Efeito de temperatura e molhamento foliar em Phoma tarda e mancha de phoma em mudas de cafeeiro

Phoma leaf spot is a major disease of coffee plants in regions with specific conditions of temperature and humidity. Despite the importance of environmental variables for disease progression, so far they have been poorly understood. Thus, we assessed the effect of different temperatures (15, 20, 25 and 30 oC) on mycelial growth, production and germination of conidia of Phoma tarda; and the same effect of temperature (15, 20, 25 and 30 oC) and leaf wetness duration (6, 12, 24, 36 and 48 hours) on fungal infection and severity of disease over time in coffee plants. Disease assessment was integrated in the area using the disease progress curve (AUDPC) and the infection processes were observed by scanning electron microscopy (SEM). The optimal temperatures for fungus growth, conidial production and germination in vitro were 22.9, 29.8, and 25.1 °C, respectively. Temperatures ranging from 15-20 °C significantly increased germ tube length and provided favorable conditions for pathogen infection through observation of early events such as cuticle separation from leaf tissue. The same temperature range combined with increasing leaf wetness periods, reached the highest value of the AUDPC of phoma leaf spot. Thus, it was found that both temperature and leaf wetness duration in the variables assessed and the difference in relation to temperature for in vitro growth and sporulation for in vivo tests were important.Mancha de Phoma é uma das principais doenças do cafeeiro em zonas com condições específicas de temperatura e umidade. Apesar da importância das variáveis ambientais para o progresso da doença, até agora essas têm sido mal compreendidas. Avaliou-neste estudo, o efeito de diferentes temperaturas (15, 20, 25 e 30 ºC) sobre o crescimento micelial, produção e germinação de conídios de Phoma tarda, e o efeito da temperatura (15, 20, 25 e 30 ºC) e da duração do período de molhamento (6, 12, 24, 36 e 48 horas) sobre a infecção fúngica e severidade da doença, ao longo do tempo em plantas de café. A avaliação da doença realizada através da área abaixo da curva de progresso da doença (AACPD) e os processos de infecção foram observados por microscopia eletrônica de varredura (MEV). As temperaturas ótimas para o crescimento de fungos, produção de conídios e germinação foram de 22,9, 29,8, 25,1 °C, respectivamente. Temperaturas variando entre 15-20 °C aumentaram, significativamente, o comprimento do tubo germinativo e proporcionaram condições favoráveis para a infecção pelo patógeno através da observação dos primeiros eventos, tais como a separação da cutícula do tecido foliar. A mesma faixa de temperatura combinada com períodos crescentes de molhamento foliar, no máximo, 48 horas, atingiu os maiores valores da AACPD da Mancha Phoma. Assim, verificou-se que, tanto a temperatura quanto a duração do molhamento para testes in vivo e a influência da temperatura para o crescimento e esporulação in vitro foram importantes

LAYERED DOUBLE HYDROXIDES: NANOMATERIALS FOR APPLICATIONS IN AGRICULTURE

The current research aims to introduce Layered Double Hydroxides (LDH) as nanomaterials to be used in agriculture, with particular reference to its use as storage and slow release matrix of nutrients and agrochemicals for plant growing. Structural characteristics, main properties, synthesis methods and characterization of LDH were covered in this study. Moreover, some literature data have been reported to demonstrate their potential for storage and slow release of nitrate, phosphate, agrochemicals, besides as being used as adsorbent for the wastewater treatment. This research aims to expand, in near future, the investigation field on these materials, with application in agriculture, increasing the interface between chemistry and agronomy

LAYERED DOUBLE HYDROXIDES: NANOMATERIALS FOR APPLICATIONS IN AGRICULTURE

The current research aims to introduce Layered Double Hydroxides (LDH) as nanomaterials to be used in agriculture, with particular reference to its use as storage and slow release matrix of nutrients and agrochemicals for plant growing. Structural characteristics, main properties, synthesis methods and characterization of LDH were covered in this study. Moreover, some literature data have been reported to demonstrate their potential for storage and slow release of nitrate, phosphate, agrochemicals, besides as being used as adsorbent for the wastewater treatment. This research aims to expand, in near future, the investigation field on these materials, with application in agriculture, increasing the interface between chemistry and agronomy