IMPACT OF TEMPERATURE INCREASE ON POWDERY MILDEW IN MELON

The increase in greenhouse gases (GHG) has caused an increase in atmospheric temperature. It is known that temperature is determinant for the occurrence of plant diseases. In this context, the objective of this study was to evaluate the influence of temperature on powdery mildew in detached leaves of different melon cultivars. Nine melon cultivars were used: Araguaia, Awton, Eldorado, Gladial, Gold, Hibix, Natal, Juazeiro and Sancho. Two experiments were carried out with detached leaves in incubators with control of temperature and photoperiod (12/12h). The first experiment was conducted to determine the optimum temperature (15, 20, 25, 30, 35 and 40 °C) for the development of the disease and, from this temperature, increments of 1.7, 2.6, 3.1 and 5 °C, corresponding to the IPCC scenarios, were evaluated. The leaves were inoculated with a suspension of conidia of Oidium sp., placed on trays and kept in incubators. It was found that air temperature influences both the incubation period and severity of the disease. The optimum range for the development of melon mildew was 20-25 °C, and the increase in air temperature reduces the severity of the disease and, from 30 °C, there is no appearance of symptoms. The incubation period of melon powdery mildew increases at temperatures of 15 °C and above 27.6 °C. Melon cultivars show different responses to temperature increases. However, all cultivars were susceptible to powdery mildew, with high severity at temperatures favorable to the development of the pathogen

Low Carbon Technologies for Agriculture in Dryland: Brazilian Experience

Anthropogenic activities have altered the atmospheric composition since the industrial era, especially with the increasing greenhouse gas emission due to fossil fuel combustion, cement production, and land-use change. The Brazilian semiarid, covering approximately 969.589 km2 with 21 million people, region has 1.6 million agricultural establishments and 95% are classified as family farms. The typical agricultural systems are characterized by high grazing density, slash and burn practices, and fruits and legumes by irrigated monocultures. Consequently, soil degradation occurs due unsustainable soil management, decreasing soil carbon stock, and the biodiversity. The soil carbon depletion is also associated with saline, water, and thermal stresses. Saline, water, and thermal stresses in dryland, the impact of the land-use change associated with climate change, and few technological resources available for use in agricultural systems are the main reasons responsible for low productivity in the Brazilian semiarid region. Low-cost agricultural practices can contribute to build healthy and sustainable agroecosystems: among these, the selection of plant species tolerant to saline, water, and thermal stresses, the use of rhizobial inoculants, adoption of no-tillage, sowing green manure, and adoption of technologies to stock water to improve its efficiency and productivity

Maternal environment on seed germination and viability in cowpea / Ambiente materno na germinação e viabilidade de sementes de feijão-caupi

 Seed quality is determined by the environmental conditions to which they were exposed during their formation. Thus, the objective of this study was to evaluate the seed viability and seedling formation of cowpea cultivars produced in a high-temperature environment. Seeds of the cowpea cultivars Carijó, Itaim and Tapahium produced in growth chambers under temperature regimes T°1: 20-26-33 °C and T°2: 24.8-30.8-37.8 °C were used. The experimental design was completely randomized, with four replicates of 25 seeds, placed to germinate at a temperature of 25 °C in B.O.D chambers. Increase in air temperature during seed production did not hamper germination percentage. However, the 4.8 °C increase in air temperature reduced the vigor of seeds of the cultivar Tapahium, resulting in an increase in the number of abnormal seedlings. Seeds of the cultivars Carijó and Itaim produced under temperature regime 24.8-30.8-37.8 °C showed higher performance

Evolução da mancha preta do amendoim nas principais regiões produtoras da Argentina e do Brasil frente às mudanças no clima

A ocorrência da mancha preta do amendoim está diretamente relacionada aos elementos climáticos. Desta maneira, mapas de distribuição geográfica e temporal baseados em dados do clima contribuem com informações sobre o comportamento de patossistemas frente às mudanças climáticas. O objetivo deste estudo foi avaliar a evolução da favorabilidade climática à ocorrência da mancha preta para as principais regiões produtoras de amendoim da Argentina e do Brasil em função das mudanças climáticas. Na elaboração dos mapas foram considerados os meses de janeiro a março e empregada a metodologia de análise integrada das projeções climáticas e do problema fitossanitário com suporte do geoprocessamento. Foram considerados o clima normal (1961-1990) e o clima futuro (2011-2040, 20412070 e 2071-2100). Tendo em conta as particularidades da doença nas áreas produtoras de cada país, diferentes regras em critérios de lógica matemática de SIG foram aplicadas para a Argentina e o Brasil, pois elas incorporam efeitos diversos da interação das características próprias do patógeno virulento, hospedeiro suscetível e características ambientais. Os cenários climáticos futuros apontam para o aumento da favorabilidade para a ocorrência da mancha preta do amendoim para as principais regiões produtoras da Argentina e do Brasil.The occurrence of peanut black spot is directly related to climatic elements. Thus, maps of geographic and temporal distribution based on climatic data contribute to information on the behavior of pathosystems in the face of climate change. The objective of this study was to evaluate the evolution of climate favorability to the occurrence of black spot for the main peanut producing regions of Argentina and Brazil due to climate change. The months from January to March were considered to the production of the maps and the methodology of integrated analysis of the climate projections and the phytosanitary problem supported by the geoprocessing was used. Normal climate (1961-1990) and future climate (2011-2040, 2041-2070 and 2071-2100) were considered. Taking into account the particularities of the disease in the producing areas of each country, different rules in criteria of mathematical logic of GIS were adopted for Argentina and Brazil as they incorporate the effect of the interaction of the virulent pathogen, susceptible host and environmental characteristics. Future climate scenarios point to an increase in the favorability of peanut black spot occurrence in the main producing areas of Argentina and Brazil.Instituto de Investigación Animal del Chaco SemiáridoFil: Bisonard, Eduardo Matias. Instituto Nacional de Tecnologia Agropecuaria (INTA). Instituto de Investigación Animal del Chaco Semiárido; ArgentinaFil: Hamada, Emília. Embrapa Meio Ambiente; BrasilFil: Angelotti, Francislene. Embrapa Semiárido; BrasilFil: Ribeiro do Valle Gonçalves, Renata. Universidade Estadual de Campinas. Centro de Pesquisas Meteorológicas e Climáticas Aplicadas a Agricultura; BrasilFil: Rago, Alejandro Mario. Instituto Nacional de Tecnologia Agropecuaria (INTA). Centro de Investigaciones Agropecuarias; Argentin

Mudanças climáticas e ocorrência do míldio da videira no Brasil

The objective of this work was to evaluate the potential impact of climate change on the occurrence of grapevine downy mildew in Brazil. Seedlings containing four to six leaves were sprayed with a sporangia suspension containing 105 sporangia per milliliter. After spraying, the seedlings were subjected to temperatures of 26, 28, 29.1, 30.4, and 31.8°C for 24 hours. The percentage of diseased leaf area and the latent period were evaluated. Maps of the geographic and temporal distribution of the disease were made considering the monthly average of the mean air temperature and leaf wetness duration for the reference climate or climate normal (1961–1990) and the future climates (2011–2040, 2041–2070, and 2071–2100), considering the A2 and B1 gas emission scenarios, designed by the Intergovernamental Panel on Climate Change (IPCC). Favorability ranges were set and used in logic functions of the geografical  information system (GIS) to generate monthly maps for grapevine downy mildew. Rising temperatures interfered with the grapevine downy mildew infections, reduced the disease severity, and increased the latent period. Future climate scenarios indicate a reduction of favorability of downy mildew in Brazil, with variability in the different grape producing regions.O objetivo deste trabalho foi avaliar o potencial impacto das mudanças climáticas na ocorrência do míldio da videira no Brasil. Mudas com quatro a seis folhas foram pulverizadas com uma suspensão de esporângios de 105 esporângios por mililitro. Após a pulverização, as mudas foram submetidas às temperaturas de 26, 28, 29,1, 30,4 e 31,8°C, por 24 horas. Avaliaram-se a percentagem da área foliar doente e o período latente. Elaboraram-se mapas de distribuição geográfica e temporal da doença com as médias mensais da temperatura média do ar e da duração de período de molhamento foliar do clima de referência ou normal climatológica (1961–1990) e climas futuros (2011–2040, 2041–2070 e 2071–2100), nos cenários de emissão de gases B1 e A2, projetados pelo Painel Intergovernamental sobre Mudanças Climáticas (IPCC). Foram estabelecidas faixas de favorabilidade, utilizadas nas funções lógicas no sistema de informações geográficas (SIG) para a geração de mapas mensais para o míldio. O aumento da temperatura interferiu na infecção do míldio da videira, diminuiu a severidade da doença e aumentou o período latente. Os cenários climáticos futuros são indicativos de redução da favorabilidade do míldio no território brasileiro, com variabilidade para as diferentes regiões produtoras de uva

Genetic resistance of grape genotypes to rust

O objetivo deste trabalho foi avaliar a resistência à ferrugem causada pelo fungo Phakopsora euvitis, em genótipos de videira, e a efi ciência da infecção de acordo com a idade das folhas e concentração de inóculo. A avaliação foi feita em 15 genótipos, com base nos seguintes componentes de resistência: número de pústulas(urédios) por cm2; tamanho das pústulas; número de esporos produzidos por pústula; e período latente. Os componentes de resistência, com exceção do período latente, apresentaram grande variação quantitativa. A análise multivariada desses componentes diferenciou cinco grupos de genótipos. Os genótipos mais resistentes foram as cultivares porta-enxertos IAC313, IAC572 e IAC766, em que a efi ciência da infecção foi baixa, com pústulas menores e menor produção de urediniósporos, além de reação de hipersensibilidade no tecido em torno das pústulas. O grau de infecção aumenta com o aumento na concentração do inóculo. A ferrugem coloniza, indiscriminadamente, folhas jovens e folhas maduras de videira.The objective of this work was to evaluate the genetic resistance of grape genotypes to rust, caused by the fungus Phakopsora euvitis, and the infection effi ciency in relation to leaf age and inoculum concentration. The evaluation was carried out on 15 genotypes, based on the following resistance components: number of pustules (uredia) per cm2, size of pustules; number of urediniospores produced per pustules; and latent period. The resistance components, except for the latent period, presented considerable quantitative variation. The multivariate analysis of resistance components discriminated fi ve groups of genotypes. The more resistant genotypes were the rootstocks cultivars IAC313, IAC572, and IAC766, in which the infection effi ciency waslow, with small pustule sizes, and less urediniospores production, besides hypersensivity response on tissue surrounding the pustules. The infection increases with increasing of inoculum concentration. The rust colonizes young and mature grape leaves

Emergência e crescimento inicial de Amburana cearensis sob aumento da temperatura e dióxido de carbono

A concentração de dióxido de carbono [CO2] na atmosfera tem aumentado nos últimos anos, como consequência poderá causar efeitos diretos e indiretos nos agroecossistemas, e um dos biomas que mais sofrerá com esta mudança será a Caatinga. A Amburana cearensis é uma espécie nativa desse bioma e muito utilizada para fins medicinais, madeireiro, ornamental e forrageiro. Diante disso, objetivou-se com este trabalho avaliar o efeito do aumento da [CO2] sobre a emergência e crescimento inicial de plântulas de A. cearensis. O experimento foi conduzido em câmaras de crescimento, tipo Fitotron, com controle de temperatura, [CO2], umidade e fotoperíodo. As sementes foram semeadas em tubetes contendo substrato comercial e submetidas a dois regimes de temperatura (18-24-30 °C e 22-28-34 °C) e duas [CO2] (390 e 770 ppm), durante 56 dias. Foram avaliados porcentagem de emergência, tempo médio de emergência, velocidade média de emergência, índice de velocidade de emergência, número de folhas, diâmetro do colo, índice relativo de clorofila, comprimento, peso fresco e seco total das plântulas. Quando avaliados de maneira isolada, a temperatura e a concentração de CO2 apresentaram influência sobre o peso fresco total das plântulas de A. cearensis. A interação entre temperatura e [CO2] não influenciou na emergência de plântulas. No crescimento inicial de plântulas apenas as variáveis diâmetro do colo e peso seco foram influenciadas por esta interaçã

Rainfall events, high CO2 concentration and germination seeds of Caatinga

In semi-arid environments, the distribution of rainfall over time is decisive in emergence in a soil seed bank. The objective of this work was to evaluate the effect of rainfall events on the soil seed bank emergence of Caatinga species under high CO2 concentration. The experiment was carried out in an experimental area of Embrapa Semi-arid in a randomized complete block design, with subdivided plots. Each plot consisted of different environmental conditions (open top greenhouse with injection of 550 ppm CO2; open top greenhouse and environmental CO2; natural environment). The subplots consisted of the depth at which the seeds of Poincianella pyramidalis and Myracrodruon urundeuva were sown (superficially and buried at 0.02 m and 0.06 m depth). Seedling emergence was monitored daily after the first rains. During the experiment, weather data showed a rainfall volume of 83 mm, an average air temperature of 28.7 oC, average soil temperature of 35.4 e 34.9 oC, at depths of 0.02 and 0.06 m, respectively. Seedling emergence started 56 days after sowing and 4 days after the first rains. After 154 days of the start of the experiment, drip irrigation was performed. The greenhouse environment, regardless of the addition of CO2 or not, allowed higher emergence percentage of P. pyramidalis. The seeds of this species sowed on the soil surface only emerged when irrigation started. M. urundeuva seeds showed low germination even after irrigation

Initial growth of cowpea cultivars with an increase of 4.8 ° C in air temperature / Crescimento inicial de cultivares de feijão-caupi com aumento de 4,8 ° C na temperatura do ar

Vigorous germination and uniform seedling establishment are determinant and dependent on the performance of cultivars in the face of rising air temperatures. Thus, the objective was to evaluate the initial development of different cultivars of cowpea against the increase of 4.8 ° C in the daily temperature regime. The experiment was carried out in growth chambers, in a 5x2 factorial scheme (cultivars x temperature regimes). It was evaluated: germination percentage, germination speed index, average germination time, average germination speed, average germination speed, the initial seedling length and the initial seedling dry weight. The increase of 4.8 ° C in the temperature did not affect the germination percentage of the seeds, being above 90%. The germination speed index and the average germination speed were higher at temperatures of 24.8-30.8-37.8 ° C. For the germination percentage, the cultivars Pujante, Rouxinol and Tapahium presented the highest indexes, above 90%. The germination speed index and the average germination speed were higher for cv. For Rouxinol, consequently, the average germination time was shorter. The initial seedling length did not differ between cultivars, with an average value of 17.73 cm. The cv. Pujante differed among the other cultivars in terms of seedling dry mass. The initial growth and dry mass of seedlings were higher in the environment with a temperature of 24.8-30.8-37.8 ° C The 4.8 ° C increase in air temperature does not affect the initial phase of cowpea. The germinative parameters of this legume vary according to the cultivars