ABSTRACT Bitter melon (Momordica charantia L.) is a plant species recommended by the Brazilian Health Regulatory Agency (Anvisa) as hypoglycemiant. The characterization of plants is an essential step in any breeding program. The objective of the present work was to organize and characterize a bitter melon germplasm collection, based on morpho-agronomic characters, to assess its genetic diversity and identify genotypes of agronomic interest. Eighty-eight genotypes were characterized for 38 descriptors. Redundant descriptors were identified through Principal Component Analysis (PCA); after their exclusions, a new PCA was carried out to verify the dispersion among the genotypes. Groups in the PCA were defined using the kmeans clustering method. The groups were studied for phenotype pattern using radar chart. Populational diversity was estimated through Shannon and Pielou indexes. Intra group diversity was estimated through analysis of similarity (anosim). The relative importance of variables for diversity was also estimated. Seventeen variables were redundant. The genotypes were grouped into 5 groups. Groups G1 and G5 were antagonist regarding fruit and seed productions and fruit, leaf, and seed sizes. A trend of decrease in fruit, leaf, and seed sizes was found in groups from G1 to G5. The diversity was high. Intra group diversity was high among small fruit genotypes, and low for medium-sized fruit genotypes. The variable number of male flowers (NMFL) was identified as that presented the greatest contribution to estimation of diversity. The genotypes UFRRJ MSC072, 042, 028, and 087 stood out with the highest number of fruits produced.

ABSTRACT - Based on its nutritional and economic value, the lima bean (Phaseolus lunatus L.) is the second most important species of the genus. It has high genetic diversity and potential for production and is considered an alternative food and income source. The objective of this study was to apply the restricted maximum likelihood/ best linear unbiased prediction (REML/ BLUP) methodology to estimate genetic parameters and predict genotypic values in F3 populations of lima beans. Twelve characteristics were evaluated in five populations with indeterminate growth habits (H39, H72, H53, H90, and H56). Model 83 from the Selegen program was used for analysis. Considering the genetic parameters, the highest values of genetic variance were for plant height and number of pods per plant. Pod thickness and seed width are favorable for breeding programs. Seed width selection gain was significant for populations H56 and H90 at 11.26 mm and 10.50 mm, respectively. As for the length and thickness of seeds, the gains were less significant, with population H53 showing the greatest gain. The REML/ BLUP methodology proved efficient in estimating genetic parameters and predicting gains in lima bean populations. The estimated selection gains indicated that the highest gains were obtained for plant height, the number of pods per plant, pod thickness, seed width, and the number of days to maturity. Populations H53 and H56 stood out for having large and white seeds, thus being potential populations for species improvement.

ABSTRACT Lima bean (Phaseolus lunatus) can be considered as an alternative income and food supply to farmers of the Brazilian Northeast. This crop has faced serious sanitary problems. Among the most important diseases that attack this crop, the anthracnose caused by Colletotrichum truncatum requires greater attention. This study aimed to determine the resistance of lima bean accessions to the isolates of C. truncatum. Detached leaves were used from ten lima bean accessions, originated from production fields in Paraíba State - Brazil. They were artificially inoculated with ten isolates of C. truncatum. The isolates were grown on bean-dextroseagar medium under temperature 27 ± 2 °C and a photoperiod of 12 hours, for fourteen days. The evaluations of the accessions’ resistance to the isolates were performed at 5, 7, 9, 11 and 13 days after inoculation (DAI), adopting a scale of notes, and the results were transformed in the area under the disease progress curve. The research was carried out in completely randomized design, in a 10x10 factorial arrangement (accessions x isolates) with 12 replications. The first symptoms of anthracnose on the detached leaves appeared from the third day after inoculation. The accessions were grouped from highly to moderately resistant or susceptive. The aggressiveness among C. truncatum isolates varied depending on the genetic variability of the lima bean accessions used. Accessions with significant resistance levels to anthracnose can be used as resistance sources in future breeding programs.

ABSTRACT The objective of this study was to evaluate potassium and chloride accumulation in, and the yield and quality of the potato tubers of the Asterix cultivar, under the application of two potassium fertilizer sources (KCl and K2SO4.2MgSO4) and their combinations. The experimental design was a randomized complete block with five treatments and four replications in a factorial scheme with a subdivided plot. The presence of greater than 61.8% of the recommended dose of chloride in potassium fertilization affects potato plant growth, with less dry matter accumulation in the aerial part. This does not occur in the tubers because of lower nutrient translocation to the tubers. K accumulation varies between levels depending on the companion ions of the sources. Throughout the cycle, the amount of chloride increased in the aerial parts and tubers with an increase in the percentage of KCl. The total productivity is affected by the use of a combination of potassium sources in different proportions, with a maximum yield of 41.3 t ha-1 with a combination of 64.5% KCl and 36.5% K2SO4.2MgSO4. Soluble solids did not vary with the sources at a dose of 180 kg ha-1 K2O.

ABSTRACT Lima bean is an important crop in Northeastern Brazil and a source of food and income for farmers in the region. However, there have been few genetic studies on this species, which limits the knowledge available for use in breeding programs. The objective of this study was to estimate the relationship between cycle and production traits using canonical correlation analysis and to identify traits that can be used for the indirect selection of lima bean. The experiment was conducted at the Department of Plant Science of the Universidade Federal do Piauí, Teresina, in a randomized block design with five replications, in which 11 agronomic traits from six lima bean populations in the F3 generation originating from biparental crosses were evaluated in 2019. The data were subjected to canonical correlation analysis using the virtual environment R. The results showed that only the first coefficient of the canonical pair was significant (r = 0.5531) by the quisquare test, suggesting that the studied groups were not independent, as the cycle traits showed coefficients of large magnitudes in the relationship between groups. The canonical correlation results suggested that there is a linear association between cycle and production traits in lima beans, in which days to flowering, days to maturation, pod length, seed width, and seed thickness contribute the most to the association between groups.

ABSTRACT Compaction modifies the structural arrangement and essential functions of soil pores. In this context, the objective of this study was to evaluate the impact of different compaction levels in an Argissolo Amarelo (Ultisol) on the physical-hydraulic attributes that indicate the functionality of soil pores. The experiment was conducted using 0.05 x 0.05 m soil cylinders with 4 compaction levels (CL): 61, 71, 82 and 92%, and at each CL, the pore-size distribution, intrinsic soil air permeability (Kair), pore continuity index N, soil water characteristic curve and cumulative pore-size frequency were quantified under a completely randomized design. The increase in CL did not impact the amount of micropores, but reduced the amount of macropores to values lower than the minimum required from the CL of 82%. The increase in CL caused reductions in N index, Kair and aeration porosity, but with different amplitude depending on the CL and the water tension in the soil. CL above 61% reduced the water content at the tension range between 0 and 6 kPa and, as a consequence, increased the percentage of aeration pores, besides promoting greater water retention within the range between 10 and 1500 kPa. The evaluation of the physical-hydraulic attributes of the Argissolo Amarelo (Ultisol) revealed that the increase in the compaction level altered soil structure, reduced and formed pores that were poorly continuous and less permeable to air flow and, despite the higher water retention at the higher tensions, promoted lower available moisture content.

ABSTRACT Environmental degradation impacts negatively the diversity and quantity of invertebrates living in the soil, mainly in semiarid regions. Generally, a high diversity of invertebrates indicates good biofunctionality and sustainable use of the soil. We evaluated the effects of 14 years of grazing deferment and the presence of the native trees Mimosa tenuiflora and Cnidoscolus quercifolius on the soil mesofauna of a degraded Caatinga area, according to the χ 2 test, applied to assess the abundance of these microorganisms. The grazing deferment alone more than tripled the soil mesofauna. The abundance of the mesofauna under M. tenuiflora canopies increased by a factor of 3.17 and 3.41 in grazed and ungrazed areas, respectively, and under C. quercifolius canopies increased by a factor of 22.6 in the ungrazed area. The effect of M. tenuiflora in the grazed area was similar to 14 years of grazing deferment. The quantity of mesofauna under C. quercifolius canopies after 14 years of grazing deferment was 6.6-fold higher than that under M. tenuiflora canopies, under similar conditions. The grazing deferment and trees, especially C. quercifolius, increased the soil mesofauna; however, full recovery of such organisms in degraded Caatinga areas may need more than 14 years. Considering the current scenario of increasing environmental degradation, our findings regarding the relationships between soil mesofauna, grazing deferment and native trees are important to devise strategies and procedures for the recovery of degraded areas in the Caatinga biome.

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 As a fresh food, sweet potatoes are highlighted for their taste and appearance. In the industry, they are valued for their starch and sugar content. In both scenarios, much attention has been given to the composition of bioactive compounds. The application of abiotic stresses seems to induce an overproduction of these compounds in some vegetables. The objective was to examine the influence of harvest time on the synthesis and accumulation of bioactive compounds in varieties of minimally processed sweet potatoes with different flesh colors. Sweet potato cultivars (Beterraba, Jerimum, Mãe de Família Roxa, and BRS Cuia) were harvested at 120, 150, and 180 days after planting, then subjected to minimal processing and stored at 5 ºC for 10 days. The most recommended time for harvesting sweet potatoes in semi-arid conditions for minimal processing by the industry is between 150 and 180 days. This is the period when the sweet potatoes exhibit the best quality for fresh consumption, as detected in ‘Mãe de Família Roxa’ and ‘Jerimum’. ‘BRS Cuia’ harvested at 120 days showed the highest phenolic compound levels, the highest polyphenol oxidase and peroxidase enzyme activities, and the most intense browning symptoms. In addition to its starch content, it can be used as a raw material for the extraction of phenolic compounds of interest. ‘Beterraba’ showed low sugar values, rendering them unfavorable for fresh consumption or minimal processing. However, this cultivar also exhibited a high content of carotenoids, making them bio-factories for the food and pharmaceutical industries.

ABSTRACT Quantifying soil gas emissions is costly, since it requires specific methodologies and equipment. The objective of this study was to evaluate modeling by nonlinear regression and artificial neural networks (ANN) to estimate CO2 emissions caused by soil managements. CO2 emissions were evaluated in two different soil management systems: no-tillage and minimum tillage. Readings of CO2 flow were carried out by an automated closed system chamber; soil temperature, water content, density, and total organic carbon were also determined. The regression model and the ANN models were adjusted based on the correlation of the variables measured in the areas where the soil was managed with no-tillage and minimum tillage with data of CO2 emission. Artificial neural networks are more accurate to determine correlations between CO2 emissions and soil temperature, water content, density, and organic carbon content than linear regression.