ABSTRACT One of the major ecosystem services delivered to agriculture worldwide is the reduction of pests by natural enemies. However, the landscape composition affects multiple dimensions of pest control, and non-crop habitat surrounding farm fields shows variable responses across geographies. Here, crop damage and pest abundance were compared between local farms with two antagonistic land cover and land use aspects (1- High conservation, landscape with high structural complexity; 2- High degradation, landscapes with low complexity). The field data were collected at experimental guava orchards in the Cariri Paraibano, one of the driest regions in the Brazilian Caatinga. The results show that damage caused by orthopterans and their abundance was significantly smaller in the landscape with high structural complexity. Therefore, the results support the hypothesis that crop damage and pest abundance are smaller in landscapes with high structural complexity. Additionally, the results are very important for the dryland regions as they provide information about the relationship between landscape structure and crop damage plus pest abundance in a regional gap. As drylands are critically endangered in all American continents, sustainable agricultural landscapes with the application of natural cover restoration can help drylands to achieve sustainable development.

ABSTRACT Cordia oncocalyx Allemão Baill., widely known as “pau-branco”, is a native species from the Caatinga (Brazilian Savannah) and has socioeconomic and environmental potential; however, there are few silvicultural studies on this species. Therefore, this paper aimed to analyze and compare the biometric characteristics of diaspores and seeds through manual biometrics and by digital image processing, and to evaluate the in vitro and ex vitro germination of C. oncocalyx. In the biometrics evaluation, three hundred diaspores and three hundred seeds were used, applying manual and digital biometrics. Subsequently, ex vitro emergence was determined, testing mechanical scarification (in different regions of the diaspore) and chemical scarification (immersion in sulfuric acid for 90 min and 180 min). Finally, in vitro germination was tested with different compositions of Murashige & Skoog (M&S) culture medium and sucrose addition. Results showed that digital image processing is a viable and fast technique to obtain the biometric parameters of C. oncocalyx fruit and seeds. Chemical and mechanical treatments on diaspores have not influenced seed emergence (0.33%). The composition of the culture medium has influenced the germination percentage, and the maximum value of 96% % was obtained with 6 g/L of sucrose and 0.90 g/L of M&S medium. Thus, the seminiferous propagation of C. oncocalyx can be performed successfully when the seeds are germinated in vitro, and the digital image processing shows the solidity and applicability aiming to evaluate the quantitative parameters of seed and fruit of this species.

ABSTRACT Cherry tomato cultivation in the semi-arid region of northeastern Brazil is limited by water scarcity, so it is common to use water sources with high concentrations of salts in this region, which have a deleterious effect on plants, which can be alleviated through management strategies, and fertilization with nitrogen stands out. This study aimed to evaluate the growth, gas exchange and production of cherry tomato under irrigation with saline water and nitrogen fertilization. The experiment was carried out in a screened environment at the CCTA/UFCG in Pombal - PB from October 2020 to February 2021, using a randomized block design, in a 5 × 5 factorial scheme, with five levels of electrical conductivities of water - ECw (0.3; 1.3; 2.3; 3.3 and 4.3 dS m−1) and five nitrogen doses - ND (50; 75; 100; 125 and 150% of the recommended dose for the crop), with three replicates. Irrigation water salinity from 0.3 dS m−1 reduced stomatal conductance, transpiration, CO2 assimilation rate and production components of cherry tomato. Nitrogen fertilization from 50% of the recommendation reduced stomatal conductance, transpiration and CO2 assimilation rate of cherry tomato. Irrigation with water of electrical conductivity from 0.3 dS m−1 associated with nitrogen dose of 150% of the recommendation intensified the effect of salt stress on dry biomass accumulation in cherry tomato.

ABSTRACT The objective of this study was to evaluate the effect of the conversion of secondary native vegetation (NV) to conventional systems (agriculture and pasture) in soil organic carbon (SOC) and carbon of fractions particulate organic matter (POM) and mineral-associated organic matter (MAOM) in the Brazilian semi-arid region. The study was carried out in the municipalities of Delmiro Gouveia, Inhapi and Pariconha, in Alagoas, Brazil. Soils were collected in the layers of 0-0.1, 0.1-0.2 and 0.2-0.3 m. The treatments analyzed were: agricultural crops with 4, 15 and 30 years and pasture with 10 years. As a reference, the secondary Caatinga was used. The results show that in soils with sandy texture (Neossolos Quartzarênico and Regolítico – Arenosols and Regosols, respectively), there were reductions in SOC levels and carbon in the compartment associated with minerals. The inverse can be observed in the clay-textured Argissolo (Acrisols), with 30 years of cultivation, in which there was an increase in SOC and C in the quantitative fractions of soil organic matter. In addition, despite the sandy texture of the Neossolo Regolítico, POM levels were increased in the pasture system in comparison to native vegetation, but it was not enough to recover the original SOC content of this system.

ABSTRACT Sodom apple is a plant species adapted to various ecosystems and has stood out for its economic and ecological importance. We evaluated the amplification profile of 23 ISSR primers and selected polymorphic loci for genetic studies of a natural population of Calotropis procera by collecting and extracting genomic DNA from 33 individuals. Genomic DNA was extracted using the sorbitol protocol and 2% CTAB and the ISSR amplification products were resolved by electrophoresis. Based on the amplification profile, the 23 primers were classified as suitable, moderate, and unsuitable. We described the quality of primers considering the total number of bands, mean bands per primer, percentage of polymorphism, Nei’s genetic diversity (expected heterozygosity – He), assuming Hardy-Weinberg equilibrium and the polymorphic information content (PIC). All ISSR primers showed an amplification profile, which generated 173 bands with an average of 7.5 loci per primer. However, only 18 out of the 23 tested primers allowed visible and high-quality amplification, which were classified as suitable and polymorphic. We also observed a mean of 0.30 and 0.24 for PIC and He estimates, respectively. The DiCA3`RG, TriAGA3`RC, and TriCGC3`RC primers were highly transferable to C. procera (they presented quality for amplification with good reproducibility), with PIC values higher than 0.40, He higher than 0.30, and polymorphism higher than 86%.

ABSTRACT Northern leaf blight caused by Exserohilum turcicum is an important disease of maize (Zea mays L.), and its severity depends more closely on growth lesions than on spot number. Here, we characterized the infection sites of E. turcicum on resistant and susceptible maize genotypes by analyzing the histology of lesions as well as the structural and biochemical mechanisms of infection. Maize leaves were inoculated with the pathogen at specific points and incubated in a microhumidity chamber. Samples were obtained to follow fungal development and host tissue lignification using light and electron microscopy, and the activity and electrophoretic patterns of peroxidases were determined. The time course of spore germination and appressorium formation was essentially the same for both genotypes; however, a delay of 12 h in fungal penetration, accompanied by host tissue lignification, was noted in the resistant genotype, as opposed to that in the susceptible one. Scanning electron microscopy revealed fungal mycelium in the xylem vessels of both genotypes; however, in the resistant genotype, pathogen colonization was restricted to mesophyll cells around the penetration point, where chlorotic flecks were produced. Meanwhile, in the susceptible genotype, following penetration and chlorotic fleck formation, the pathogen continued to grow inside the xylem vessels and profusely colonized mesophyll tissue distant from the penetration point, resulting necrotic lesion development. Electrophoretic patterns of peroxidases were similar between the two genotypes, with three isoenzymes present in all tissues. In addition, two novel isoenzymes were detected in chlorotic flecks, necrotic lesions, and green tissue around the lesions.

ABSTRACT The response of shallot plants to potassium differs substantially depending on the cultivar, organic matter, soil conditions, and weather in the cultivation area. This research aimed to determine some of the growth characteristics of a Tinombo variety of shallot following treatment with an organic fertilizer comprising manure and potassium in the area of Palu, Central Sulawesi. This research took the form of a greenhouse experiment with planting in pots arranged in a completely randomized factorial pattern. The first factor was the application of chicken manure at 0 and 10 tons.ha-1, while the second factor was the dose of KCl fertilizer: 0 kg.ha-1; 30 kg.ha-1; 60 kg.ha-1 and 90 kg K2O.ha-1. Each treatment was replicated three times. The application of potassium and manure significantly affected the accumulation of dry matter and the linear growth rate of shallot var. Tinombo. Manure applied at 10 tons.ha-1 increased the leaf area index when combined with 0 to 60 kg K2O.ha-1. However, the addition of manure increased the net assimilation rate at all doses of potassium fertilizer. The number of bulbs and harvest index were affected by the amount of manure and potassium fertilizer applied, but there was no significant interaction between these two factors. Applying manure and K2O fertilizer resulted in a significantly higher number of bulbs and a better harvest index than in those cases where the two types of fertilizer were not applied.

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 Developing fast-cooking, mineral-biofortified common bean lines represents an important innovation for breeding programs. Thus, this study was conducted to determine whether elite Mesoamerican common bean lines differ for cooking time and mineral concentration and to select fast-cooking, mineral- biofortified lines. The experiments were carried out in two growing seasons, in which 16 common bean genotypes were evaluated. Cooking time was determined using a Mattson cooker, and the minerals were analyzed by acid digestion. The resulting data were subjected to individual analysis of variance, combined analysis of variance, clustering by the Scott-Knott test, and selection index (multiplicative). There was a significant genotype × environment interaction effect for cooking time and the concentrations of potassium, iron, zinc and copper. Only the phosphorus concentration showed no genetic variability between the common bean lines. The ranking of the best common bean lines differed for all traits examined in the different environments, according to the Scott-Knott test. The use of the multiplicative selection index allows selecting superior common bean lines for all traits, namely, DF 07-11, DF 08-21, DF 08-20 and DF 08-28. These lines exhibit a very short cooking time (up to 15 min), high potassium concentration (> 12.00 g kg-1 of dry matter) and the highest mean values of micromineral concentration, and will thus be selected by the breeding program.

ABSTRACT Lima bean (Phaseolus lunatus L.) is the second most important socioeconomic species of the genus, consisting of a food alternative as green or mature beans. It is an income option for family farmers and the lack of superior varieties makes its recommendation difficult, considering the peculiar lima bean variability. Thus, aimed to select landraces of lima beans based on desirable agronomic traits, enabling their use in breeding programs and later recommendations to family farmers. Evaluation trials were carried out with 14 landraces of lima beans in the municipalities of São Domingos do Maranhão - MA, Teresina - PI, Bom Jesus - PI, and Tianguá - CE. The agronomic traits were evaluated: number of days until flowering, number of days until pod maturation, pod length, pod width, pod thickness, number of seeds per pod, 100-seed weight, and grain yield. The data were initially subjected to univariate analysis of variance to determine the genetic variability in different environments and, subsequently, to multivariate and cluster analyses. The evaluated landraces showed genetic divergence, not being grouped according to geographic origin, demonstrating the existence of similarity between germplasms of rural communities in neighboring states. The varieties Boca de Moça, Raio de Sol, and Fava Branca CE are the earliest; Boca de Moça, Rajada, and Raio de Sol presented the longest pods and largest seeds; and Boca de Moça, Rajada, and Mulatinha are the most productive. Therefore, it qualifies them for recommendation to family farmers and/or incorporation in lima bean breeding programs.