Is cannabis use a significant exposition to nicotine?

Purpose: Young cannabis users are at increased risk for cigarette initiation and later progression to nicotine dependence. The present study assesses to which extent cannabis users are exposed to nicotine through mulling, a widespread process consisting of mixing tobacco to cannabis for its consumption. Methods: Data are issued from an ongoing observational study taking place in Switzerland. A total of 267 eligible participants (mean age 19 years, 46.4% males) completed an anonymous self-administered questionnaire on their tobacco and cannabis intake in the previous 5 days. They also provided a urine sample that was blindly analyzed for cotinine (a key metabolite of nicotine) using liquid-chromatography coupled mass-spectrometry. After the exclusion of cannabis users not having smoked at least one joint/blunt in which tobacco had been mixed (n _ 2), and participants reporting other sources of nicotine exposition than cigarettes or mulling (n _37), four groups were created: cannabis and cigarette abstainers (ABS, n_ 69), cannabis only smokers (CAS; n _ 33), cigarette only smokers (CIS; n _ 62); and cannabis and cigarette smokers (CCS, n _ 64). Cotinine measures of CAS were compared to those of ABS, CIS and CCS. All comparisons were performed using ANCOVA, controlling for age, gender, ethnicity, BMI and environmental exposure to cigarette smoke in the past month (at home, in school/at work, in social settings). The number of mixed joints/blunts smoked in the previous 5 days was additionally taken into account when comparing CAS to CCS. Cotinine values (ng/ml) are reported as means with 95% confidence interval (95% CI). Results: In the previous 5 days, CAS had smoked on average 10 mixed joints/blunts, CIS 30 cigarettes, and CCS 8 mixed joints/ blunts and 41 cigarettes. Cotinine levels of participants considerably differed between groups. The lowest measure was found among ABS (3.2 [0.5-5.9]), followed in growing order by CAS (294.6 [157.1-432.0]), CIS (362.8 [258.4-467.3]), and CCS (649.9 [500.7-799.2]). In the multivariate analysis, cotinine levels of CAS were significantly higher than those of ABS (p _.001), lower than those of CCS (p _ .003), but did not differ from levels of CIS (p _ .384). Conclusions: Our study reveals cannabis users to be significantly exposed to nicotine through mulling, even after controlling for several possible confounders such as environmental exposure to cigarette smoke. Utmost, mixing tobacco to Poster cannabis can result in a substantial nicotine exposition as cotinine levels from cannabis only smokers were as high as those of moderate cigarette smokers. Our findings also suggest that mulling is adding up to the already important nicotine exposition of cigarettes smokers. Because of the addictiveness of nicotine, mulling should be part of a comprehensive assessment of substance use among adolescents and young adults, especially when supporting their cannabis and cigarette quitting attempts. Sources of Support: This study was funded by the Public Health Service of the Canton de Vaud. Dr. BÊlanger's contribution was possible through grants from the Royal College of Physicians and Surgeons of Canada, the CHUQ/CMDP Foundation and the Laval University McLaughlin program, QuÊbec, Canada.

Frações de fósforo em solo adubado com fosfatos em diferentes modos de aplicação e cultivado com milho

O histórico de uso e o manejo da adubação influenciam a capacidade de suprimento de P pelo solo. Neste trabalho, foram avaliadas as frações de P num Argissolo Vermelho da região do Cerrado, adubado com fosfatos de reatividade distinta, em diferentes modos de aplicação e cultivado com milho durante três safras. A área, que já havia sido adubada em épocas passadas, estava coberta por braquiária. O delineamento experimental foi o de blocos casualizados com quatro repetições, num esquema fatorial 4 x 3 + 1, envolvendo quatro fontes de P, na quantidade de 180 kg ha-1 de P2O5 (superfosfato triplo, termofosfato magnesiano, fosfato natural reativo de Arad e fosfato natural de Araxá), três formas de aplicação (a lanço em área total no primeiro ano, localizada no sulco de plantio no primeiro ano e parcelada anualmente no sulco) e uma testemunha (sem P) como tratamento adicional. O P foi fornecido considerando-se os teores totais do nutriente nas fontes. Após três cultivos de milho, foram retiradas amostras de solo na profundidade de 0-20 cm para o fracionamento do P. A interação entre fontes e modos de aplicação de P interfere nas frações do nutriente no solo no final do cultivo de milho. De modo geral, o parcelamento da adubação condiciona maior teor do nutriente nas frações inorgânica (todas as fontes) e orgânica (fontes mais reativas). O fato de a área ter sido anteriormente adubada e ocupada por braquiária influenciou os efeitos dos tratamentos, pois a produção de milho foi relativamente elevada onde não houve aplicação de P. Houve evidências da participação de frações consideradas pouco lábeis no suprimento de P para o milho, em função da diminuição dessas frações no solo.

Does gender really matter in cathlab

Purpose: Results of some PCI clinical trials indicated more procedure related complications and worse clinical outcomes in women than men, but due to a lower representation of female patients this question still remains open. We aimed toinvestigate characteristics and early and late clinical outcomes in female patients as compared to male when treated in a real life setting with a new generation DES.Methods: Among 3069 consecutive patients treated with Nobori DES, and enrolled in NOBORI 2 study, 675 were female. The primary endpoint of the study is target lesion failure (TLF), a composite of cardiac death, MI and target lesion revascularization (TLR) at 12 months. Data are entered in an electronic database; all adverse events are adjudicated by an independent clinical event committee and independent corelabs analyse all angiograms.Results: Compared to male patients, female patients were significantly older (68±10 vs ± 63±11 years; p<0.001), had higher incidence of diabetes (37% vs 27%; p<0.001) and hypertension (75% vs 66%; p<0.001), but lower frequency of previous MI, PCI/CABG and smoking history. Lesion characteristics were similar in two genders, except for lesions located at bifurcation which were more frequent inmale patients (22% vs 15% inmale and female patients respectively; p<0.001). Majority of QCA assessed parameters were similar with the exception for RVD, post-procedure MLD in-segment and %DS in-stent which were significantly lower in female patients (p<0.05 for all). In table 1 results at 6 months follow-up are presented and at the time of presentation 1 year results will be available. Table 1. Clinical results at 6 months follow-up Male (n=2394) Female (n=675) P value Cardiac Death 12 (0.5%) 5 (0.7%) 0.5550 MI 5 (2.1%) 4 (1.3%) 0.5089 TLR rate 17 (0.7%) 13 (1.9%) 0.0124 TLF rate 44 (1.8%) 17 (2.5%) 0.2745 Stent Thrombosis 12 (0.5%) 6 (0.9%) 0.2548Conclusions: Results indicate that there are differences in the demographics and risk factors in female and male patient's population. The frequency of adverse events at 6 months is low in both populations, showing trend toward slightly higher rate in female patients, particularly for target lesion revascularization.

Carbono orgânico e nitrogênio total do solo e suas relações com os espaçamentos de plantio de cafeeiro

A densidade de plantio e o arranjo das plantas exercem influência sobre a produção de resíduos vegetais nos agroecossistemas cafeeiros. Esse aporte diferenciado de resíduos regula os teores de C e N do solo. Este trabalho objetivou avaliar os teores de C orgânico e de N total em um Latossolo Vermelho distrófico cultivado com cafeeiro com diversos espaçamentos de plantio. O experimento foi conduzido no período de 1992 a 2004 na Fazenda Experimental da EPAMIG, em Machado (MG). Os tratamentos avaliados consistiram da combinação de quatro espaçamentos entre linhas (2,0; 2,5; 3,0; e 3,5 m), três espaçamentos entre plantas (0,5; 0,75; e 1,0 m) e dois sistemas de manejo dos resíduos culturais (entrelinha - EL e projeção da copa - PC), totalizando 24 tratamentos, dispostos no campo em blocos ao acaso, em esquema fatorial 4 x 3 x 2, com três repetições. Foram avaliados os teores de C orgânico (CO) e de N total do solo (NT), além da relação CO/NT. Nas amostras de solo da EL, os teores de CO e NT foram maiores do que os da PC. O espaçamento de plantio influenciou os teores de CO, com os maiores valores, em geral, no espaçamento de 3,5 m entre as linhas de plantio, quando a distância entre plantas foi de 0,5 e 0,75 m, na profundidade de 0-0,05 m. O maior acúmulo de resíduos vegetais, o menor revolvimento do solo e, conseqüentemente, os maiores teores de matéria orgânica favorecem a ocorrência de maiores teores de CO e NT na EL. A retirada da mata e o cultivo do solo com cafeeiro por 11 anos resultou em decréscimo nos teores de CO de 26 % a 38 % na EL e na PC, respectivamente, e diminuição média de 25 % nos teores de NT.

Prevalence of obesity in children in north-east Italy.

This study was performed to analyse the prevalence of obesity in children living in six different areas of the north-east of Italy. The study included 1523 children (749 male, 774 female), divided into four age categories (4, 8, 10, 12 +/- 0.5 years of age, respectively). The physical characteristics of the children were measured by trained and standardized examiners. In accordance with the guidelines on the Italian Consensus Conference on Obesity (Rome, 4-6 June 1991), a child was defined as obese when his weight was higher than 120% of the weight predicted for height, as calculated from the Tanner's tables. On average, the prevalence of obesity was higher in males than in females (15.7% vs. 11%). The highest prevalence was seen in 10-year-old males (23.4%). The prevalence increased with age both in males (4 years = 3.6%, 8 years = 11.2%, 10 years = 23.4%, 12 years = 17.3%) and in females (4 years = 2%, 8 years = 13.3%, 10 years = 12.7%, 12 years = 11.9%). This tendency was maintained when calculating the obesity prevalence by other methods, such as BMI, triceps skinfold and fat mass, although the magnitude of the prevalence was different depending on the criteria used to define it. A consensus on more precise criteria to define obesity is needed for a better diagnosis of obesity in childhood and to allow a more reliable measurement and comparison of the prevalence of obesity among populations.

Cardiovascular risk factor profiles and their social gradient from adolescence to age 74 in a Swiss region.

BACKGROUND: Few European studies have investigated how cardiovascular risk factors (CRF) in adults relate to those observed in younger generations. OBJECTIVE: To explore this issue in a Swiss region using two population health surveys of 3636 adolescents ages 9-19 years and 3299 adults ages 25-74 years. METHODS: Age patterns of continuous CRF were estimated by robust locally weighted regression and those of high-risk groups were calculated using adult criteria with appropriate adjustment for children. RESULTS: Gender differences in height, weight, blood pressure, and HDL cholesterol observed in adults were found to emerge in adolescents. Overweight, affecting 10-12% of adolescents, was increasing steeply in young adults (three times among males and twice among females) in parallel with inactivity. Median age at smoking initiation was decreasing rapidly from 18 to 20 years in young adults to 15 in adolescents. A statistically significant social gradient in disfavor of the lower education level was observed for overweight in all age groups of women above 16 (odds ratios (ORs) 2.4 to 3.3, P < 0.01), for inactivity in adult males (ORs 1.6 to 2.0, P < 0.05), and for regular smoking in older adolescents (OR 1.9 for males, 2.7 for females, P < 0.005), but not for elevated blood pressure. CONCLUSION: Discontinuities in the cross-sectional age patterns of CRF indicated the emergence of a social gradient and the need for preventive actions against the early adoption of persistent unhealthy behaviors, to which low-educated girls and women are particularly exposed.

Effectiveness of fused magnesium potassium phosphate for marandu grass

The current high price of KCl and great dependence on importation to satisfy the Brazilian demand indicate the need for studies that evaluate the efficiency of other K sources, particularly those based on domestic raw material. For this purpose, a greenhouse experiment was conducted with samples of a sandy clay loam Typic Haplustox, in a completely randomized 4 x 3 x 2 factorial design: four K rates (0, 60, 120, and 180 mg kg-1), three sources (potassium chloride (KCl), fused magnesium potassium phosphate (FMPP) and a mixture of 70 % FMPP + 30 % KCl) and two particle sizes (100 and 60 mesh), with three replications. Potassium fertilization resulted in significant increases in shoot dry matter production and in K concentrations, both in soil and plants. The K source and particle size had no significant effect on the evaluated characteristics. Potassium critical levels in the soil and the shoots were 1.53 mmol c dm-3 and 19.1 g kg-1, respectively.

Decomposition and nutrient release of leguminous plants in coffee agroforestry systems

Leguminous plants used as green manure are an important nutrient source for coffee plantations, especially for soils with low nutrient levels. Field experiments were conducted in the Zona da Mata of Minas Gerais State, Brazil to evaluate the decomposition and nutrient release rates of four leguminous species used as green manures (Arachis pintoi, Calopogonium mucunoides, Stizolobium aterrimum and Stylosanthes guianensis) in a coffee agroforestry system under two different climate conditions. The initial N contents in plant residues varied from 25.7 to 37.0 g kg-1 and P from 2.4 to 3.0 g kg-1. The lignin/N, lignin/polyphenol and (lignin+polyphenol)/N ratios were low in all residues studied. Mass loss rates were highest in the first 15 days, when 25 % of the residues were decomposed. From 15 to 30 days, the decomposition rate decreased on both farms. On the farm in Pedra Dourada (PD), the decomposition constant k increased in the order C. mucunoides < S. aterrimum < S. guianensis < A. pintoi. On the farm in Araponga (ARA), there was no difference in the decomposition rate among leguminous plants. The N release rates varied from 0.0036 to 0.0096 d-1. Around 32 % of the total N content in the plant material was released in the first 15 days. In ARA, the N concentration in the S. aterrimum residues was always significantly higher than in the other residues. At the end of 360 days, the N released was 78 % in ARA and 89 % in PD of the initial content. Phosphorus was the most rapidly released nutrient (k values from 0.0165 to 0.0394 d-1). Residue decomposition and nutrient release did not correlate with initial residue chemistry and biochemistry, but differences in climatic conditions between the two study sites modified the decomposition rate constants.

Effect of grade on disease-free survival and overall survival in FIGO stage I adenocarcinoma of the endometrium.

OBJECTIVE: To analyse the effect of differentiation on disease-free survival (DFS) and overall survival (OS) in patients with stage I adenocarcinoma of the endometrium. PATIENTS AND METHODS: From 1979 to 1995, 350 patients with FIGO stage IA-IC with well (G1), moderately (G2) or poorly (G3) differentiated tumors were treated with surgery and high dose-rate brachytherapy with or without external radiation. Median age was 65 years (39-86 years). RESULTS: The 5-year DFS was 88+/-3% for the G1 tumors, 77+/-4% for the G2 tumors, and 67+/-7% for the G3 tumors (P=0.0049). With regard to the events contributing to DFS, the 5-year cumulative percentage of local relapse was 4.6% for the G1 tumors, 9.0% for the G2 tumors, and 4.6% (P=0.027) for the G3 tumors. Cumulative percentage of metastasis was 1.4, 6.3 and 7.2% (P<0.001), respectively, whereas percentages of death were 6.0, 7.9 and 20.7% (P<0.001). The 5-year OS was 91+/-3, 83+/-4 and 76+/-7%, respectively (P=0.0018). In terms of multivariate hazard ratios (HR), the relative differences between the three differentiation groups correspond to an increase of 77% of the risk of occurrence of either of the three events considered for the DFS (HR=1.77, 95% CI [0.94-3.33]), (P=0.078) for the G2 tumors and of 163% (HR=2.63, 95% CI [1.27-5.43]), (P=0.009) for the G3 tumors with respect to the G1 tumors. The estimated relative hazards for OS are, respectively, in line with those for DFS: HR=1.51 (P=0.282) for the G2 tumors; and HR=3.37 (P=0.003) for the G3 tumors. CONCLUSION: Patients with grade 1 tumors are those least exposed to either local relapse, metastasis, or death. In contrast patients with grade 2 tumors seem to be at higher risk of metastasis, whereas patients with grade 3 tumors appear at higher risk of death. Since we have looked at the first of three competing events (local relapse, metastasis and death), this suggests that patients with grade 3 tumors probably progress to death so fast that local relapse, if any, cannot be observed.

Persistência do efeito de intervenções mecânicas para a descompactação de solos sob plantio direto

A compactação tornou-se uma das principais causas de degradação do solo em áreas agrícolas, estando diretamente relacionada ao sistema de manejo do solo adotado e, muitas vezes, demandando práticas de descompactação para mitigar esse problema. Este trabalho objetivou avaliar a duração do efeito de intervenções mecânicas, como a aração e escarificação do solo associadas à ação de semeadora de plantio direto equipada com mecanismos rompedores de solo tipo discos e discos + facão, como práticas mitigadoras da compactação de um solo manejado sob o Sistema Plantio Direto (SPD), por meio da avaliação de atributos físicos do solo e do esforço de tração. O estudo foi realizado no município de Coxilha, na região Norte do Rio Grande do Sul, localizado nas coordenadas geográficas de 28°10'18,7" S e 52°22'39,89" O, sobre um Latossolo Vermelho, em experimento instalado no ano de 2001 em área com histórico de oito anos sob SPD. Nessa área foram realizadas intervenções mecânicas anuais, mediante a aração e escarificação do solo, anteriores à implantação da cultura de verão. Os tratamentos de manejo do solo constituíram- se da testemunha, com manutenção ininterrupta do SPD por 16 anos e por seis períodos de tempo de condução desse sistema (7,5; 6,5; 5,5; 4,5; 3,5; e 2,5 anos) após a escarificação ou aração, aplicados nas parcelas principais. Nas subparcelas foram aplicados dois tratamentos de dispositivo de aplicação do adubo no sulco de semeadura (discos duplos defasados e facão + discos). O delineamento experimental adotado foi de blocos completos casualizados com parcelas subdivididas e três repetições. Os resultados indicaram a existência de compactação na camada subsuperficial do solo, situada entre 7 e 15 cm, evidenciada por aumentos na densidade e redução na porosidade total e macroporosidade do solo em todos os tratamentos avaliados. Observou-se que a intervenção mecânica apresenta potencial efêmero para mitigar a compactação e melhorar a estrutura do solo, com duração de até dois anos e meio dos atributos porosidade total e macroporosidade após a escarificação, e a densidade do solo depois da aração. Nos demais atributos avaliados, tais benefícios deixaram de ser perceptíveis em período inferior a dois anos e meio após a intervenção mecânica, o que não provocou alterações na força exercida na barra de tração do trator agrícola, comparativamente à testemunha. Contudo, o mecanismo facão + discos de rompimento do solo na semeadora foi efetivo em alterar os atributos avaliados, aumentando a macroporosidade, diminuindo a microporosidade, a densidade do solo e o esforço de tração e auxiliando, assim, na mitigação da compactação do solo.

Off-pump transapical mitral valve-in-ring implantation.

OBJECTIVES: The study aimed to evaluate the feasibility of off-pump transapical mitral valve-in-ring implantation and to test the performance of a custom-made self-expandable stent valve, in comparison with the standard SAPIEN valve. METHODS: Acute experiments were performed in five pigs. Animals (mean weight 58.4 ± 7.3 kg) underwent mitral valve annuloplasties under cardiopulmonary bypass using 26-mm rings (SJM?). Then, a 30-mm custom-made self-expandable stent valve or a 23-mm balloon-expandable transcatheter heart valve (Edwards SAPIEN XT?) was deployed within the annuloplasty rings through a transatrial access and under direct vision. Subsequently, the stent valves were inserted transapically under fluoroscopic guidance and off pump. RESULTS: The procedural success of transatrial and transapical mitral valve-in-ring procedures was 100% (10 of 10). Mean transatrial and transapical procedure time was 2.0 ± 1.1 and 22.0 ± 5.7 min, respectively. Haemodynamic status during transapical implantation remained stable, and differences in data collected before and after the stent-valve deployment were not statistically significant. Mean mitral annulus diameter and mean mitral orifice area in the group of self-expandable stent valves were 2.60 ± 0.02 cm and 4.16 ± 0.48 cm(2), respectively, whereas in the SAPIEN group they were 1.95 ± 0.18 cm and 2.26 ± 0.20 cm(2), respectively. Trace or mild regurgitation was detected only in the self-expandable stent-valve group. Mean gradients were 4.1 ± 4.5 mmHg across the self-expandable stent valves and 1.0 ± 0 mmHg across the SAPIEN valves. Postmortem examination confirmed adequate positioning of the self-expandable valves and the SAPIEN valves within the annuloplasty ring. CONCLUSIONS: Off-pump transapical mitral valve-in-ring implantation is safe and feasible. Transapical access may represent the ideal option for valve-in-ring procedures in cases of recurrent mitral regurgitation after mitral valve repair, in high-risk patients. Owing to the supra-annular profile of the valve components, our custom-made nitinol stent valve provides nearer to normal functional area than the SAPIEN valve.

Concurrent or Sequential Adjuvant Hormonoradiotherapy after Conservative Surgery for Early-Stage Breast Cancer: Clinical Results of the CO-HO-RT Phase II Randomized Trial.

Purpose: Letrozole (LET) has recently been shown to be superior to tamoxifen for postmenopausal patients (pts). In addition, LET radiosensitizes breast cancer cells in vitro. We conducted a phase II randomized study to evaluate concurrent and sequential radiotherapy (RT)-LET in the adjuvant setting. We present here clinical results with a minimum follow-up of 24 months. Patients and Methods: Postmenopausal pts with early-stage breast cancer were randomized after conservative surgery to either: A) concurrent RT-LET (LET started 3 weeks before the first day of RT) or B) sequential RT-LET (LET started 3 weeks after the end of RT). Whole breast RT was delivered to a total dose of 50 Gy. A 10-16 Gy boost was allowed according to age and pathological prognostic factors. Pts were stratified by center, adjuvant chemotherapy, boost, and radiation-induced CD8 apoptosis (RILA). RILA was performed before RT as previously published (Ozsahin et al. Clin Cancer Res, 2005). An independent monitoring committee reviewed individual safety data. Skin toxicities were evaluated by two different clinicians at each medical visit (CTCAE v3.0). Lung CT-scan and functional pulmonary tests were performed regularly. DNA samples were screened for SNPs in candidate genes as recently published (Azria et al., Clin Cancer Res, 2008). Results: A total of 150 pts were randomized between 01/05 and 02/07. Median follow-up is 26 months (range, 3-40 months). No statistical differences were identified between the two arms in terms of mean age; initial TNM; median surgical bed volume; post surgical breast volume. Chemotherapy and RT boost were delivered in 19% and 38% of pts, respectively. Nodes received 50 Gy in 23% of patients without differences between both arms. During RT and within the first 6 weeks after RT, 10 patients (6.7%) presented grade 3 acute skin dermatitis during RT but no differences were observed between both arms (4 and 6 patients in arm A and B, respectively). At 26 month of follow-up, grade 2 and more radiation-induced subcutaneous fibrosis (RISCF) was present in 4 patients (3%) without any difference between arm A (n = 2) and B (n = 2), p=0.93. In both arms, all patients that presented a RICSF had a RILA lower than 16%. Sensitivity and specificity were 100% and 39%, respectively.No acute lung toxicities were observed and quality of life was good to excellent for all patients.SNPs analyses are still on-going (Pr Rosenstein, NY). Conclusion: Acute and early late grade 2 dermatitis were similar in both arms. The only factor that influenced RISCF was a low radiation-induced lymphocyte apoptosis yield. We confirmed prospectively the capacity of RILA for identifying hypersensitive patients to radiation. Indeed, patients with RILA superior to 16% did not present late effects to radiation and confirmed the first prospective trial we published in 2005 (Ozsahin et al., Clin Cancer Res).

Rendimento e conservação de cebola alterados pela dose e parcelamento de nitrogênio em cobertura

O rendimento e a conservação da cebola são influenciados pela disponibilidade de nitrogênio (N) no solo, o qual é requerido em grande quantidade. O presente trabalho objetivou avaliar o efeito de doses e do número de aplicações de N no estado nutricional das plantas, no rendimento e na conservação pós-colheita de bulbos de cebola. Foram realizados três experimentos, em campo, em Cambissolos catarinenses. Os tratamentos consistiram de uma combinação fatorial (4 x 3) envolvendo quatro doses de N (0, 50, 100 e 200 kg ha-1) e três modos de aplicação (aos 45, aos 45 e 75, e aos 30, 60 e 90 dias após o transplante). De cada dose, 25 % foram adicionados no plantio e o restante aplicado em uma ou dividido em duas ou três aplicações iguais. O transplante das mudas foi sempre realizado na segunda quinzena de julho, e a colheita foi efetuada aproximadamente 115 dias depois. O rendimento de bulbos aumentou de forma quadrática com o aumento da quantidade de N aplicada. A dose de N estimada que proporcionou a máxima produtividade econômica variou de 249 kg ha-1 em 2006/07, onde o solo era arenoso, a 116 e 142 kg ha-1 em 2008/09 e 2009/10, respectivamente, em solo mais argiloso. Os rendimentos máximos obtidos foram de 38, 46 e 30 t ha-1 em 2006/07, 2008/09 e 2009/10, respectivamente, e as doses de N correspondentes à máxima produtividade econômica promoveram incrementos de 42, 10 e 17 %, respectivamente, no tratamento sem N. O aumento do número de aplicações de N em cobertura, de uma para duas ou três, não alterou o rendimento e a conservação pós-colheita em nenhum ano. Em solos arenosos com baixo teor de matéria orgânica, é necessário aplicar maior quantidade de N para obter alto rendimento de cebola do que em solos argilosos com médios teores de matéria orgânica. A adição de N ao solo pode alterar negativamente a conservação dos bulbos em anos chuvosos.