Permanent wilt point from two methods for different combinations of citrus rootstock / Ponto de murcha permanete a partir de dois métodos para diferentes combinações copa porta-enxerto de citros

Considering that water is extremely important in agricultural production, but with restricted availability in some Brazilian regions, this research sought to identify the water limit for the rootstocks: Cleóptra tangerine (Citrus reshni hort. Ex Tan), Volkamer lime (Citrus Volkameriano Pasquale), Citrandarin ‘indio (TSK X TRENG 256), Santa Cruz Rangpur lime (Citrus × limonia) and Sunki Tropical tangerine (Citrus sunki HORT. EX TAN) grafted orange ‘Pera (Citrus sinensis), obtained by two methods: the traditional method of determining the permanent wilting point described by SHANTZ & BRIGGS (1912) recovery of plants with saturated environment and by irrigating recovery method. The experimental design used was in a completely randomized design with four replications totaling 20 experimental plots. It was verified that the rootstocks Cravo Santa Cruz lemon and Volkamerian lemon were the most resistant in initial conditions of water restriction, evaluated by the method of BRIGGS & SHANTZ (1912), with recording of humidity of 0.0488 and 0.0489 respectively. Under more severe conditions of water restriction, determined by the irrigation method, Volkamerian lemon presented the highest resistance, with a humidity of 0.0371.(AU)

Considerando que a água é extremamente importante na produção agrícola, mas com restrita disponibilidade em algumas regiões brasileiras, é que esse trabalho buscou identificar o limite hídrico inferior para os porta-enxertos: tangerina Cleóptra (Citrus reshni hort. Ex Tan), limão Volkameriano (Citrus Volkameriano Pasquale), citrandarin ‘Indio -TSK X TRENG 256, limão Cravo Santa Cruz (Citrus × limonia) e tangerina Sunki Tropical (Citrus sunki HORT. EX TAN) enxertadas em laranja ‘Pêra (Citrus sinensis), obtidos por dois métodos: o método tradicional de determinação do ponto de murchamento permanente descrito por BRIGGS & SHANTZ (1912) com recuperação das plantas em ambiente saturado e o método de recuperação por rega. O delineamento experimental utilizado foi o inteiramente casualizado, com quatro repetições, totalizando 20 parcelas experimentais. Verificou-se que os porta-enxertos limão Cravo Santa Cruz e o limão Volkameriano foram os mais resistentes em condições iniciais de restrição hídrica, avaliado pelo método de BRIGGS & SHANTZ (1912), com registro das umidades de 0,0488 e 0,0489, respectivamente. Em condições mais severas de restrição hídrica, determinado pelo método de rega, o limão Volkameriano foi o que apresentou maior resistência, com a umidade de 0,0371.(AU)

High fire temperature changes soil aggregate stability in slash-and-burn agricultural systems

Fire is a key controlling factor in ecosystem dynamics worldwide, especially, in tropical areas under slash-and-burn agricultural systems. Farmers use fire as a tool to clean the land, and benefit from nutrient enrichment from ash-soil heating. However, fire can cause some detrimental effects on soil systems, such as organic carbon depletion, increased soil erodibility, and changes to aggregate stability. In this study, an experimental fire was applied to a plot of land following the local traditional practice of slash-and-burn. The fire temperature was monitored in the field, and its effect on soil aggregate stability was assessed. The fire temperature on soil surface was measured in four trenches, and it ranged from 355 to 660 ºC (average 484 ± 142 ºC). The fire temperature did not affect soil organic matter content. However, aggregate stability increased by 10 % in comparison to unburned soil. Moreover, the geometric mean diameter of burned soil was 20 % higher than that of unburned soil. In conclusion, high fire temperature changes soil aggregate stability in slash-and-burn agricultural systems.

High fire temperature changes soil aggregate stability in slash-and-burn agricultural systems

Fire is a key controlling factor in ecosystem dynamics worldwide, especially, in tropical areas under slash-and-burn agricultural systems. Farmers use fire as a tool to clean the land, and benefit from nutrient enrichment from ash-soil heating. However, fire can cause some detrimental effects on soil systems, such as organic carbon depletion, increased soil erodibility, and changes to aggregate stability. In this study, an experimental fire was applied to a plot of land following the local traditional practice of slash-and-burn. The fire temperature was monitored in the field, and its effect on soil aggregate stability was assessed. The fire temperature on soil surface was measured in four trenches, and it ranged from 355 to 660 ºC (average 484 ± 142 ºC). The fire temperature did not affect soil organic matter content. However, aggregate stability increased by 10 % in comparison to unburned soil. Moreover, the geometric mean diameter of burned soil was 20 % higher than that of unburned soil. In conclusion, high fire temperature changes soil aggregate stability in slash-and-burn agricultural systems.(AU)

INVESTIGAÇÃO DA EXCREÇÃO DE RNA DO VÍRUS DA HEPATITE E (HEV) EM BOVINOS LEITEIROS DO ESTADO DE MATO GROSSO, BRASIL

O vírus da Hepatite E (HEV) é a principal causa de hepatite em países em desenvolvimento e ocidentais, responsável por infectar mais de 20 milhões de pessoas, ocasionando aproximadamente 60 mil mortes por ano no mundo. A transmissão do HEV foi confirmada a partir de suínos, bovinos e camelos, para primatas humanos e não humanos; por esta razão, a agricultura tradicional envolvendo a criação de diversas espécies e a proximidade entre elas pode potencialmente expandir as fontes zoonóticas e contribuir com a alta prevalência de HEV. Recentemente, o material genético do HEV foi detectado em amostras de leite e fezes de vacas leiteiras nos continentes europeu, asiático e africano, sugerindo a possibilidade de infecção em humanos através da ingestão de leite contaminado com o vírus. Diante da provável transmissão zoonótica do vírus para humanos através do leite, pela prática comum de criação mista de animais e pela circulação do HEV em suínos no Estado de Mato Grosso, o objetivo deste estudo foi investigar a excreção do vírus em vacas leiteiras, a partir de amostras de fezes e leite, através da identificação da ORF1 e ORF2 do HEV por meio da técnica de transcrição reversa seguida de reação em cadeia da polimerase (RT-PCR). Neste estudo, 430 amostras de fezes e leite de bovinos leiteiros do Estado do Mato Grosso foram coletadas e avaliadas quanto à presença do HEV por meio de técnicas moleculares. Foram selecionados 14 municípios em quatro mesorregiões do Estado, sendo que 215 vacas leiteiras provenientes de 49 propriedades foram amostradas. As principais características dos rebanhos foram levantadas por meio de um questionário epidemiológico. As propriedades selecionadas apresentavam a criação de diferentes tipos de animais domésticos conjuntamente, como suínos (71,4%), equinos (61,2%), caprinos (4%), ovinos (18,3%), aves (51%), cães (32,6%) e gatos (8,1%). Embora estudos anteriores tenham demonstrado a circulação do HEV nos suínos em Mato Grosso, neste estudo não foi possível a amplificação das ORF1 e ORF2 nas amostras fecais e de leite dos bovinos avaliados e, apesar de alguns autores sugerirem que as criações mistas podem ser fator determinante para a infecção nos bovinos, não foi observado uma associação positiva desta prática com a excreção viral em bovinos da mesma propriedade. Neste sentido, este estudo representa a primeira investigação molecular da excreção de HEV em bovinos no Brasil e ressalta-se a importância da realização de estudos adicionais abrangentes envolvendo este agente viral para verificar a circulação do vírus em bovinos, assim como investigar a participação de outras espécies animais na epidemiologia desta virose.

Hepatitis E virus (HEV) is the leading cause of hepatitis in developing and Western countries, responsible for infecting more than 20 million people, causing approximately 60,000 deaths each year worldwide. HEV transmission has been confirmed from pigs, cows and camels to human and non-human primates; for this reason, traditional agriculture involving farming of several species and the proximity between them can potentially expand zoonotic sources and contribute to the high prevalence of HEV. Recently, HEV RNA was detected in samples of milk and faeces from dairy cows in Europe, Asia and Africa, suggesting the possibility of infection in humans through ingestion of milk contaminated with the virus. Given the probable zoonotic transmission of the virus to humans through milk, the common practice of mixed farming and the circulation of HEV in pigs in the state of Mato Grosso, the aim of this study was to investigate the excretion of the virus in faecal and milk samples from dairy cows, by means of the identification of ORF1 and ORF2 of HEV through the reverse transcription followed by polymerase chain reaction (RT-PCR) technique. In this study, 430 samples of feces and milk from dairy cows from the state of Mato Grosso were collected and evaluated for the presence of HEV using molecular techniques. Fourteen cities were selected from four mesoregions of the state, where 215 dairy cows from 49 properties were sampled. The main characteristics of the herds were obtained through an epidemiological questionnaire. The selected farms had the common practice of farming different domestic animals together, such as pigs (71.4%), horses (61.2%), goats (4%), sheep (18.3%), chickens (51%), dogs (32.6%), and cats (8.1%). Although previous studies have demonstrated that HEV circulates in swine in Mato Grosso, it was not possible to amplify ORF1 and ORF2 in the fecal and milk samples from the evaluated cattle and, despite some authors suggest that mixed farming may be a determining factor for infection in cattle, a positive association between this practice and viral excretion in cattle on the same property was not observed. In this sense, this study represents the first molecular investigation of HEV RNA excretion in cattle from Brazil and emphasizes the importance of conducting additional comprehensive studies involving this viral agent to verify the virus circulation in cattle, as well as to investigate the participation of other animal species in the epidemiology of this viral infection.