RCAAP Repository

Agriculture depends on biotic and abiotic factors, and one of them is allelopathy, defined as the chemical interference that one plant has on others, which can negatively affect germination. The objective of this work is to evaluate the allelopathic effects of Sorghum bicolor and Digitaria insularis on seed germination and initial development of canola seedlings (Brassica napus L.). A completely randomized design was used in a 2x5 factorial scheme (two extracts: D. insularis and S. bicolor) and five concentrations (0, 25, 50, 75, and 100%), with four replicates of fifty seeds, the plot being constituted by a 'gerbox' box containing 50 seeds evenly distributed. The variable analyzed were germination percentage (G), abnormal seedlings (AS), dead seeds (DS), length of the shoot (SL) and primary root (RL), total length (TL) of the seedling, shoot ratio (S/T), and root ratio (R/T). The aqueous extracts of D. insularis interfere in all variables studied, which compromises the formation of normal seedlings, regardless of concentration. The extract of S. bicolor expressed allelopathic effects only in concentrations above 75%. Both species can inhibit the initial development of canola plants.

As a crop that is rich in oligosaccharides, Jerusalem artichoke is considered one of the most promising plants for production because of its ability to survive in marginal lands, strong resistance to biotic and abiotic stresses, ease of conversion into biofuels, and use for food consumption. In the present study, the effects of propagule size on tuberous rhizome production and the physicochemical characteristics of Jerusalem artichoke were evaluated. Five propagule sizes of tuberous rhizome, 10 g (T1), 30 g (T2), 50 g (T3), 70 g (T4), and 90 g (T5), were used in a completely randomized experiment with 5 replicates and 11 plants per replicate. Harvesting was carried out 164 days after planting. The results showed that T1 resulted in the lowest emergence rate, number of tuberous rhizomes and aboveground fresh weight per plant of all the treatments. However, there was no significant difference among treatments in the tuberous rhizome dry weight, pH, titratable acidity, Brix, or reducing sugar. Propagule with tuberous rhizome of 30-50 g is recommended to achieve a high emergence rate and yield.

The essential oil of Bauhinia forficata collected in three locations, Rio Verde, Acreúna and Montividiu – GO, Brazil, had a satisfactory extraction with a yield of 0.038; 0.043 and 0.046%, and the relative density was 0.903; 0.901 and 0.903 g mL-1, respectively, and the positive solubility in ethanol. The percentage of mycelial inhibition in vitro of the essential oil mix was more efficient for the strains of S. sclerotiorum and A. flavus. Slight growth inhibition was observed for C gloeosporioides, which proved to be more resistant to essential oil concentrations used. The essential oil mix of Bauhinia forficata flowers proved to be a great option as an antifungal agent.

The Japanese pumpkin known as "Tetsukabuto" is the result of crossing selected lines of squash. Squashes are highly susceptible to weed interference due to slow initial growth, requiring more considerable attention as to their control. Studies focusing on the losses caused by weeds to Japanese pumpkin hybrids are scarce. Thus, this study aimed to evaluate the influence of weed control on the fruit yield of Japanese pumpkin hybrid cultivars. A randomized block design with four replications in a 3x4 factorial scheme was used. Three cultivars (Corina F1, Triunfo F1, and Takayama F1) and four weed control periods, without weed control, weed control from 0 to 30 and from 0 to 60 days after transplanting (DAT), and weed control throughout the crop cycle (continuous control) were evaluated. The harvest was carried out at 105 DAT, and it was evaluated population density of the weed community, yield, fruit diameter, fruit fresh mass, number of fruits per plant, pulp thickness, and internal fruit cavity thickness. The weed control from 0 to 60 DAT and continuous weed control resulted in the lowest weed population density and weed dry matter. The weed control from 0 to 60 DAT provided a higher number of fruits per plant, fruit diameter, fruit fresh mass, and thicker pulp. The highest development and fruit yield of Japanese pumpkin hybrids was observed when the plants were free from weed interference until 60 days after transplanting.

This study aimed to analyze the effect of two planting spacing on dendrometric characteristics and basic wood density of eucalyptus clones. The experiment in the municipality of Jataí-GO, Brazil, used a randomized complete block design with three replications, in which the spacing (3.0 m x 2.0 m and 3.0 m x 3.0 m) were allocated to the plots and the clones (3335, 3336 and 3487) in the subplots. Diameter at breast height (dbh), total height (HT), total volume (VT), basic density (db), stem biomass (BS), leaf and branch biomass (BLB) and total biomass (BT) were evaluated. The data were submitted to analysis of variance, followed by the Tukey test for comparison of means at the 5% probability level. It was found that the dbh and VT characteristics were not influenced by the planting spacing nor by the clone types. The HT was influenced by the spacing with the highest value (26.3 m) verified in the spacing 3 m x 3 m. The db was influenced only by the clone types and the clones 3335 and 3487 presented the highest values (0.46 and 0.41 g.cm-3, respectively). The BS, BLB and BT were influenced only by clones with higher yields with clones 3335 and 3487. There were no significant interactions for any of the evaluated characteristics.

Soybean is the most commercially cultivated crop in Paraguay, and obtaining high yields requires the application of large amounts of fertilizers, raising the cost of production. Developing strategies for the efficient use of applied nutrients is necessary. Therefore, the study aimed to evaluate the agronomic efficiency of combinations of mineral fertilizers with organic matter and rock powder in the development, nutrition, and yield of soybean. The experiment was carried out in Hernandarias, Paraguay, in the 2016-2017 harvest. The different fertilizers influenced the absorption of Zn, Mg and K, and grain yield. Among the treatments, the highlight was the agronomic efficiency index obtained by the replacement of 30% of mineral fertilizer by humus, presenting grain yield of 3219, 67 kg ha-1. However, it was equal to the mixing 30% of humus + rock powder with 70% of NPK formulation 04:40:10 with grain yield of 3206.50 kg ha-1, and the mixing 20% of humus + rock powder with 80% of NPK formulation 04:40:10 with grain yield of 3165.17 kg ha-1. Thus, it is recommended to use rock powder and humus in soybean production in Paraguay, especially in Latossolos (Oxisols) that have little organic matter and low CTC.

The effect of aldicarb on mortality, motility, and reproduction of M. incognita in soybean was studied. The mortality of second-stage juveniles (J2) in aldicarb solution (5 and 50 μg mL-1) was only high at 20 days of exposure, being higher in the concentration of 50 μg mL-1 and lower in control (water). Motility was inversely proportional to the exposure time, and at 20 days of incubation, the number of J2 mobiles was statistically equal for both concentrations evaluated. There was a reduction inversely proportional to the number of galls and eggs per gram of root according to the J2 incubation time in water and aldicarb (5, 10, and 20 days). J2, when incubated in 50 μg mL-1 aldicarb for 5 and 10 days, always provided the same values regarding the number of galls and eggs per gram of root. The incubation for 20 days resulted in the loss of J2 infectivity, both in water and in aldicarb (5 and 50 μg mL-1), with practically no galls and eggs. When the J2 were incubated in the soil with the application of aldicarb solution (5 and 50 μg mL-1) or water (control), followed by soybean planting, 5, 10 and 20 days after, the J2 infectivity was null in the treatments with aldicarb (5 and 50 μg mL-1). However, when the J2-infested soil was sprayed with pure water (control), gall formation and reproduction decreased with the J2 incubation period, with a drastic reduction from the 5th day. Therefore, exposure to aldicarb affects the life cycle of M. incognita in soybeans.

Currently, some important hybrids have replaced traditional radish cultivars, without, however, developing necessary studies on the best planting density for different Brazilian conditions. Thus, the present study aimed to evaluate the effect of spacing between rows and plants on the development and yield of the ‘Margaret Queen’ radish hybrid. A randomized blocks experimental design with four replications in a 3 x 3 factorial scheme was used. Three row spacings (10, 15, and 20 cm) and three spacings between plants in the row (3, 6, and 9 cm) were evaluated. The seeds were sown in furrows at 1.0 cm deep, and the harvest was carried out at 28 days after sowing. The following were determined: number of leaves, root diameter, root length, average root weight, non-damaged root yield, damaged root yield, commercial root yield, and non-commercial root yield. The row spacing did not influence the development of the plants, but it affected the root yield. The row spacing of 20 cm had the lowest root yield. The spacings that provided the highest commercial root yield (D>30 mm) of the Margaret Queen radish hybrid were 10 and 15 cm between rows and 6 cm between plants. The 3 cm spacing between plants is the least suitable for the cultivation of the Margaret Queen radish hybrid radish under the studied conditions.

Conscious agricultural management, which aims to conserve natural resources, has been the target of contemporary agriculture. In this context, the reuse of water in deficit water depth in agricultural irrigation becomes a viable technique, and this work aimed to evaluate the effect of different irrigation depths with wastewater and soil mulching on the microbiological and postharvest characteristics of the Italian zucchini. The experiment was conducted in the field conditions with a randomized block design in a split-plot arrangement. Four irrigation depths (100%, 85%, 70%, and 55% of the estimated ETc from the Class A Evaporation Pan) and three types of soil mulching (rice husk, double-sided black and white polyethylene film, and uncovered soil) were analyzed. Texture, titratable acidity (TA), soluble solids content (ºBrix), pH, and the ºBrix:TA ratio of the Italian zucchini were analyzed, besides the microbiological analysis. The irrigation depth or soil mulching did not influence the pH of the Italian zucchini. The uncovered soil promoted higher titratable acidity to the Italian zucchini. The texture of the fruit, the soluble solids, and the ºBrix:TA ratio was influenced by the types of soil mulching and irrigation depths. The use of wastewater for drip irrigation reduces the effects of the microbial load on the crop.

Lettuce is considered the most produced and consumed leafy vegetable; however, it has short post-harvest life, which generates significant losses for both producers and consumers. Studies have proven the beneficial effect of silicon on fruits and vegetables. Therefore, the aim of the current study is to evaluate the influence of leaf calcium silicate application on the growth, biomass production and postharvest conservation of curly lettuce. The experiment was carried out in greenhouse at Federal Rural University of Amazonia, Parauapebas Campus / PA. It followed a completely randomized design (CRD) with five Si concentrations (0.0, 2.0, 4.0, 6.0 and 8.0 mg L-1) and eight repetitions, which totaled 40 plants. Plants were grown in plastic pots (capacity = 3 dm3) filled with soil classified as Red-Yellow Argisol. Different Si concentrations were applied to plant leaves, at the 20th and 27th days after transplantation (DAT). Silicon has favored the growth and development of lettuce plants, as well as reduced their post-harvest weight loss. It was possible concluding that the herein tested Si concentrations, which were applied to leaves - in the form of calcium silicate - had beneficial effect on lettuce plants.

One of the main problems faced in corn cultivation, especially in Cerrado regions, is the deficiency of micronutrients. Among the micronutrients essential for the development of plants, boron (B) stands out for participating in a series of physiological processes. Based on this, the present work aimed to evaluate the performance of corn under fertilization with different sources and doses of boron. The randomized block design in a 4x3 factorial scheme was used. Four boron doses (0, 1, 2, and 3 kg ha-1) and three nutrient sources (boric acid, borax, and ulexite), applied in topdressing, were evaluated. Plant height (cm), stem diameter (mm), first ear insertion height (m), ear length (cm), ear diameter (mm), number of rows per ear, number of grains per row, 1000-grain weight (g), and grain yield (kg ha-1) were evaluated. It was concluded that the boron sources and doses used did not influence the results of plant height, first ear insertion height, number of rows per ear, and grain yield. The three doses evaluated provided increases in stem diameter, with a dose of 2.08 kg ha-1 being the one with the highest average. The application of borax and ulexite results in higher values of ear diameter, number of grains per row, and 1000-grain weight. The dose of 1.74 kg ha-1 of boron provides the highest 1000-grain weight.

The objective was to evaluate the effect of calcium silicate on the chlorophyll content and gas exchange of two tomato hybrids. The design used was in randomized blocks in a 2x5 factorial scheme, with four replications. The first factor was composed of two tomato hybrids: Ivety and Natália, and the second factor was composed of five doses of calcium silicate (0, 150, 300, 450, and 600 kg ha-1), applied to the substrate before planting the seedlings. Gas exchange: net CO2 assimilation rate (A), leaf transpiration rate (E), stomatal conductance (gs), internal CO2 concentration (Ci), water-use efficiency (WUE), intrinsic efficiency water use (iWUE), and instant carboxylation efficiency (ACi); SPAD index and the levels of chlorophylls a, b, and total were evaluated. The analyzes were performed in the stages of first flowering (17 days after transplanting - DAT), full flowering (58 DAT), and full fruiting (78 DAT). At 17 DAT, no difference was observed for gas exchange variables and photosynthetic pigments. The application of calcium silicate reduced gas exchange and photosynthetic pigments at 58 DAT. The hybrid Natália had the highest A, WUE, iWUE, and ACi at 78 DAT. However, the hybrid Ivety in the same growth stage, in full fruiting, was superior only for the internal concentration of CO2 and SPAD index, with no difference for photosynthetic pigments.

The coffee plant can grow together with different plants, but the presence of allelochemicals can affect the crop post-planting. This study aimed to evaluate the early growth of coffee seedlings following treatment with plant extracts from different botanical families. The experimental design used randomized blocks with four trials, in a 7 × 2 factorial scheme; the first factor consisted of aqueous extracts from six species: canola, crotalaria, brachiaria, sunflower, wheat, and lupine; water was used as the control. The second factor comprised of different botanical parts of the aforementioned six species of plant. The extracts were diluted to 5% concentration and were applied at a dose of 20 mL per plant. The agronomic variables analyzed were plant height (PH), stem diameter (SD), leaf area index (LAI), leaf dry matter (LDM), root dry matter (RDM), and root length (RL). Compared to the canola extract, the application of brachiaria extract resulted in the best response in PH, regardless of the botanical part that constituted the extract, leading to an increase in PH by 3.77 cm. The agronomic character most sensitive to the application of aqueous extracts was PH, in which the brachiaria extract was prominent in inducing the greatest growth, whereas the canola extract hindered the initial development of Arabica coffee seedlings.

This research was conducted from 2017 to 2018 to produce genetic diversity and examine selected suitable hybrids concerning certain agricultural traits under normal and water-deficit stress conditions in a Zarghostar-Arta company. In 2017, four potato cultivars, namely, Luca, Banba, Esprit, and Agria, were crossed as parents via mutual hybridization based on the diallel method guided by Griffing’s method III. About 8550 true potato seeds were produced, among which 3944 seeds were germinated, and 151 hybrids were selected for culturing on a split-plot with a randomized complete block design involving three replications. The main factors of interest in the design were three irrigation levels (100%, 85%, and 70% water supply requirements), and the sub-factors were 12 populations. The highest specific combining ability for tuber yield was found in the direct cross of the ♂Luca×Esprit♀ compound under normal and mild conditions. In mild and severe stress conditions, the hybrid of ♀Luca×Agria♂ and the direct cross of the ♀Luca×Esprit♀ compound had the highest tuber yields. The general heritability of tuber yield ranged from 81.68% (in 70% available water) to 94.66% (in 100% available water), and the specific heritability ranged from 62.39% (in 85% available water) to 86.78% (in 100% available water). Additive variances in the varieties were 118.05, 46.92, and 37.49, and dominance variances were 33.82, 8.97, and 0.68 in 100%, 85%, and 70% available water, respectively.

This study aimed to evaluate the effect of the integrated crop-livestock system on the contents and stocks of total organic carbon, total nitrogen, and soil organic matter. The experiment was carried out between April 2016 and February 2017, in a randomized block design in a strip-block scheme, with additional control treatment (fallow) and four repetitions. The treatments consisted of two densities of oat sowing (40 and 60 kg ha-1) in strips A and different grazing frequencies (without grazing - WG, one grazing - 1G, and two grazing - 2G) in strips B, besides fallow as a control treatment. The determinations of the contents of total organic carbon (TOC), total nitrogen (TN), and organic matter (SOM) were carried out in the soil layers of 0-5, 5-10, and 10-20 cm. Samplings were carried out after oat management, in the winter, and after soybean harvest, in the summer. The sowing density of black oats and the grazing frequencies were not able to promote changes in the total organic carbon and in the TOC stock, regardless of the time of evaluation. The use of 40 kg ha-1 of oat seeds would be recommended, as it does not promote changes in the increase in MOS, thus generating savings in the acquisition of seeds. The use of the lowest density of oat without grazing and one grazing promoted changes on the total nitrogen in the 5-10 cm layer after the removal of oats, when compared to the fallow, and it presented content similar to the management with two grazings.

Livestock systems require a thorough analysis of zootechnical and financial indicators. In this sense, the objective of this study was to evaluate the bioeconomic performance of feedlot bulls with different genetic groups in 2012 and 2013. The experiment was carried out on a farm in Paragominas, State of Pará. The confined animals belonged to the Nellore (NE), ½ Angus ½ Nellore (AN) and ½ Charolais ½ Nellore (CH) breeds. The indicators analyzed were the cost of production and economic indicators. Additionally, zootechnical indicators were evaluated, being considered NE, AN, and CH as treatments in a completely randomized design. The financial results of the total production cost were R$ 118,493.21 in 2012, and R$ 111,166.35 in 2013, and the profitability obtained was 11% in 2012 and 8% in 2013. Regarding the zootechnical indicators, the CH genetic group showed superiority (P <0.01) compared to the NE genetic group for the variables initial weight (IW), final weight (FW), weight gain (WG), average daily weight gain (DWG), and carcass yield (CY). The confinement proved to be economically viable, with positive margins and satisfactory profitability, and the CH genetic group had the best indicators and the highest increase in the final revenue of the activity.

The main cause of decreased soil fertility and soil organic matter content is intensive crop farming with inadequate management. This study aimed to evaluate soil chemical properties, total organic carbon content, physical granulometric fractions (particulate organic carbon and mineral-associated organic carbon), carbon stocks, and carbon management indices of oxisols in different integrated agricultural production systems (IAPSs) with reference to values in a haymaking area and native forest. The experiments were performed using completely randomized design, considering nine differently managed areas, including seven IAPSs and two reference areas (haymaking area and native forest); four soil samples from the 0.00-0.05, 0.05-0.10, and 0.10-0.20 m layers were randomly collected from each area and the abovementioned variables were evaluated. The results showed no differences in variables between the managed and reference areas, indicating the maintenance of fertility and carbon fractions. Therefore, the tested management strategies promote beneficial modifications of soil properties. Producers should adopt different IAPS management strategies for soil preservation.

This study aimed to evaluate the formation of tamarind tree seedlings in different protected environments and substrates. Five protected environments were used and substrates using combinations of different proportions of humus, cattle manure, vermiculite, and cassava stems. The environments with screens and the environments with polyethylene films were conducive to the emergence of the tamarind seedlings. All the substrates presented adequate conditions for the emergence of seedlings in these environments. The environment covered with bacuri straw was not favorable to the emergence of the tamarind seedlings. The substrates containing cattle manure provided the best conditions for emergence in the environment covered with bacuri straw. The greenhouses and the screenhouse with the aluminized screen and the substrates containing manure provided the largest number of leaves, larger plants, and larger diameters. The mixture of cassava stems and cattle manure, as well as the mixture of three or four tested materials, are conducive to the development and accumulation of biomass in tamarind seedlings. The mixture of humus with vermiculite or cassava stems is not indicated for the biomass accumulation in tamarind seedlings. Greenhouses and screens are indicated for the formation of high-quality seedlings.

Salinity is one of the environmental stresses that most affects plants' vital processes, especially germination. Brassinosteroids, including 24-epibrassinolide (EBL), have multiple actions in essential processes in plants. Thus, this research's objective was to evaluate the effects of EBL on tomato seeds' physiological conditioning on germination, growth, and production of dry seedling mass under salinity conditions. The experiment was carried out in a 2x5 factorial scheme, as follows: two concentrations of EBL (0 and 10-6 M) and five levels of salinity (0.5 control; 1.5; 3.0; 4.5 and 6.0 dS m-1), consisting of ten treatments, with four replications of 50 seeds. In isolation, the salt stress reduced the percentage of germination and germination speed index from four to 14 days, besides all the plants' growth traits. In turn, the EBL increased the percentage of germination, germination speed index, seedling length, and radicle dry matter. The application of 10-6 M of EBL in seed immersion no effect on the seed germination of IPA 6 tomato cultivar under salt stress but increases the root length and the dry matter of the seedlings.

For the agricultural tractor's best performance, it must be correctly adapted to the job. Among other factors, the adequacy of tire inflation pressure is one of the most important and may influence the operation's efficiency and productivity. This study aimed to evaluate an agricultural tractor's operational performance with different tire inflation pressures in the subsoiling operation. The study was carried out in an experimental area of the Agricultural Machinery and Mechanization Laboratory of the experimental farm “Água Limpa,” belonging to the University of Brasília. The experimental design used was in randomized blocks with the following values, 206.8 kPa (30 psi), 137.9 kPa (20 psi), and 68.9 kPa (10 psi), of inflation pressure for agricultural tractor tires. The mechanized set used was a tractor model TM7020 2WD MFWD pulling a subsoiler with five shanks, SPCR model, in a Latossolo Vermelho-Amarelo. The higher inflation pressure resulted in greater slippage, advance, hourly fuel consumption, and lower speed and operational field capacity.