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Brasília, Brazil

Marouelli W.A.,Embrapa Hortalicas | Abdalla R.P.,Faculdade da Terra de Brasilia | Madeira N.R.,Embrapa Hortalicas | da Silva H.R.,Embrapa Hortalicas | de Oliveira A.S.,Federal University of Reconcavo da Bahia
Horticultura Brasileira | Year: 2010

The objective of the present study was to evaluate the effects of crop residue covers (0.0; 4.5; 9.0; 13.5 t ha-1 millet dry matter) on water use and production of onion cultivated in no-tillage planting system (NT) as compared to conventional tillage system (CT). The study was carried out at Embrapa Hortaliças, Brazil, under the typical Savanna biome. Irrigations were performed using a sprinkle irrigation system when soil-water tension reached between 25 and 30 kPa. The experimental design was randomized blocks with three replications. Total net water depth applied to NT treatment was 19% smaller than the CT treatment, however, water savings increased to 30% for the first 30 days following seedlings transplant. Crop biomass, bulb size and yield, and rate of rotten bulbs were not significantly affected by treatments. The water productivity index increased linearly with increasing crop residue in NT conditions. Water productivity index of NT treatments with crop residue was on average 30% higher than that in the CT system (8.13 kg m-3).

Teles R.F.,Faculdade da Terra de Brasilia | del Menezzi C.H.S.,University of Brasilia | de Souza M.R.,Laboratorio Of Produtos Florestais | de Souza F.,Institute Ciencias Agrarias
Cerne | Year: 2010

This work aims to assess the bending properties of glued laminated timber beams (glulam) manufactured with species louro-vermelho (Sextonia rubra). Laminations were nondestructively tested using the transverse vibration method (EMlam). Then 10 glulam beams were manufactured and tested in static bending according to ASTM D 198 standard, having modulus of elasticity (EM), modulus of rupture (fM), and bending moment (M) determined. The finished beams were also tested by the transverse vibration method (EMvt). It was noted that the EMvt value was only 2% lower than the EM value. Using laminations with a high modulus of elasticity did allow effective gain in stiffness. Therefore, results indicate that the transverse vibration method is a valid, reliable technique both for testing glulam laminations and for assessing stiffness in finished beams. Bending properties in glulam beams were influenced by the stiffness of constituent laminations.

Marouelli W.A.,Embrapa Hortalicas | Abdalla R.P.,Faculdade da Terra de Brasilia | Madeira N.R.,Embrapa Hortalicas | de Oliveira A.S.,Federal University of Reconcavo da Bahia | de Souza R.F.,Faculdade da Terra de Brasilia
Pesquisa Agropecuaria Brasileira | Year: 2010

The objective of this work was to assess the effect of no-tillage production system (PD) using different rates of crop residues on cabbage water use efficiency and yield. Four rates of corn crop residues (0.0, 4.5, 9.0, 13.5 Mg ha-1 of dry matter) were tested in a clayed Latossolo Vermelho (Rhodic Haplustox), using the conventional tillage system (PC) as control. A completely randomized block design, with three replications was used. Cabbage stand, yield, fresh matter mass, diameter, height, and head compactness were not significantly affected by treatments. The total water depth applied along the entire crop cycle in PD treatments was up to 13% smaller than the treatments without residues. Water savings during the 30 days following transplanting reached 28%. The water productivity index increased linearly with crop residue rates under PD conditions, and was up to 21% higher than in the PC treatment.

Lima M.F.,Embrapa Hortalicas Embrapa Vegetables | Inoue-Nagata A.K.,Embrapa Hortalicas Embrapa Vegetables | Reifschneider F.J.B.,Embrapa Hortalicas Embrapa Vegetables | Ferraz R.M.,University of Brasilia | And 2 more authors.
Acta Horticulturae | Year: 2011

Viruses are the main pathogens of hot peppers (Capsicum spp.) in Brazil, directly affecting yield and marketable fruit quality. Disease incidence related to natural infection by viruses was assessed in domesticated and semi-domesticated 'Malagueta' (Capsicum frutescens), 'Habanero' (Capsicum chinense) and 'Cumari' (Capsicum baccatum var. praetermissum) hot pepper accessions from Embrapa Vegetables Active Germplasm Bank, Brasília, Brazil. Seedlings were grown from treated seeds in the greenhouse and transferred to the field 30-45 days after sowing; trials were located in the vicinity of a naturally virus-infected pepper field. Sampling was performed after 60 days post transplanting when plants were 90-105 days old. A total of 482 plants was individually sampled, and tested for the presence of tospoviruses (Tomato spotted wilt virus - TSWV; Groundnut ringspot virus - GRSV; Tomato chlorotic spot virus - TCSV), potyviruses (Potato virus Y - PVY; Pepper yellow mosaic virus - PepYMV), and tobamovirus (Pepper mild mottle virus - PMMoV) by enzymelinked immunosorbent assay (DAS-ELISA), and for cucumovirus (Cucumber mosaic virus - CMV) by dot-ELISA. Based on results of serological tests, 67% out of 482 plants presented single or mixed infections. The proportion of positive samples ranged from 9.1% (TCSV; 44 plants) to 45% (PMMoV; 217). PVY, PepYMV, TSWV and GRSV were found in 34.2% (165 samples), 25.5% (123), 15.7% (75) and 13.3% (64) of the tested-samples, respectively. CMV was not detected. It is noteworthy that virus infection was also detected on plants of the semi-domesticated genotype 'Cumari'. These results indicate the importance of viral diseases to crop management, considering the lack of efficient virus management strategies and the scarce information available on virus incidence affecting the crop, as well. A better understanding of the epidemiology of viruses infecting hot peppers will contribute to the development of rational disease management to prevent virus outbreaks.

de Oliveira M.I.L.,State University Londrina | Brunet D.,CIRAD - Agricultural Research for Development | Mitja D.,CIRAD - Agricultural Research for Development | Cardoso W.S.,Faculdade da Terra de Brasilia | And 3 more authors.
Acta Scientiarum - Agronomy | Year: 2011

This study aimed to determine the number of termite epigeal nests and estimate the soil turning capacity of termites in cultivated pasture environments and in a native vegetation area. Surveys were conducted in four areas: three pasture areas and a Cerrado area, measuring 5 ha each. For each nest, the height, the perimeter and diameter at the base were measured. The volume of each mound was calculated. Turned soil was determined by randomly sampling 30 termite mounds in a pasture area for bulk density determinations. The mean number of termite mounds per ha was 408; the highest number of termite nests (672 per ha) was found in the 10-year-old pasture. In terms of termite mound density, there was no difference between the Cerrado, 3-year-old pasture, and 3-year-old intercropped pasture treatments. The total area occupied by termite nests ranged from 0.4 to 1.0%. The mean bulk density of the nest materials was 1.05 g cm-3. The total nests volume ranged from 4 to 11 m3 ha-1. The total mass of the soil turned by the termites ranged from 3.4 to 13.4 ton. ha-1.

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