Projected changes in ultraviolet index and UV doses over the twenty-first century: impacts of ozone and aerosols from CMIP6.

This study evaluated the health-related weighted ultraviolet radiation (UVR) due to the total ozone content (TOC) and the aerosol optical depth (AOD) changes. Clear-sky Ultraviolet Index (UVI), daily doses, and exposure times for erythema induction (Dery and Tery) and vitamin D synthesis (DvitD and TvitD) were computed by a radiative transfer estimator. TOC and AOD data were provided by six Earth System Models (ESMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6). For projections, we consider four Shared Socioeconomic Pathways scenarios-SSPs (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5)-and two time-slices (near: 2041-2060 and far future: 2081-2100). UVR projections showed pronounced changes for the summer hemispheres in the far future. TOC increases in mid- and high latitudes of the Southern Hemisphere caused decreases in UVR at the summer solstice. However, projections did not indicate sun-safe exposure conditions in South America, Australia, and Southern Africa. On the contrary, exposure around solar noon from 10 to 20 min will still be sufficient to induce erythema in skin type III individuals throughout this century. In southern Argentina and Chile, the UVR insufficiency for vitamin D synthesis at solar noon in skin type III remains the same during this century at the winter solstice. In the Northern Hemisphere, UVI and Dery at the summer solstice should remain high (UVI ≥ 8; Dery ~ 7.0 kJ m-2) in highly populated locations. Above 45 °N, UVR levels cannot be enough to synthesize vitamin D in skin type III during the boreal winter. Our results show that climate change will affect human health through excess or lack of solar UVR availability.

Impacts of 1.5 °C and 2 °C global warming on Eucalyptus plantations in South America.

Even if the maximum global warming thresholds established by the Paris Agreement (1.5 and 2 °C relative to pre-industrial levels) are not exceeded, part of the climate system impacts resulting from this warming will be unavoidable. Forestry industries may be especially vulnerable, due to water shortages and the inability of growing certain forest species. An important part of the South American economy depends on the forestry sector (between 2 to ~7% of the Gross Domestic Product), mainly products derived from Eucalyptus, and so evaluating water availability considering the temperature thresholds established by the Paris Agreement will be fundamental. This study analyzed increased global average temperatures at 1.5 °C and 2 °C, and the impacts on water availability, using the Climatic Water Balance (CWB), and also studied possible impacts on Eucalyptus plantations in South America. Monthly temperature and precipitation data obtained from a set of simulations and projections of 26 General Circulation Models (GCMs) were used, in four Representative Concentration Pathway (RCP) scenarios. The CWB was calculated for three periods: i) the pre-industrial period (1861-1890), ii) the present period (1975-2005), and iii) the period when temperature projections are expected to reach global average increases of 1.5 °C and 2 °C. Due to changes in the CWB, with increases in actual evapotranspiration, water deficits, and a reduced water surplus, Eucalyptus plantations will be negatively affected and economically unfeasible for about 49.2% to 56.7% of all of South America, including a large part of the Amazon region, northern South America, midwestern and northeastern Brazil, western portions of Bolivia, Paraguay, central/northern Argentina, and northern Chile. Only some parts of South America, like the southern and southeastern regions of Brazil, Uruguay, southern Argentina and Chile, Andes Mountain Range, and northwestern South America, will not suffer water deficits, and Eucalyptus plantations will be less impacted in these regions. Large parts of South America will suffer from changes in water availability. The future of the forestry industry, and especially Eucalyptus plantations in these regions, will depend on urgent and effective adaptation measures.

Temperatura base e filocrono em duas cultivares de oliveira / Base temperature and phyllochron in two olive cultivars

O objetivo deste trabalho foi estimar a temperatura base para emissão de folhas e determinar o filocrono em duas cultivares de oliveira, 'Arbequina' e 'MGS ASC315', durante a fase de muda em condições de campo. Foi instalado um experimento na Fazenda Experimental da Empresa de Pesquisa Agropecuária de Minas Gerais, Maria da Fé, MG. Utilizou-se o delineamento inteiramente casualizado, em esquema fatorial 2x6, sendo duas cultivares e seis épocas de transplantio, com quinze repetições. A temperatura base (Tb) foi estimada usando a metodologia do menor valor do quadrado médio do erro (QME), e o filocrono foi obtido através do inverso do coeficiente angular da regressão linear entre o número de folhas emitidas e a soma térmica acumulada. A Tb estimada para a Arbequina foi de 10,5°C e 11°C para a MGS ASC315. O filocrono diferiu estatisticamente somente entre as cultivares, sendo menor para a 'Arbequina' (21,7°C dia-1 folha-1) quando comparada com a 'MGS ASC315' (41,6°C dia-1 folha-1).

The objective of this work was to estimate the base temperature for leaf appearance and the phyllochron for two cultivars of Olea europaea L. A field experiment was carried out in the experimental area of the Agricultural Research Corporation of Minas Gerais, Maria da Fé, MG. The experimental design was completely randomized with two cultivars and six planting dates. Base temperature (Tb) was estimated by the minimum mean square error (MSE) and the phyllochron was estimated by the inverse of the slope of regression between main stem leaf number and accumulated thermal time. The estimated base temperature was 10.5°C for Arbequina and 11°C for MGS ASC315. The phyllochron was statistically different only between cultivars, lower for 'Arbequina' (21.7°C day-1 leaf-1) compared to 'MGS ASC315' (41.6°C day-1 leaf-1).

Desenvolvimento vegetativo de duas cultivares de oliveira na fase de muda / Vegetative development of two olive cultivars in seedling phase

O desenvolvimento de plantas, influenciado pela temperatura do ar, pode ser estimado através do conceito de filocrono, definido como o intervalo de tempo entre o surgimento sucessivo de folhas em uma haste, sendo o tempo expresso em °C dia e o filocrono em °C dia folha-1. O objetivo deste estudo foi avaliar o desenvolvimento de duas cultivares de oliveira durante a fase de muda, em diferentes épocas de aclimatação, utilizando o conceito de filocrono. O experimento foi conduzido na Fazenda Experimental da Epamig, em Maria da Fé, sul de Minas Gerais, Brasil. O delineamento utilizado foi o inteiramente casualizado em esquema fatorial 2x5, com duas cultivares ('MGS ASC315' e 'Arbequina'), cinco épocas de aclimatação (maio, junho, julho, agosto e setembro de 2010) e 15 repetições. O filocrono foi estimado pelo inverso do coeficiente angular da regressão linear entre o número de folhas emitidas (NF) e a soma térmica acumulada (STa). O filocrono em 'MGS ASC315' foi de 14,7°C dia folha-1 (época 1), 31,7°C dia folha-1 (média das épocas 2, 3 e 4) e 60,2°C dia folha-1 (época 5). O filocrono em 'Arbequina' foi de 17,3°C dia folha-1 (média das cinco épocas de aclimatação, uma vez que não apresentou diferença significativa entre as épocas). Nas épocas de aclimatação 3, 4 e 5, houve diferença do filocrono entre as cultivares, sendo que o menor filocrono foi para a cultivar 'Arbequina'. Nas épocas 1 e 2, não houve diferenças significativas entre as cultivares.

Plants development, influenced by air temperature, can be estimated through the concept of phyllochron, defined as the time interval between the appearance of successive leaves on a stem, being the time expressed in °C day and the phyllochron in °C day leaf-1. The objective of this study was to evaluate the development of two olive cultivars during the seedling phase at different acclimation dates, using the concept of phyllochron. The experiment was carried in the experimental area of the Agricultural Research Corporation of Minas Gerais, Maria da Fé, south of Minas Gerais, Brazil. The experimental design was completely randomized with two cultivars (MGS 'ASC315' and 'Arbequina'), five acclimation date (May, June, July, August and September 2010) and 15 repetitions. The phyllochron was estimated by the inverse of the slope of the linear regression between leaves number (NF) and accumulated thermal time (STa). The phyllochron in 'MGS ASC315' was 14,7°C day leaf-1 (date 1), 31,7°C day leaf-1 (average of dates 2, 3 and 4) and 60,2°C day leaf-1(date 5). The phyllochron in 'Arbequina' was 17,3°C day leaf-1 (average of five acclimation dates, due not statistically difference among dates). In acclimation dates 3, 4 and 5, not statistically difference between cultivars, and the smallest phyllochron for 'Arbequina'. In acclimation dates 1 and 2, were not statistically different between cultivars.

Funções de distribuição de probabilidade decendial e mensal para a deficiência hídrica no solo / Probability distribution function ten-day and monthly for soil water deficit

A determinação das probabilidades de ocorrência de certos níveis de deficiência hídrica do solo (DHS) é fundamental para o planejamento agropecuário e a gestão ambiental. O objetivo deste trabalho foi determinar as funções de distribuição de probabilidades (fdp) que melhor caracterizam a distribuição dos valores de deficiência hídrica no solo. As DHSs decendiais e mensais foram determinadas por meio de balanço hídrico diário do solo para as diferentes capacidades de armazenamento de água disponível dos solos da região de abrangência da estação meteorológica de Santa Maria. Verificou-se que os valores mensais e decendiais de DHS se ajustam às funções de distribuição de probabilidades lognormal, gama, exponencial e Weibull. Utilizando-se as fdp selecionadas para cada período do ano, é possível determinar a probabilidade de ocorrência de qualquer valor de DHS para os solos da região de abrangência da estação meteorológica de Santa Maria.

The determination of the probability of occurring soil water deficit (DHS) is important for planning agricultural and livestock activities and for environment management. The objective of this study was to determine probability distribution function that fit soil water deficit distribution. Ten-day and monthly DHSs were estimated by calculating daily soil water balance assuming several storage water capacities of soils in the under the scope of the meteorological station of Santa Maria. Monthly and ten-day DHS fit to lognormal, gama, exponential and Weibull probability distribution functions. It is possible to determine the probability of occurring any DHS value at any time throughout the year in the central region of Rio Grande do Sul with the probability distribution functions selected in this study.

Risco de estresse térmico para o feijoeiro em Santa Maria, RS / Thermal stress risk for common bean in Santa Maria, RS, Brazil

A quantificação da disponibilidade térmica para os cultivos é importante no planejamento das atividades do agronegócio. O objetivo deste trabalho foi determinar as datas de semeadura com menor risco de ocorrência de altas temperaturas do ar, durante a floração do feijoeiro, e verificar se existe diferença entre grupos de hábito de crescimento de feijoeiro quanto à freqüência de ocorrência de temperaturas elevadas, para a região central do Rio Grande do Sul. Para tanto, foi determinada a freqüência de ocorrência de temperatura máxima diária do ar maior ou igual a 28, 30 e 32°C, durante o período mais crítico de sensibilidade do feijoeiro às altas temperaturas, que ocorre do aparecimento dos botões florais ao aparecimento dos primeiros legumes cheios, para três grupos de hábitos de crescimento de feijoeiro e dois períodos recomendados de semeadura (cultivo de safra e safrinha). Dentro de cada período recomendado, foram consideradas semeaduras a cada cinco dias, de 15 de agosto a 15 de novembro, para o cultivo de safra, e de 10 de janeiro até o final de fevereiro, para o cultivo de safrinha. O ciclo de cultivo foi simulado para cada ano dos dados da estação climatológica principal de Santa Maria, no período de 01 agosto de 1968 até 31 de julho de 2004. Não houve diferença significativa entre os grupos de hábito de crescimento para a probabilidade de ocorrência de temperaturas elevadas. Há menor risco de danos causados por altas temperaturas do ar quando a semeadura é realizada no início do período recomendado para o cultivo da safra e no final do período recomendado para o cultivo da safrinha.

Quantifying thermal conditions for crops is important for planning agribusiness activities. The purpose of this study was to determine sowing dates with smaller risk of high air temperatures during flowering of common bean and to verify if there are differences among maturation groups considering the occurrence frequency of elevated temperatures, in the Central Region of Rio Grande do Sul State. The occurrence frequency of daily maximum air temperatures greater than or equal to 28, 30 and 32°C was determined for the period from bud emission to beginning of grain formation for three maturation groups and for each sowing date. The crop cycle was simulated with data collected in a climatological station at Santa Maria, from August 1968 to July 2004. There was not significant difference among the maturation groups for frequency of occurrence of elevated temperatures. There is lower risk of damages caused by elevated air temperatures when sowing is performed early in the spring growing season and late in the autumn growing season.