Efeito alelopático de Libidibia ferrea Mart. sobre o vigor das sementes de feijão-caupi

The cowpea is one of the main crops of importance for the Northeast region, being cultivated in areas of the Caatinga, considering that it is necessary to study the interaction between agricultural crops and forest species in this biome. Therefore, the present study aimed to evaluate a possible allelopathic influence of dried leaves in the decomposition process of Libidibia ferrea Mart. on the development of caupi bean seedlings, cv. Canapu. The leaves of the forest species were collected in the morning and dried at 40 ºC for 24 hours in the greenhouse, then were manually fragmented and added to sand forming the substrate, the following proportions of dry leaves and sand were adopted: 1:0 (control); 1:1/2; 1:1 and 1:2 (v:v). The substrates were decomposed for 15, 30, 45 and 60 days, the control treatment without decomposition, so subsequently the seeds of cowpea were sown. The seedling height and root length, dry mass of the aerial part of the root system and total normal seedlings were evaluated. The entirely randomized 4x5 factor scheme was used (sand proportions: dry leaves x periods of decomposition). The period of 30 days of decomposition causes a reduction in the length of the aerial part, in the dry mass of the aerial part, in the root system and in the total of the seedlings, the increase in the proportions of dry ironwood leaves affects the dry mass of the aerial part and total of the seedlings. Therefore, the cultivation of caupi beans, cv. Canapu, and ironwood in an agroforestry system is not feasible.O feijão-caupi é uma das principais culturas de importância para a região Nordeste, sendo cultivada em áreas da Caatinga, considerando isso é necessário o estudo da interação entre culturas agrícolas e espécies florestais nesse Bioma. Logo, o presente trabalho teve como objetivo avaliar uma possível influência alelopática de folhas secas em processo de decomposição de Libidibia ferrea Mart. sobre o desenvolvimento de plântulas de feijãocaupi, cv. Canapu. As folhas da espécie florestal foram coletadas no horário a manhã, e secas à 40 ºC, durante 24 horas em estufa, em seguida foram manualmente fragmentadas e adicionadas em areia formando o substrato, adotou-se as seguinte proporções de folhas secas e areia: 1:0 (controle); 1:1/2; 1:1 e 1:2 (v:v). Os substratos ficaram decompondo por 15; 30; 45 e 60 dias, o tratamento controle sem decomposição, assim subsequentemente realizou-se a semeadura das sementes de feijão-caupi. Foi avaliado o comprimento da parte aérea e comprimento da raiz, massa seca da parte aérea, do sistema radicular e total de plântulas normais. Foi utilizado o delineamento inteiramente casualizado em esquema fatorial 4x5 (proporções de areia: folhas secas x períodos de decomposição). O período de 30 dias de decomposição ocasiona uma redução no comprimento da parte aérea, na massa seca da parte aérea, do sistema radicular e total das plântulas, o aumento das proporções de folhas secas de pau ferro afeta a massa seca da parte aérea e total de plântulas. Diante disso, o cultivo de feijão-caupi, cv. Canapu, e pau ferro em um sistema agroflorestal não é viável

Prevalence evolution of SARS-CoV-2 infection in the city of São Paulo, 2020–2021

OBJECTIVE To estimate the evolution of the prevalence of SARS-CoV-2 virus infection among residents aged 18 years or over in the municipality of São Paulo. METHODS This is a population-based household survey conducted every 15 days, between June and September 2020, and January and February 2021. In total, the study comprised 11 phases. The presence of antibodies against SARS-CoV-2 was identified in venous blood using a lateral flow test, Wondfo Biotech. In the last phase, the researchers combined it with an immunoenzymatic test, Euroimmun. The participants also answered a semi-structured questionnaire on sociodemographic and economic factors, and on social distancing measures. Prevalence estimates and the 95% confidence interval were estimated according to regions, Human Development Index, sex, age group, ethnicity, education, income, and variables associated with risk or prevention of infection. To compare the frequencies among the categories of each variable, the chi-square test with Rao-Scott correction was used, considering a significance level of 5%. RESULTS In total, 23,397 individuals were interviewed and had their samples collected. The estimated prevalence of antibodies against SARS-CoV-2 ranged from 9.7% (95%CI: 7.9–11.8%) to 25.0% (95%CI: 21.7–28.7). The prevalence of individuals with antibodies against the virus was higher among black and brown people, people with lower schooling and income, and among residents of regions with lower Human Development Index. The lowest prevalences were associated with recommended measures of disease protection. The proportion of asymptomatic infection was 45.1%. CONCLUSION The estimated prevalence of the infection was lower than the cumulative incidence variation, except for the last phase of the study. The differences in prevalence estimates observed among subpopulations showed social inequality as a risk of infection. The lower prevalence observed among those who could follow prevention measures reinforce the need to maintain social distancing measures as a way to prevent SARS-CoV-2 infection