Abstract in English:

ABSTRACT Phosphorus (P) is an important nutrient for obtaining high yields and has been the one that most often limits production. The objective of this study was to evaluate the agronomic performance of onion cultivars as a function of phosphate fertilization. The experiments were installed at the Rafael Fernandes Experimental Farm, of the Federal Rural University of the Semi-Arid Region, Mossoró-RN, Brazil, from July to October 2016 and from June to October 2017. The design used was randomized blocks, in a 2 x 6 factorial scheme, with four replicates. The treatments consisted of the combination of two onion cultivars (IPA11 and Rio das Antas) and six P doses (0, 60, 120, 180, 240 and 300 kg ha-1 P2O5). The economical doses of P, associated with the maximum marketable yields of onion were estimated at 212.45 and 207.65 kg ha-1 of P2O5, respectively for the cultivars IPA 11 and Rio das Antas. In general, the cultivar Rio das Antas was more productive than IPA 11, in the two growing periods.

Abstract in English:

ABSTRACT Nasturtium (Tropaeolum majus L.) is an unconventional plant or vegetable grown for ornamental, food and medicinal purposes. However, information on cultivation of the species involving organic residue is incipient. Therefore, aimed to evaluate plant growth, flower yield, and nutrient contents of leaves and flowers of Nasturtium cultivated with addition of chicken manure. Five doses of chicken manure were studied, applied in the soil incorporated (I) (1, 6, 10, 14 and 19 t ha-1) and cover (C) (1, 6, 10, 14 and 19 t ha-1) forms, using the experimental array Plan Puebla III, leading to nine combinations of doses and forms of adding the chicken manure, in randomized blocks with four replicates. The greatest plant height (35.75 cm) was achieved at 168 days after transplanting (DAT) under 10 t ha-1 I and 10 t ha-1 C. The greatest yield terms of in number (15.4 million ha-1) and fresh (10.45 t ha-1) and dry weights (0.849 t ha-1) of flowers were found by using doses close to 10 t ha-1 I and 10 t ha-1 C. To obtain the best development and yield of Nasturtium flowers, 10 t ha-1 I and 10 t ha-1 C of chicken manure should be used.

Abstract in English:

ABSTRACT Shading screens have been extensively used in leafy-vegetables production system. Nevertheless, there is still a substantial lack of knowledge regarding the effects of this technology on the performance of non-conventional vegetables such as jambu, a typical staple food with social and economic importance for the Amazon region. This study thus aimed to evaluate the effects of shading screens on the agronomic performance of two jambu varieties. The experiment was performed in a randomized block design, in a 4 x 2 factorial scheme (shading screens and varieties), with four replications. Plants were then evaluated for morphophysiological and yield parameters. As an outcome, there was no significant interaction between shading screens and varieties for assessed variables. On the other hand, the shading screen itself affected significantly jambu varieties yield. The 50%-shading screen for instance provided both higher fresh weight accumulation and higher shoot water content. Moreover, 50%-shading screen led to an increase in both productivity (Kg m-2) and yield (bunch m-2) by 46%, respectively. The use of 50%-shading screen improves the agronomic performance of jambu, hence being a suitable technological alternative available for the farmers.

Abstract in English:

ABSTRACT The MeJA has been shown to be promising in reducing the damages caused by cold and maintaining the quality in several products. Nevertheless, few studies are conducted with flowers and there are no studies of its use in bird of paradise. The objective of this study was to determine whether the pulsing application with MeJA submitted to cold storage promotes physiological changes of the bird of paradise. Flowers were placed in solutions of 200 g L-1 sucrose added with 100, 250 and 400 μmol L-1 MeJA and control without MeJA, for 24 h. The stems were transferred to containers with water at 5 ºC for 28 days. During storage, the water absorption, transpiration and fresh mass were reduced, while the extravasation of electrolytes and phenolic compounds increased. The application of MeJA did not reduce the loss of fresh mass and extravasation of electrolytes. The application of 400 μmol L-1 MeJA has increased peroxidase activity since day 14 of storage. It is concluded that the application of MeJA with pulsing under refrigeration does not promote positive physiological changes for the maintenance of the quality in bird of paradise flowers.

Abstract in English:

ABSTRACT Increases in plant density associated with the use of plant growth regulators, aside from modifying the plant architecture, can also change the maize yield performance. This study aims to investigate the yield components and grain yield of maize hybrids with contrasting leaf architecture, in response to different plant populations and trinexapac-ethyl rates (TE). Field experiments were conducted in two growing seasons, in a (5 x 5) factorial randomized block design. The treatments consisted of: five plant population (40, 60, 80, 100, and 120 thousand plants ha-1) and five TE rates (0, 100, 200, 300, and 400 g a.i. ha-1), with four replications, using the hybrids 2B710 HX and Status TL. We evaluated the number of rows per ear, ear length, number of grains per row, 1000-grain mass, and yield. An increased plant density reduces ear length, number of grains per row and 1000-grain mass, without changing the number of grain rows per ear. TE rates increases ear length and number of grains per row and reduces 1000-grain mass, mainly under favorable cultivation conditions. TE interacts with the plant density, changing the maize yield components with increases in grain yield, but these gains variy, according to the environment and genotype characteristics.

Abstract in English:

ABSTRACT This study evaluated the effects of the rates and timings of prohexadione-calcium (prohexadione-Ca) application on shoot growth, tuber yield, and quality of two potato cultivars (Agata and Mondial). An experiment with each cultivar was carried out in a greenhouse using a randomized block design with four replications. Treatments consisted of a control and single or sequential foliar applications of prohexadione-Ca at the rate of 50 or 100 g ha-1 (50 g ha-1 applied once, 50 g ha-1 applied twice, 50 g ha-1 applied three times, 100 g ha-1 applied once, 100 g ha-1 applied twice, and 100 g ha-1 applied three times). Prohexadione-Ca application changed the distribution pattern of tuber size in both cultivars. A rate of 100 g ha-1 prohexadione-Ca was applied three times between the stages of tuber initiation and tuber bulking, making the haulm length of the plants short for a long time. Prohexadione-Ca application did not alter the tuber yield and quality of the cultivar Agata, but 50 g ha-1 applied three times or 100 g ha-1 applied twice increased tuber yield in the cultivar Mondial. Only in the cultivar Mondial, 50 g ha-1 prohexadione-Ca applied three times increase tuber dry matter, starch, and protein contents.

Abstract in English:

ABSTRACT A strategy for genetic improvement of coffee Coffea canephora plants is to aggregate through artificial crossings the characteristics of the Conilon botanical variety, such as shorter height and drought resistance, with the higher average grain size and resistance to pests and diseases of the Robusta variety. Efficiently separating the clones into these two groups with the aid of appropriate analytical procedures makes field tasks easier for professionals and, thus, allows the systematic production of intervarietal hybrids. This study verifies if the non-parametric discriminant analyzes of the k-nearest neighbors (k-NN) and k-average neighbors (k-AN) would be able to correctly classify 130 coffee clones in their botanical varieties previously designated as Conilon, Robusta and Intervarietal Hybrids populations from ten quantitative agronomic characteristics, including the processed coffee beans yield, considering the existing population genetic divergence. These characteristics were found to be good discriminatory variables and the discriminant analyzes k-NN and k-AN, based on the principle of similarity by neighborhood, classified the clones with high hit rates. The k-AN discriminant analysis was able to better discriminate intervarietal hybrids from the group clones Conilon. The results correctly reflected the genetic diversity between the botanical varieties and intervarietal hybrids of Coffea canephora, allowing us to conclude that these classification methods can assist breeders in the main task of discriminating Conilon from Robusta clones.

Abstract in English:

ABSTRACT Forage-legume systems are a sustainable and competitive alternative for improving pasture yield and quality because of the symbiotic nitrogen fixation capacity and high nutritional value of legumes. This study aimed to evaluate the forage mass, nutritional value, and nutrient export rate in three forage systems (FS): FS1, with elephant grass (Pennisetum purpureum) (EG), annual ryegrass (Lolium multiflorum) (AR), and spontaneous growth species (SGS); FS2, with EG + AR + SGS + arrowleaf clover (Trifolum vesiculosum); and FS3, with EG + AR + SGS + forage peanut (Arachis pintoi ). The experiment was arranged in a completely randomized design, with three replicates, and repeated measures over time. Results of pre-grazing forage mass were 3.5, 3.8, and 3.9 t/ha, and crude protein export were 1.4, 2.1, and 2.3 t/ha, for the treatments FS1, FS2 and FS3, respectively. Highest crude protein, in situ dry matter digestibility and total digestible nutrients, and lowest neutral detergent fiber were found in the intercropping system with forage peanut, especially in winter. Nutritional values were also better in legume-systems than the non-legume system.

Abstract in English:

ABSTRACT In no-tillage systems, oats are one of the species most used as a cover crop in the subtropical region of Brazil. This study aims is to determine a set of chemical and physical properties of five Oxisols after surface liming, and to determine whether these properties are related to the shoot dry mass production of white oat (Avena sativa L.) variety IPR Aphrodite, in order to establish a model to predict its yield.. For this purpose, a field experiment was conducted during 2015 and 2016 in Londrina County in the State of Paraná with samples of B horizon collected from five Oxisols with clay content ranging from 15-80 dag kg-1 arranged in microplots since 2004. Soil pH in CaCl2, calcium, magnesium, potassium, potential cation exchange capacity (CEC), base saturation, microporosity, total porosity, field capacity, permanent wilting point, clay and sand of the Oxisols were the parameters that most influenced the dry mass production of white oats. Oxisol extrinsic factors such as values pH and base saturation, as well as the calcium and magnesium contents, positively altered with surface liming, boosting the production of oat dry mass production.

Abstract in English:

ABSTRACT Inferior quality water can be used by agricultural producers in arid and semi-arid regions due to the lower availability of good-quality water. Therefore, the objective was to identify the influence of irrigation with saline water on gas exchange and leaf contents in corn (Zea mays L.) crop. The work was conducted in the field, in the experimental area of ​​the Experimental Farm of the University of International Integration of Afro-Brazilian Lusofonia (UNILAB), Redenção-CE. The experimental design used in the research was randomized blocks, with five treatments: 1.0; 2.0; 3.0; 4.0 and 5.0 dS m-1 and four repetitions. At 45 days after sowing (DAS) the gas exchange variables were evaluated: transpiration, stomatal conductance, photosynthesis, internal CO2 concentration, water use efficiency and leaf temperature. And at 110 DAS the contents of N, P, K, Ca and Mg in plant leaves. The saline stress due to saltwater irrigation leads to a reduction in photosynthesis, stomatal conductance, internal CO2 concentration and transpiration in field maize plants. Salt stress reduces the levels of N, P, K, Ca and Mg mineral elements in maize leaves.

Abstract in English:

ABSTRACT In the northeastern of Pará, cowpea is one of the main protein sources of the population. This study aimed to evaluate the effects of liming, the P and K mineral fertilization, and the combination of seed inoculation with Rhizobium associated with mineral N supplementation in the growth and production of cowpea cultivars. Two experiments were carried out in two consecutive years at the Federal Rural University of Amazonia (Capitão Poço-PA). A randomized block experimental design with subdivided plots was used with four replications, two cowpea cultivars (BRS Tapaihum and BRS Marataoã) and six fertilization and liming treatments: i) without fertilization and without liming; ii) P and K mineral fertilization, liming and seed inoculation with Rhizobium; iii) P and K mineral fertilization and seed inoculation with Rhizobium; iv) N, P and K mineral fertilization and liming; v) P and K mineral fertilization and liming; and vi) N, P and K mineral fertilization, liming and seed inoculation with Rhizobium. Cowpea responded to liming and P and K mineral fertilization, but not N fertilization. There was no difference between the supply of N through seed inoculation or mineral fertilization. Thus, it is suggested to inoculate seeds with Rhizobium in order to maintain the soil N reserve.

Abstract in English:

ABSTRACT The cultivation of grasses in sewage sludge (SS) with aeration has the potential for stabilization of sludge organic matter in the production of organic fertilizer. Thus, the objective of this work was to evaluate the cultivation of Urochloa brizantha and Pennisetum purpureum under aerated system on the chemical and biological attributes of SS to obtain a matured organic fertilizer. The study was conducted in a randomized block design in a 2x2+2 factorial scheme with four replications. Factors consisted of cultivation of P. purpureum or U. brizantha in SS, with or without intermittent aeration. Control treatments were SS without cultivation, with or without aeration. Sewage sludge was collected in layers and the chemical and microbial attributes were evaluated. There was no significant difference between treatments for grass dry matter. The C/N ratio was not matched with organic fertilizer stabilization due to similar losses of C and N (~7%). However, microbial activity was reduced in the presence of plant cultivation demonstrating improvement in the properties of the organic fertilizer produced. Through uni- and multivariate analysis, organic fertilizer produced from SS aerated and cultivated with P. purpureum showed matured organic matter.

Abstract in English:

ABSTRACT The objective of this study was to evaluate the diversity and abundance of edaphic fauna organisms in single and intercropped systems of sweet potato (Ipomoea batatas) and ecologically-based popcorn (Zea mays) in Red Oxisol, in the Northwest region of the state of Rio Grande do Sul, Brazil. Four sweet potato cultivars were used in single systems and intercropped with popcorn: BRS Amélia, BRS Rubissol, BRS Cuia and Crioula. The soil fauna assessment was carried out using PROVID-type traps. Richness, abundance and the dominance indices of Shannon (H’) and Simpson (D) were determined. The orders Coleoptera, Hymenoptera, Collembola and Orthoptera, were dominant in both cultivation systems. The single cultivation showed a greater number of organisms in the orders Isopoda and Collembola, whereas in the intercropped system, the orders Lepidoptera and Hymenoptera stood out. The intercropping cultivation of sweet potato and popcorn shows highest diversity and abundance of soil organisms compared to the single cultivation.

Abstract in English:

ABSTRACT Eugenia involucrata is an important Brazilian forest species, which it can be used for timber, such as firewood and charcoal, and non-timber purposes, for culinary and medicinal use. Considering the limitations of its seminal reproduction, vegetative propagation, particularly by micropropagation, becomes an alternative for plantlets production. In this study we evaluated the effect of the phytoregulators 6-benzylaminopurine (BAP) and 3-indolebutyric acid (IBA) on the in vitro multiplication stage of nodal segments. The experiment was carried out in a completely randomized design, in a 3 x 4 factorial array, the main factors were BAP (0; 0.1 or 0.2 µM) and IBA (0; 10; 20 or 30 µM). After 60 days of in vitro inoculation, evaluations on the the number of buds, number of shoots, number of leaves, callus formation (%) and number of roots per explant were carried out. BAP had not significant effect, however, the use of IBA alone favours the callogenesis and negatively affected leaves, shoots and roots formation. A moderate multiplication rate was obtained when considering in vitro bud formation. BAP and IBA are dispensable in in vitro multiplication of E. involucrata.

Abstract in English:

ABSTRACT Owing to numerous health benefits, the cultivation of medicinal plants has significantly increased. Achillea millefolium L. (common names: milefoil, yarrow) is attributed important medicinal properties. Consumers of herbal medicinal products demand for production systems based on ecological farming principles, thus an interesting technology would be application biostimulant based on humic acids. The objective of this study was to evaluate the rooting and initial performance of Achillea millefolium in response to the use of humic acids (HA) isolated from composted cattle manure and poultry litter and applied in different concentrations (0, 10, 20, 30, and 40 mmolL-1 of HA) at the propagation phase. Rooting and plant biomass accumulation were analyzed. Humic acids derived from poultry litter promoted root development and increase of fresh biomass and total dry mass, proving their biostimulant effect. The optimal concentration of humic acids estimated for the initial development of A. millefolium was 22.25 mmolL-1.