ABSTRACT The objective of this study was to evaluate, through multivariate data analysis, the effect of exogenous application of hydrogen peroxide on the photosynthetic pigments, gas exchange and growth of soursop seedlings under salt stress. The study was conducted in a greenhouse, at Federal University of Campina Grande - Paraíba. The assay was carried out from May to October 2018. The treatments were distributed in a randomized block design, in a 5 × 5 factorial arrangement, corresponding to five levels of irrigation water electrical conductivity - ECw (0.6-control, 1.2, 1.8, 2.4, and 3.0 dS m-1) and five concentrations of hydrogen peroxide - H2O2 (0, 10, 20, 30, and 40 μM), with two plants per plot and four replicates. Irrigation water salinity from 1.2 dS m-1 negatively affected the biosynthesis of photosynthetic pigments, gas exchange and growth of soursop. Application of hydrogen peroxide at the concentration of 20 μM resulted in attenuation of salt stress effects on the biosynthesis of photosynthetic pigments, gas exchange and growth of soursop. Hydrogen peroxide concentrations above 30 μM intensified the deleterious effect of irrigation water salinity on the photosynthetic pigments, gas exchange and growth of soursop.

ABSTRACT Considering the losses of phosphorus (P) in the soil by the adsorption process and that the use of biochar seems promising from the agricultural point of view, the aim of this research was to evaluate P adsorption by the Ultisol incubated with different biochar doses through kinetic and isothermal study. The experiment was carried out with poultry litter biochar pyrolyzed at 350 °C. Ultisol was incubated with increasing biochar doses, from 0.0 to 61.95 t ha-1. After 60 days, the phosphorus adsorption rate, kinetics and adsorption isotherms were evaluated. The results showed that the soil had the highest capacity to adsorb phosphorus (1.105 mg g-1). Biochar was not a good P adsorbent; regardless of the applied doses, it released P to the equilibration solution. Langmuir model was better at describing the adsorption of P. The pseudo-second order model fitted well to the adsorption kinetics of P, showing that the adsorption is chemically controlled. These results suggest that biochar can increase the availability of P, limiting adsorption; therefore, it could be used as a fertilizer and/or soil conditioner.

ABSTRACT The storage life of ‘Alexander Lucas’ pear is limited by the occurrence of internal storage disorders during controlled atmosphere (CA). 1-Methylcyclopropene (1-MCP) can be used to delay pear ripening, however, its interaction with CA conditions is not well understood. ‘Alexander Lucas’ fruit were treated with 1-MCP at 300 nL L-1 for 24 h in air at-0.5 or 1.0 °C before being stored. Fruit were kept at-0.5 or 1.0 °C in normal air or CA (2.0 kPa O2 plus <0.7 kPa CO2). After six months of storage, superficial scald did not develop in fruit. The highest incidence of flesh browning (72.2 %) was found in air-stored fruit at-0.5 °C without 1-MCP treatment. Storage in air at 1.0 °C plus 300 nL L-1 1-MCP produced 88.8 % of healthy fruit. In contrast, 1-MCP increased the incidence of flesh and core browning under CA conditions. 1-MCP and CA maintained greener skin color and higher titratable acidity. No significant differences were found for fruit firmness, total soluble solids and ascorbic acid content between the treatments. In conclusion, the quality of ‘Alexander Lucas’ pear was best maintained during six months storage under normal air at 1.0 °C combined with 300 nL L-1 1-MCP treatment.

ABSTRACT Family farming is important for the production of food for human consumption, but it lacks resources to invest in the soil fertility of its crops. The objective of this study was to analyze whether the use of green manures increases soil fertility in terms of the nutrients N, P and K with low environmental risk for family agricultural production. An experiment was set up in the State of Mato Grosso (Brazil), in randomized complete block design, with a 6 x 3 factorial scheme, four replications, corresponding to 6 types of plants and 3 doses of phosphorus. Leguminous green manure plants were: velvet bean, Crotalaria juncea, Crotalaria ochroleuca and dwarf pigeon pea, in addition to plots with pearl millet and weedy fallow control. Rock phosphate (i.e., reactive natural phosphate) was applied as a source of phosphorus at 0, 50 and 100 kg P2O5 ha-1. The species used as green manure were cut in full bloom and the levels of N, P, K and C in plants and soil were determined. Leguminous green manure plants, after mineralization, increased the stocks of N, P and K in the soil. Crotalaria juncea was the one that reached the highest N accumulation in its constitution, being recommended in the intercropping with species with C/N ratio > 30 to minimize risks of contamination with nitrate in the soil. This work concluded that the managements with green manure plants, especially Crotalaria ochroleuca, are recommended and environmentally safe technical alternatives for family farming.

ABSTRACT Bromeliad Quesnelia quesneliana (Brongniart) L.B. Smith has been reported in the Atlantic Forest, Rainforest, Mesophilic Semideciduous Seasonal Forest, Mangroves and Restingas in the Brazilian southeastern states of Rio de Janeiro and Espírito Santo, but information about their fruit and seed morphology, and germination is limited. The aim of this study was to characterize the external morphology of fruit and seeds, germination rate and post-seminal stages of Q. quesneliana. Fruits were collected from Restinga area in the Armação dos Búzios city, Rio de Janeiro, Brazil. The width and length of fruit and seeds (external morphology) were measured, the post-seminal development of the seeds was analyzed and botanical illustrations were made. The indexes t50, uniformity of germination, mean germination time and germination speed coefficient were also calculated. Germination was assessed for 20 days by counting individuals to obtain the post-seminal stages. Ripe Q. quesneliana fruits are pyriform, reddish-brown in color, with light spots, 26 mm long and 10 mm wide, with an average of 148 seeds per fruit and wrapped in a transparent mucilage. The seeds are 2 mm long and 1 mm wide, with epigeal germination, and its seedlings are cryptocotyledonary. The seeds of this species germinate quickly and have no dormancy.

ABSTRACT Cactus seeds in seasonal dry tropical forests are subject to several stressors, such as salt stress which limits imbibition and therefore germination. Thus, this study aimed to compare germination performance of Cereus jamacaru subsp. jamacaru and Pilosocereus pachycladus subsp. pernambucoensis seeds under salinity conditions. To this end, NaCl and KCl solutions were used in the following osmotic potentials: 0.0 (control),-0.2,-0.4,-0.6,-0.8,-1.0, and-1.2 MPa. Seeds were placed to germinate at 25 °C and 12-hour photoperiod. The number of germinated seeds was counted daily for 21 days after root protrusion. The variables analyzed were: water content, germination, normal seedlings, germination speed index, and average germination time. The experimental design was completely randomized, following a 2 × 7 factorial scheme (species × osmotic potential) for each saline source. Water restriction and ionic effect caused by salts favored seed germination and vigor in both species at-0.2 and-0.4 MPa. However, from-0.8 MPa onwards, germination decreased significantly for both salts. Seeds of C. jamacaru subsp. jamacaru and P. pachycladus subsp. pernambucoensis were tolerant to salt stress since they germinated up to-0.8 MPa (NaCl) and-1.2 MPa (KCl). The latter occurred only for P. pachycladus subsp. pernambucoensis.

ABSTRACT The knowledge of genetic diversity in plant population is essential to the success of plant breeding programs. Thus, previous characterization of landraces is one of the first steps before the indication of genotypes to these plant breeding programs. This study aimed to characterize, through morphological traits, and estimate the genetic diversity in landraces of lima bean (Phaseolus lunatus L.). Genetic diversity was estimated by using multivariate methods that selected individual landraces to be indicated for farmers and consumers. According to morphological traits proposed by Biodiversity International, the genotypes UFPI-667 and UFPI- 682 showed higher dissimilarity and high potential to be used in crosses since they are genetically distant and complementary. The principal component analysis identified positive and significant phenotypic associations between variables: pod length, pod width, and grain production. According to the multivariate methods used, the landraces UFPI-666, UFPI-650, UFPI-651, UFPI-687, UFPI-658, UFPI-673, UFPI-667, and UFPI-674 are potential candidates for selection since they have relevant features for lima bean breeding, such as shorter cycles and higher grain production. This study showed that multivariate analysis can be used as an effective tool to find potential traits in lima bean and can assist the lima bean breeders in the selection of potential landraces. Accessions UFPI-667 and UFPI-682 can be indicated as genitors for breeding programs, as they are genetically distant and complementary in their characteristics.

ABSTRACT The aim of this study was to evaluate the efficiency of the porous ceramic cup extractors, associated with ion meters, for the determination of nutrients availability for bell pepper and melon crops in substrate. Substrate solution was acquired using aqueous extract 1:1.5 (v/v) and also the porous ceramic cup extractor. Electrical conductivity (EC), pH and macronutrient contents were determined for the substrate solution through analytical method. The concentrations of NO- and K+ in the solutions obtained with porous ceramic cup extractors, and the N and K contents in the diagnostic leaf for nutritional evaluation were also determined. The concentrations of NO3- and K+ using the porous ceramic cup extractors have strong correlation (r=0.96 and 0.92, respectively) with the ones obtained using the standard method, as well as a moderate correlation (r=0.65) and a strong one (r=0.71) with contents of N and K, respectively, in the melon diagnostic leaf; and a weak correlation (r=0.36 and 0.26, respectively) in the bell pepper diagnostic leaf. The use of porous ceramic cup extractors for obtaining the substrate solution and the determination of the N-NO- and K+ contents by means of specific ion meters are a fast method of evaluating nutrients availability in soilless cultures.

ABSTRACT The objective of this work was to compare soil beetle (Coleoptera) species composition between two sites on the Borborema Plateau in Northeastern Brazil. We collected 483 individuals belonging to 23 Coleoptera families and 75 species/morphospecies. On the east face of the Borborema Plateau (Areia-PB) we collected a total of 332 individuals representing 58 species/morphospecies and 21 families. On the west face (Cabaceiras-PB) we collected 151 individuals representing 24 species/morphospecies and eight families. Among the 75 total species/morphospecies collected, 51 occurred exclusively on the eastern face of the plateau and 17 occurred exclusively on the west face. Only seven morphospecies were sampled in both areas. The marked difference in beetle assemblage species composition between the west and east sides of the Borborema Plateau suggests that the positioning and climatic variations maintain and promote high levels of beetle diversity in northeastern Brazil.

ABSTRACT The objective of this study was to identify communities of arbuscular mycorrhizal fungi (AMF) in soils under pasture, silvopasture, and Cerrado forest ecosystems, and evaluate the effects of land use system, soil texture, and seasonality on the dynamics of AMF communities, in Alta Floresta D'Oeste, Rondônia, Brazil. Samples of the soil 0-20 cm layer were randomly collected in each ecosystem in July, 2010 (dry season) and January, 2011 (rainy season). Spores were extracted, counted, and identified. The spore density and density of each species of AMF were estimated. The frequency of occurrence, Shannon diversity index, and Simpson diversity index were calculated for each species. Multivariate clustering analysis was carried out, considering the number of AMF of each species. The results showed a trend of higher number of spores in the Cerrado forest ecosystem, regardless of the soil texture or season, when compared to pasture and silvopasture areas. The Glomus macrocarpum species presented 100% frequency of occurrence in the rainy season in both soil textures. The effects of texture and seasonality on the composition and diversity of AMF communities was more expressive in the Cerrado forest ecosystem. The climate, soil texture, and land use and management affected the composition and diversity of AMF species.