Recurrent selection can generate successive gains for characters of economic interest without causing genetic narrowing in the population. However, it has rarely been used in breeding programs in popcorn, especially when using full-sibling progenies to generate more expressive gains. The objective of this study was to estimate the genetic gain of the UENF-14 popcorn population through recurrent selection, and verify the evolution of the gains between the selection cycles four and eight. A total of 200 full-sibling progenies were evaluated in randomized blocks arranged in eight sets within three replicates in two environments; each set containing twenty-five progenies and six controls (selection cycles 4, 5, 6 and 7 of the UENF-14, BRS-Angela and IAC-125). The average height, prolificacy, 100-grain weight, ear weight, grain yield, and grain popping expansion of the plants were evaluated. In the selection of the thirty superior progenies for the eighth cycle, the Mulamba and Mock selection index was used, which generated estimated genetic gains of 4.60 for grain yield and 3.61% for popping expansion. The grain yield increased 111.99 kg ha-1 and the popping expansion increased 1.75 mL g-1 per cycle. The evolution of the cycles resulted in an accumulated genetic gain for the main characters of economic importance, allowing the prediction of success in the continuity of the recurrent selection.

The objective of this study was to evaluate the phytomorphological parameters of soybean in a crop-livestock system inoculated with Azospirillum brasilense. The experiment was conducted in Santa Maria, Brazil, for two agricultural years (2 Paper extracted from the doctoral thesis of the first author. 012/2013 and 2013/2014) in a randomized complete block design with three replications. In the winter, the black oat and ryegrass pasture was managed with sheep under different grazing systems: (I) - a conventional grazing (CG) system, where the animals remained in the pasture throughout the experimental period without any pasture height control; (II, III, and IV) - systems with post-grazing pasture heights of 10, 20, and 30 cm, respectively; and (NG) - one control without grazing. All treatments received two nitrogen doses (50 and 100 kg ha-1) and inoculation or no inoculation (A. brasilense). The soybean cultivar BMX Potência RR was sown using no-tillage on 16 November 2012 and 1 December 2013. In each plot, seven rows of plants with spacing of 0.45 m were used, and in four rows, the seeds were inoculated with the bacterium A. brasilense. The phytomorphological variables and grain productivity were evaluated. In a croplivestock system, soybean has better productivity when established on black oat and ryegrass pasture managed with post-grazing pasture heights of between 20 and 30 cm. Areas under conventional grazing in the winter led to smaller soybean plants with lower first and last pod heights. Inoculation with A. brasilense should not be used alone in soybean cultivation.

Rio Grande do Norte has mountain formations with edaphoclimatic conditions different from those predominating in the state, presenting deeper,acid soils, and milder climate. Among these formations, is the Santana mountain range, which is part of the Serra do Martins Formation. The objective of this work was to interpret the pedogenesis of the representative soils of the Santana mountain range through morphological, physical, and chemical characterizations of soil profiles and evaluate the effect of these attributes on the distribution of pedological forms along the landscape using multivariate analysis. Morphological, physical, and chemical analyses of seven soil profiles of the Santana mountain range were performed. The soils were classified according to the Brazilian Soil Classification System and the data subjected to multivariate analysis. The representative soil classes found were: LATOSSOLO AMARELO Distrófico argissólico; LATOSSOLO AMARELO Eutrófico argissólico; NEOSSOLO QUARTZARÊNICO Órtico típico; NEOSSOLO LITÓLICO Eutrófico fragmentário; NEOSSOLO REGOLÍTICO Eutrófico típico and CAMBISSOLO HÁPLICO Tb Eutrófico léptico. According to the analysis of the morphological attributes, the parent material had great influence on the formation of the different soil classes found in the Santana mountain range. The soil textural classes varied from sand to sandy clay loam. According to the analysis of the chemical attributes, the soil profiles presented acid reaction, great variation of base saturation, and low electrical conductivity. The multivariate analysis established groups of representative soil profiles of the Santana mountain range through the distinction of their physical and chemical attributes, mainly of subsurface diagnostic horizons.

In the present study, we evaluated the influence of agroforestry systems and traditional agriculture on the physical attributes and biologicals of soil, using as reference a native forest area in Paraty, RJ. Levels of total soil organic carbon, as well as oxidizable fractions and aggregate stability, were analyzed, in addition to the activity and carbon and nitrogen content in the soil microbial biomass, in the 0-5 cm layer, in two distinct seasons (dry and rainy seasons). The agroforestry systems and traditional agriculture maintain high levels of total organic carbon and its storage in more stable fractions. These systems provide the same conditions as those of the forest area for the aggregation of the soil. The microbial biomass was more responsive to variations in management and seasonality. The deployment of agroforestry systems contributes to the formation of a more diversified agricultural matrix, promoting improvements in the soil quality and connection with the remaining adjacent forest.

The genetic variability within the crop species Ipomoea batatas is broad, hence, in order to support future breeding programs it is of the utmost importance that germplasm banks be created, conserved, and characterized. Therefore, the objective of this work was to rescue and evaluate the genetic divergence in sweet potato accessions collected in traditional communities of Vale do Ribeira Paulista. Sweet potato samples were collected from quilombos, indigenous villages, caiçaras communities, and small farms. The study was conducted between February 2013 and August 2014 in a randomized block design with three replications. Genetic material included 95 collected accessions and two commercial cultivars. Morphological characteristics of the accessions were evaluated and distances in the genetic distance matrix were estimated by means of multi-category variables, the data being subsequently clustered by the Tocher method. Analysis of the relative contribution of each characteristic and phenotypic correlation of descriptors was also performed. Results evidenced wide genetic diversity among the sweet potato accessions collected in Vale do Ribeira, which were not grouped according to the collection point. The descriptors that contributed more than 60% of genetic diversity included: leaf size, general leaf profile, immature leaf color, petiole pigmentation, predominant branch color, branch secondary color, stem length, cortical thickness, predominant periderm color, and periderm color intensity. Correlations between morphological descriptors was observed in 22.26% of the paired traits.

Sweet potato is a promising crop in Brazil due to its potential for bioenergy production. However, little information on adequate chemical weed control is found for this crop. Thus, the objective of this work was to evaluate the effect of clomazone on 20 genotypes of sweet potato and the sensitivity of these materials to weed interference. A field experiment was conducted using an experimental design with four blocks arranged in split-plots. The sweet potato genotypes Brazlândia-Branca, Cariru-Vermelha, Princesa, Tomba-Carro-1 and UFVJM (01, 05, 06, 07, 08, 10, 14, 23, 26, 30, 35, 42, 43, 46, 48 and 49) were grown for 180 days under three weed managements (soils treated with clomazone, mechanically weeded and with no weed control). The plots consisted of the weed control methods and the subplots consisted of the sweet potato genotypes. Phytotoxicity, branch growth and yield were evaluated. Plants grown with no weed interference had larger branch length. The highest yields were found in clomazone-treated soils. Weed interference reduced 81 to 99.7% of the yield. The less susceptible genotypes to weed interference were UFVJM07, UFVJM10 and UFVJM35, and the most sensitive were Princesa and UFVJM01. The root yield of plants under chemical weed control was similar to or greater than those with mechanical weed control in 17 of the 20 genotypes evaluated.

Spatial variability of soil attributes affects crop development. Thus, information on its variability assists in soil and plant integrated management systems. The objective of this study was to assess the spatial variability of the soil apparent electrical conductivity (ECa), electrical conductivity of the saturation extract (ECse), water content in the soil (θ) and soil texture (clay, silt and sand) of a sugarcane crop area in the State of Pernambuco, Brazil. The study area had about 6.5 ha and its soil was classified as orthic Humiluvic Spodosol. Ninety soil samples were randomly collected and evaluated. The attributes assessed were soil apparent electrical conductivity (ECa) measured by electromagnetic induction with vertical dipole (ECa-V) in the soil layer 0.0.4 and horizontal dipole (ECa-H) in the soil layer 0.0-1.5 m; and ECse, θ and texture in the soil layers 0.0-0.2 m and 0.2-0.4 m. Spatial variability of the ECa was affected by the area relief, and had no direct correlation with the electrical conductivity of the saturation extract (ECse). The results showed overestimated mean frequency distribution, with means distant from the mode and median. The area relief affected the spatial variability maps of ECa-V, ECa-H, ECse and θ, however, the correlation matrix did not show a well-defined cause-and-effect relationship. Spatial variability of texture attributes (clay, site and sand) was high, presenting pure nugget effect.

In Brazil, studies on chickpeas (Cicer arietinum L.) have demonstrated the high productive potential of this crop, especially in the Cerrado areas of Cristalina, GO, and Brasília, DF. Due to dry winter climatic conditions, the North of Minas Gerais may be very suitable for the production of this crop. However, more information on chickpea sowing dates is needed. Therefore, the objective of the present study was to evaluate different chickpea sowing times in two municipalities of Minas Gerais State in Brazil: Montes Claros and Januária. The experiment was carried out in a randomized block design, comprising three sowing dates (12 May, 23 June, and 22 July, 2015), and seven replications. The cultivar used was BRS Aleppo, and the chickpeas were harvested 121 days after sowing. The variables evaluated included plant height, productivity, number of pods with one grain, and number of pods with two grains. The data were submitted to analysis of variance, and joint analysis of the experiments was performed. The highest yields were obtained when chickpeas were sown in May in Montes Claros, with a yield of 5.3 t ha-1. In Januária, chickpeas sown in May and June produced yields greater than 3.0 t ha-1. The plants sown in July, considered late for planting, were harvested during the rainy season, which compromised the quality and yield of the grains. In addition, maximum temperatures above 30ºC were recorded from September onwards in both locations, which also resulted in a reduction in the number of grains per plant. Thus, this sowing season is not recommended in the studied region.

Plasma technology is a fast, cost-effective, and pollution-free method that can be used in place of conventional methods to overcome seed dormancy. The goal of the present study was to determine the effect of different application times of atmospheric plasma on soaking and germination of Hybanthus calceolaria seeds in order to accelerate these processes. Helium plasma jet produced by dielectric barrier discharge was used to treat H. calceolaria seeds with applications of 1, 5, and 10 minutes. The treated seeds were characterized considering their weight variation during soaking, changes in electrical conductivity, and pH. It was found that germination depended on the plasma application time. The treatment of H. calceolaria seeds with atmospheric plasma for 1 minute provided 3.5 times greater germination in comparison to untreated seeds. Atmospheric plasma technology obtained by dielectric barrier discharge had potential of being used as a germination accelerant in H. calceolaria seeds. The treatment of H. calceolaria seeds using atmospheric plasma for 1 minute favored germination.

Wood is the main source of energy in the energy matrix of underdeveloped countries, in addition to having a significant participation in developing countries, ranking fourth in Brazil. Thus, this study aimed to determine a model for determining the energy density of forest species from the Cerrado. Samples of trunks and branches were collected from 34 forest species in an area of 10.15 ha located in the Cerrado region aiming for immediate analysis, i.e. the contents of ashes (ASH), volatile matter (VM), fixed carbon (FC), and higher calorific value (HCV). Data from dry and saturated mass were obtained in order to determine the basic density. The species presented values of VM ranging from 77 to 85.5%, ASH from 0 to 1%, FC from 14 to 23%, and HCV ranging from 18,282 to 20,121 GJ ton-1. A significant relationship was found between VM and FC (R2 = 0.9927) whereas no significant values were found between HCV and basic density. The average value of energy density considering the 34 species was 12,459 Mcal m-3. The estimated energy density of the area was 1,378,541 Mcal ha-1. The proposed model for calculating the energy density as a function of basic density favors energy surveys of areas to be explored since there is no need for calorific value analysis.