Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

The objective of this study was to evaluate the effects of boron at different doses and times of application on BRS RB331 Ipyporã. Two outdoor pot tests were conducted at the 2016/17 crop. In both tests, the treatments were represented by four doses of boron and control and two times of application in a randomized block design in a factorial scheme with three replications, and each plot represented by a pot with one plant. The substrate was composed of sand:soil (3:1). Fertilization was performed according to the need, considering the treatments. Substrate samples were analyzed. This experiment evaluated the number of vegetative tillers and plant height in two different times, chlorophyll and leaf analysis before the beginning of floral differentiation; flowering onset, number of reproductive tillers, and number of fully expanded inflorescences; quantification, viability, and pollen germination in full flowering. Seeds were evaluated for percentage of number and weight of full and empty seeds, germination, germination speed index, first germination count, and viability. Fresh and dry biomass and dry mass of the aerial part and roots were evaluated at the end of the experiment. The variables were analyzed using Assistat 7.7 software. Boron, applied at different doses and dates, did not affect the production (yield and quality) of BRS RB331 Ipyporã seeds. The phytotechnical components of the BRS RB331 Ipyporã hybrid were not influenced by the addition of boron. Boron had a positive effect on root production of the hybrid BRS RB331 Ipyporã.

Grain legumes in tropical areas are of great importance as a food source, especially in rural communities. Little is known about their adaptability and behavior in non-alluvial soils of the Peruvian Amazon. Our objective was to assess the agronomic behavior of cowpea varieties in non-alluvial soils. The experiment was performed in completely randomized design with four treatments and four repetitions. Each experimental unit consisted of five rows of 6 m length by 0.5 m between plants and 1 m between rows. The variables evaluated were: plant height (cm), number of pods, pod length (cm), number of grains per pod, grain length (mm), grain width (mm), and weight of 100 seeds (g). An analysis of variance and Tukey’ test at 5% probability were used to determine significant differences between treatments. Results showed significant differences between varieties according to the evaluated variables. The red cowpea presented significant differences for the agronomic characteristics in plant height (62.83 cm), grain length (8.68 mm), and weight of 100 seeds (16.87g) in relation to the other varieties. The Chiclayo Olho Preto variety stood out only in grain width (5.46 mm), and the Chiclayo Vermelho in pod length (19.58 cm). The red cowpea has the potential to be cultivated preliminarily in larger-scale areas in the Yurimaguas district.

Guarana (Paullinia cupana Kunth, Sapindaceae) is a cultivated plant typical of the Amazonian biota. Among the pests that attack the crop, mite has not been recorded. Thus, recording the first occurrence of Tetranychus mexicanus (McGregor, 1950) (Acari: Tetranychidae) in guarana trees and characterize the damage is paramount. The specimens were collected from plants of BRS-Maués variety kept in a greenhouse in Manaus, Amazonas. The mites, in the field (in vivo) and in the laboratory (mounted on a microscope slide), and the damage were characterized and recorded on images. The recorded characterizations were compared with those in the literature for T. mexicanus. Mites were infesting more than 90% of the plants and causing severe damage. Thus, guarana is included in the list of host plants of T. mexicanus, which may cause damage to plants kept in a protected environment.

In scientific research, the repetition of the experiment and the selection of variables-response improve the precision of the results and make the conclusions more assertive, allowing generalizations from the joint analysis. However, there are no official rules about how many times experiment should be repeated, as well as which variables best discriminate the evaluated treatments. For this reason, this research aimed to estimate the number of repetitions of experiments and indicate the importance of morphoagronomic characters of lettuce cv. ‘Veneranda’. Data from four experiments were considered, in which four soil covers were evaluated (SoilTain DW® geosynthetic blanket, white and black polypropylene mulching and uncovered soil) in the completely randomized design, with five replications. The number of experiments was estimated by the repeatability coefficient and the importance of the characters, estimated by Singh criteria. In general, the repeatability coefficients were of medium magnitude, in which the number of measurements ranged from 1 to 9 experiments and, for yield, four experiments are enough to accurately indicate the best treatments. The most discriminant variables were the number of leaves (39.47%) and their length (20.79%) and plant height (17.06%); leaf width and root mass variables may be discarded in future studies (0% contribution). The results indicate that the execution of a single experiment, common in lettuce researches, does not allow accurate conclusions, and should be a criterion to be considered in the experimental planning.

This study analyzed characteristics associated with the agrobiodiversity maintained by farmers in babassu areas in the Médio Mearim, Maranhão, identifying local varieties of the main species cultivated in traditional swiddens, as well as the frequency of fruit tree species, vegetables, and medicinal and condiment plants present in home-gardens. Based on interviews conducted in 1,025 households in 207 villages, varieties of rice (36), cowpea (31), maize (20), and cassava (35) were reported. In the home-gardens, 46 fruit tree species, 29 vegetables, and 73 medicinal and condiment species were identified. To better understand aspects that influence the diversity of species and varieties, the results were analyzed according to 11 variables used as stratification criteria. The analysis indicated that significant differences in the average number of vegetables were observed in relation to landholding area and retirement benefit. For medicinal and condimental vegetables, differences were observed for age group of the household head, dependence on babassu extraction, and monetary income of the household. Regarding the diversity of fruit trees cultivated, differences occurred for all the variables analyzed, except for the education of the household head. Analyzing jointly the four main species of traditional swiddens, a positive association for greater diversity occurred in quilombola territories, and a negative association for beneficiaries of the Bolsa Família Program. These results confirm that swidden field is a peasant institution that persists, featuring a significant diversity of traditional varieties, which is not sufficiently affected by factors endogenous to the domestic unit of production.

Açaí (Euterpe oleracea) is a fruit with economic importance for the North region. However, little is known about the biometric characteristics of the varieties of this species. The study aimed to verify the differences in the biometric characteristics of three varieties of açaí fruits, occurring in the northeast mesoregion of Pará, Eastern Amazon. Ripe fruits of the varieties açaí chumbinho, açaí comum and açaí BRS-Pará were collected and then submitted to measurement of fresh mass, longitudinal and transversal diameter of the fruits; fresh and dry mass and moisture of pulp and seed; and the ratio between pulp and seed. The variety BRS-Pará obtained higher values ​​in the longitudinal and transversal diameter, fresh fruit mass, fresh and dry mass and pulp moisture. However, the chumbinho variety stood out in the percentage of fruit pulp with 36.85%. In the cluster analysis, based on the Euclidean distance, three evident groups were formed for the varieties BRS-Pará, chumbinho and comum. In the analysis of principal components, the group formed by the variety BRS-Pará presented the transversal diameter and fresh mass of the fruit and the seed as the most relevant variables. It is concluded that the variety BRS-Pará was superior in most of the variables. However, the chumbinho variety presented a higher percentage of pulp, which could be attractive for the exploitation of açaí fruits and an advantage for the producer of this variety.

The soil organic matter has a great importance for agriculture and is the result of the decomposition of plant and animal residues, root exudates, excrements and microorganisms, and is part of a natural cycle that is constantly changing. The humified fraction of organic matter makes the soil more fertile and contributes to the availability of nutrients to plants. This article aimed to evaluate the humic fractions (humic acids and fulvic acids) and total organic carbon of the soil under different cropping systems. The experiment was conducted at the Federal Institute Sertão Pernambucano, Campus Petrolina Rural Area, where three areas with different use systems were evaluated, of which were denominated: Vitis spp. (SPV), Pennisetum purpureum (SPC) and natural area of hyper xerophytic Caatinga (NAC). Soil samples were collected at a depth of 0-10 cm, for chemical fractionation and determination of total organic carbon. The NAC system provides more adequate conditions for SOM humification.

List of RCA AJAES reviewers

The objective of this research is to analyze whether there was economic growth in the floriculture sector during the COVID-19, sanitary crisis in the province of Cotopaxi. Therefore, a simple linear regression model was applied in order to relate advertising expenditures and their impact on income (sales). The study has a quantitative approach of correlational scope. Once the monetary figures of sales and advertising expenses were obtained from the financial statements presented by the Superintendence of Securities and Insurance Companies for the periods from 2016 to 2020, a convenience sample of eight flower companies was obtained. Said sample was managed under a parameter of reflecting an annual monetary amount without exception, in the study variables. The results obtained show that, there is no relationship of dependence of advertising expenses on sales at a low level of significance. Finally, it is concluded that there was no growth in the floriculture sector during the COVID-19 pandemic and, in comparison to other studies; the economic situation is derived in losses.

Subsidies in the world are used as a timely tool for the social and economic development of society. However, a subsidy without a focal objective can distort its effect.  Ecuador provides various subsidies to its population and among them is the fuel subsidy, which changed the state from being an exporter of oil to an importer of derivatives to meet its domestic demand. Throughout the country's history, the fuel subsidy issue has become a political strategy, which, when trying to be eliminated due to the level of resources used for its execution, has generated social and political commotion and economic imbalance. For this reason, the objective of this research was to determine the impact on the sales of the Garages Standard gas station due to the reduction of the fuel subsidy, through the evaluation of the income statements and the sales by product, which are the primary source of financial information of the company. The research method was quantitative based on bibliographic analysis and field study, corroborating the references obtained through the sources of information. Among the results obtained, it was determined that the reduction of the fuel subsidy had an unfavorable impact on the sales of the gas station, which had to resort to the sale of its assets to face the liquidity problems caused by the subsidy.