Chicken manure is accessible to family farmers, is produced in large volumes, and has a low cost. Therefore, it can be an alternative to increase the productivity of sweet potatoes (Ipomoea batatas), which is a culture of socioeconomic importance. The objective of the study was to evaluate the productivity of sweet potatoes under different doses of chicken manure, with and without liming, comparing to the use of chemical fertilizer NPK, in very clayey soil, from the perspective of economic efficiency. The experiment was conducted in the field from September 2019 to March 2020 in Manaus, Amazonas, Brazil. The experimental design was in randomized blocks with four replications, in a split-plot scheme 2 × 5 + 1 (presence or absence of liming; five doses of chicken manure; and NPK, respectively. The evaluated parameters were: total and commercial productivity; number of total and commercial tuberous roots; harvest index; individual fresh mass, length, and diameter of tuberous roots. The effect of chicken manure was not influenced by the liming and there are no differences in agronomic values related to NPK. The dose of chicken manure that results in maximum production of the queen sweet potato variety is approximately 13 t ha-1, producing 25.2 t ha-1, while the resulting dose in maximum profit is approximately 12 t ha-1 with a production of the 25.1 t ha-1. The selling production directly to the final consumer increased profit by approximately 57.3%. Purchasing the input directly from the manufacturer reduced costs by approximately 74.5%. The use of chicken manure has a greater economic advantage compared to NPK in very clayey soil.

The palm tree Euterpe precatoria Mart. is distributed all over the amazon region. The extractive exploitation mainly in coastal communities, where its use is essential in food, presents insufficient to attend a business model in isolated communities. As a result, management plans are required for the survival of this species. One of the primary limiting factors for seedling growth is light, with a view to its direct link with the photosynthetic efficiency. Among the main factors linked to the photosynthetic efficiency of plants and therefore to their establishment and development in different environments, is the concentration of chloroplastidic pigments (chlorophyll a, b and carotenoids). Based on the assumptions pointed the aim of this study was based on obtaining of knowledge and the potential of applicability on the production system of plant bags of this species from possible physiological characteristics of adaptability developed by E. precatoria Mart seedlings submitted to different conditions irradiance availability. Particularly, on the regulation of the concentrations of chloroplastidic pigments. Among the evaluations carried out in this work it can be said that Euterpe precatoria under different light intensities, proved probably acclimatized. This behavior suggests that the species tolerates environments with different levels of irradiance, about the increase of biomass and carotenoid content and chlorophyll a, there is no significant differences and showed higher levels for chlorophyll b in shaded environments (Engel & Poggiani, 1991; Kahn & De Granville, 1992).

Dead cover, or mulch, consisting of plant residues, plays an important role for the success of diverse agricultural crops, working as an insulating layer protecting the soil from daytime temperature variations and maintaining the soil moist and rich in organic matter. Cowpea is a source of proteins, carbohydrates, vitamins and minerals. Its importance in the North, Northeast and Midwest regions of the country is associated with economic and social aspects, since it is an important food for low-income populations, supplying their nutritional needs. This study was carried out under greenhouse conditions in Manaus, state of Amazonas, with the purpose of assessing the effect of different dead covers on the agronomic characteristics of cowpea cultivars. It consisted of a completely randomized design in a 4 × 4 factorial arrangement. The treatments comprised four cowpea cultivars (BRS Caldeirão, BRS Tumucumaque, BRS Guariba and BRS Tracuateua) and three species of cover plants (Brachiaria decumbens, Brachiaria ruziziensis and Mucuna pruriens) and one control treatment, without soil cover, in a total of 16 treatments, with four replications and two plants per experimental unit. Analysis of variance was applied to the data, and the means were compared by the Scott-Knott’s test at 5% probability level. The following characteristics were examined: number of pods per plant, pod length, number of seeds per pod, weight of shoot dry matter, and grain yield. Mulching provided better results for all characteristics assessed in the four cultivars when compared to the control. BRS Caldeirão is the recommended cultivar for the state of Amazonas and the other regions with similar edaphoclimatic characteristics (high air temperature, rainfall, air humidity, and low-fertility tropical soils) because it exhibited the greatest number of pods per plant, number of seeds per pod, shoot dry matter, and the highest average grain yield (Freire Filho et al., 2011; Souza et al., 2016).

The Euterpe precatoria Mart. palm. (Acai-do-Amazonas) has been investigated with the aim of sustainability. The palm that is mainly used for basic nutrition of local populations, could also form the basis for models of self-sustained technological and industrial development. The extractive exploitation mainly in riverside communities, where its use is essential in food, it presents insufficient to attend a business model in isolated communities. Therefore, the study was based on obtaining knowledge and its potential applicability in the production of seedling, by increasing levels of irradiance in order to evaluate its growth in diameter, height and number of leaves. In the analysis of growth in different irradiation levels E. precatoria Mart. showed no significant difference in height, the diameter had high development in seedlings subjected to higher levels of irradiance and the number of leaves was higher in the environment with lower irradiance index. The behavior exhibited by the species suggests that E. precatoria tolerates environments with different levels of irradiance.

Brazilian origin species Enterolobium contortisiliquum (Vell.) Morong (Fabaceae) is distributed from north to south of the country. The species is a pioneer and important in the manufacture of furniture, boats and canoes, and presents easy handling also being significant for degraded areas recovery programs. As a result, management plans are necessary for the survival of this species. In the context of reforestation and recovery of degraded areas, the production of seedlings of native forest species occurs in nurseries and the quality of these plants depends on several factors, among which, the composition of the substrates is a factor of great importance for having its physical, chemical and biological characteristics directly linked to the growth of the seedlings. The study was based on obtaining knowledge and potential applicability in seedling production, subjecting it to different substrates, in order to evaluate their growth in height, diameter, number of leaves and biomass. The behavior presented by the species suggests its potential for reforestation turned to production and conservationism, since it revealed tolerance to the various types of substrates and better results with the use of organic matter added to the substrate.

In this study, 14 quantitative traits were evaluated, divided into five distinct categories, related to the plants, leaves, flowers, fruits and seeds of seven Mallow accessions belonging to the NUSEC/UFAM germplasm collection. With the characteristics measured, the genetic variability of the accessions was evaluated, aiming at the genetic improvement of the culture. Through the analysis of variance, it was possible to assemble and propose the 14 agronomic descriptors, being that with the application of the clustering method (UPGMA), which generated a dendrogram of dissimilarity, it was possible to divide the seven genotypes into two distinct phenotypic groups, and their subgroups. The study showed that there is a great divergence between the accesses and the recommendation for the crossover is between the accesses ANÃ/MAC, ANÃ/MAQ and PIN/BER. The high heritability observed for the characters analyzed suggests the phenotypic value as a reliable measure for selection of the genotypes studied.

Cassava production in Amazonas state deserves to be highlighted due to its great historical, social, and economic importance. Weed competition severely constrains cassava production in Amazonas. The use of cover crops is safe and very efficient at eliminating weeds while keeping the soil covered. The objective of this study was to evaluate physical properties of soil and glyphosate residues in storage roots as a function of the weed management in cassava. The experiment was carried out in a randomized complete block design with five treatments and five repetitions. The treatments were biological control with two species of cover plants (Brachiaria ruziziensis and Mucuna pruriens), chemical control, mechanical control, and treatment with no weed control. The cover crops characteristics evaluated were dry weight, the percentage of cover, and rate of decomposition of plant residues. In the soil, the bulk density and total porosity were determined. The contamination of the storage roots was evaluated based on the analysis of glyphosate residue. Brachiaria ruziziensis presented more dry weight and higher percentage of cover compared with M. pruriens, and both cover crops showed very similar decomposition rates. The physical properties of soil were unaffected by any treatment evaluated. There was no detection of glyphosate and its metabolite, aminomethylphosphonic acid (AMPA), in any treatment evaluated. Chemical control with glyphosate is not able to contaminate cassava storage roots.

The seed yield of guarana (Paullinia cupana H.B.K. var. sorbilis) is affected by weeds. Management is difficult for Amazon farmers and ranchers, owing to the hot and humid climate prevailing in the region, which makes mechanical control inefficient and leads farmers to the decision to use herbicides. Herbicide damage to this species is unknown. The objective of this study was to evaluate glyphosate damage to the development and quality of guarana seedlings. The treatments consisted of glyphosate doses at concentrations of 0, 126, 252, 540, 1080, 2160 and 3240 g a.e. ha−1 and were evaluated for 60 days, in two applications. Analyses were performed for biometrics, seedling development, anthracnose and Injury characteristics. Glyphosate caused symptoms of Injury in all doses applied, but lower doses did not interfere with seedling growth and development. There was a correlation between anthracnose severity and increased glyphosate dose. When applied correctly, glyphosate can be an integrated weed management tool for use in guarana crops.