of nitrogen doses.

Concentrations of indolebutyric acid on air-layering of guava cv. Paluma

2020-12-29T16:17:57-03:00

Nowadays, the predominant technique for the commercial propagation of guava seedlings is through cuttings, using herbaceous cuttings that need a specialized infrastructure with intermittent misting, clean water, exhausters, water filters, and fans. As an alternative to plant propagation by cuttings, this study aimed to evaluate the influence of concentrations of indolebutyric acid (IBA) on the rooting of branches of the guava cv. Paluma by air-layering. The experimental design was in randomized blocks, with four replications and 10 air layers per plot. The treatments consisted of six concentrations of IBA powder mixed with industrial talcum: 0, 1,000, 2,000, 3,000, 4,000, and 5,000 mg.kg-1. Four adult guava parents that were in the off-season period were used. For the preparation of the air layers, the stems were girdled with a 4.0 cm width, using a steel blade, by removing the bark until exposing the cambium region, followed by IBA application and wrapping of the branches with a plastic bag containing moist organic substrate. The following variables were evaluated 120 days after air-layering: percentage of rooted and callused air layers, longest root length, and root dry matter. The analysis of variance indicated no significant differences between the IBA concentrations for all variables, but the rooting percentages were high (68.6 to 92.2%) regardless of the application of the exogenous auxin.