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The excess of salts in irrigation water restricts agricultural exploitation in arid and semi-arid regions. Thus, searching for strategies of cultivation under salt stress conditions is important for the expansion of irrigated agriculture in these regions. Thus, the objective of this study was to evaluate the gas exchange and growth rates of naturally colored-fiber cotton genotypes irrigated with saline water and under exogenous foliar application of hydrogen peroxide concentrations. The experiment was carried out under greenhouse conditions, in Campina Grande - PB, using the randomized block experimental design and 4 × 3 × 2 factorial arrangement, with four concentrations of hydrogen peroxide - H2O2 (0, 25, 50, and 75 µM), three colored-fiber cotton genotypes - CG (BRS Rubi; BRS Topázio; BRS Verde) and two levels of electrical conductivity of water - ECw (0.8 and 5.3 dS m-1), with three replicates. Irrigation using water with electrical conductivity of 5.3 dS m-1 associated with foliar application of 50 µM of hydrogen peroxide favors gas exchange and growth rates of BRS Rubi cotton, at 60 days after sowing. Salinity of 5.3 dS m-1 associated with foliar applications of 50 µM of hydrogen peroxide increased the percentage of cell damage and the internal CO2 concentration, but reduced the stomatal conductance, transpiration, CO2 assimilation rate, and growth rates of BRS Topázio cotton. RESUMO O excesso de sais na água de irrigação restringe a exploração agrícola em regiões áridas e semiáridas. Assim, a busca por estratégias de cultivo sob condições de estresse salino é importante para expansão da agricultura irrigada nestas regiões. Assim, objetivou-se com a pesquisa, avaliar as trocas gasosas e as taxas de crescimento de genótipos de algodoeiro de fibra naturalmente colorida irrigados com águas salinas e sob aplicação exógena foliar de concentrações de peróxido de hidrogênio. A pesquisa foi desenvolvida em condições de casa de vegetação, em Campina Grande – PB, utilizando o delineamento experimental de blocos casualizados e arranjo fatorial 4 × 3 × 2, sendo quatro concentrações de peróxido de hidrogênio – H2O2 (0; 25; 50 e 75 µM), três genótipos de algodoeiro de fibra colorida - GA (BRS Rubi; BRS Topázio e BRS Verde) e dois níveis de condutividade elétrica da água - CEa (0,8 e 5,3 dS m-1) e com três repetições. A irrigação com água de condutividade elétrica de 5,3 dS m-1 associada a aplicação foliar de 50 µM de peróxido de hidrogênio favorece as trocas gasosas e as taxas de crescimento do algodoeiro BRS Rubi, aos 60 dias após a semeadura. A salinidade de 5,3 dS m-1 associado a aplicações foliares de 50 µM de peróxido de hidrogênio aumenta a porcentagem dano celular e a concentração interna de CO2, no entanto reduz a condutância estomática, transpiração, taxa de assimilação de CO2 e as taxas de crescimento do algodoeiro BRS Topázio.

Social wasps play an important role in controlling agricultural pests. The present study aimed to investigate the differences in abundance, species richness and composition of social wasps (Vespidae: Polistinae) between a Cerrado legal reserve, edge and agricultural matrix in an agricultural farm in Mato Grosso, Brazil. We delimited three transects and used Malaise traps which remained active for 48 hours, and were distributed equidistant over five distances from the edge to the legal reserve and agricultural matrix. In total, we collected 618 individuals and 31 species of social wasps. Our results showed that social wasp abundance was similar between the legal reserve and agricultural matrix during three stages and species richness only non-cropping stage. A similar pattern was observed for composition similarity, which presented a lower value between the legal reserve and agricultural matrix during the non-cropping stage. Our results indicate that although monoculture areas can offer food resources and be attractive to social wasps during the active cropping stages, these areas cannot host and conserve the diversity of social wasps. Legal reserve areas, for maintaining the diversity and ecosystem services provided by social wasps.

The genus Ctenomys has been widely used in karyotype evolution studies due to the variation in their diploid numbers. Ctenomys minutus is characterized by intraspecific variation in diploid number (2 n = 42, 46, 48, and 50), which makes it an interesting model to investigate genomic rearrangements mechanisms that could lead to different cytotypes in this species. Thereupon, it has been already shown that DNA methylation may participate in chromosome structure. Therefore, we aimed to investigate whether telomeres and global DNA methylation had a role in the genome rearrangements that led to this variation in C. minutus. We also realized an analysis for the presence of intrachromosomal telomeric repeats (ITRs) by fluorescence in situ hybridization. Our study demonstrated that neither telomere length nor DNA methylation had significant differences among the cytotypes. However, if only females were considered, there were significant differences for telomere length and methylation. Young individuals, regardless of their cytotypes, had the most methylated DNA. Regarding the ITRs, we found a signal on chromosome 1 in 2 n = 50b. No evidence was found that telomere length or methylation could have influenced chromosomal rearrangements, although new cytotypes seem to have emerged within the distribution of parental cytotypes by the accumulation of different chromosomal rearrangements.

The increasing demands concerning renewable energy have required ever-bigger projects, as seen with wind turbine cases; in these large projects, the surface contact presents high load and wear resistance requirements. The cooling and lubrication methods in machining are highlighted due to the reduction of costs and environmental impacts. In functional hardened surfaces, it is critical to understand the integrity aspects once they significantly affect the durability of the component. This work clarifies, how the machining parameters of feed, depth of cut, velocity of cut, minimum quantity of lubrication, and abundant cooling affected the machined surface in a large component, with a discussion about microstructural altered layer, residual stresses, and Sa, Sq, and Sz statistical parameters. The results indicated that the minimum quantity lubrication and abundant cooling produced highly compressive circumferential residual stresses. Both methods produced surfaces free of significant microstructure altered layers. The altered surface layer was very thin when detected, with a thickness of up to 2.35 µm. On optimal conditions, the minimum quantity lubrication, in relation to abundant cooling, presented residual stresses 37% higher, a thickness of altered layer 74% lower, and Sa and Sz roughness, respectively, 47% and 11% lower and Sz 12% higher.

This study was carried out to evaluate the postharvest quality of processing tomato fruits, submitted to irrigation depths and periods of suspension of irrigation before harvest, irrigated by subsurface drip in Cerrado areas in the southern region of Goiás State, Brazil, in 2015 and 2016. The experiments were established under a randomized block design, with four replicates arranged in a split plots scheme. In the plots, five irrigation depths were evaluated (50, 75, 100, 125 and 150% of the crop evapotranspiration) and, in the subplots, five periods of suspension of irrigation (0, 7, 14, 21 and 28 days before harvest) were assessed. After harvesting, which occurred at 125 days after transplanting the seedlings, the average fruit mass, fruit shape (longitudinal and transversal diameter), total soluble solids content, titratable acidity, pH, firmness, pulp yield, and water productivity for pulp yield were evaluated. Irrigation deficit, with the replacement of less than 100% of crop evapotranspiration, allowed to save water but significantly reduced the size of the fruits and the production of concentrated pulp. The suspension of irrigation before harvest decreased pulp yield and fruit size. The highest water productivity for pulp yield of tomato fruits occurred under water deficit with 50% of crop evapotranspiration. Irrigation depths from 50 to 150% of crop evapotranspiration and suspension before harvest does not influence total soluble solids content, pH, and fruit firmness.

Sweet potatoes are an important staple food for human consumption. This study evaluated sweet potato yield in response to potassium fertilization using different sources and splitting. It was conducted at the Universidade Federal da Paraíba, Areia-PB. A complete randomized block experimental design was used in a 7 × 2 factorial arrangement. The fertilization was split into seven treatments (100% after planting; 100% at 30 days after planting (DAP); 100% at 60 DAP; 50% after planting and 50% at 30 DAP; 50% after planting and 50% at 60 DAP; 50% at 30 DAP and 50% 60 at DAP; 33% after planting, 33% at 30 DAP, and 33% at 60 DAP). Two fertilization sources were used, namely potassium chloride and potassium sulfate, with three replicates. Plant fresh mass, mass of marketable roots, production of marketable roots per plant, leaf K concentration, total and marketable root yields were evaluated. Chloride and sulfate potassium efficiently increased the fresh mass of the plant and the mass of marketable roots, respectively. The marketable yield of the roots (25.16 and 22.28 Mg ha-1) was higher than the national average (14.07 Mg ha-1) when K2O was supplied in the sulfate and potassium chloride sources, respectively. The leaf K concentration remained within the standard levels for the crops under chloride and potassium sulfate fertilization. Potassium sulfate application results in higher sweet potato yields. When supplied in a single application, chloride and sulfate potassium increase the total and commercial yield only when the plants are at 60 DAP.