Influência da temperatura e da luminosidade no desenvolvimento de Guignardia citricarpa, agente causal da mancha preta dos frutos cítricos
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Data
2003-10-01
Autores
Timossi, Adriano J. [UNESP]
Goes, Antonio de [UNESP]
Kupper, Katia C.
Baldassari, Ricardo Braga [UNESP]
Reis, Renato F. dos [UNESP]
Título da Revista
ISSN da Revista
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Editor
Sociedade Brasileira de Fitopatologia
Resumo
O presente trabalho teve como objetivo avaliar sob condições de laboratório, o efeito de temperatura (15, 18, 20, 21, 24, 25, 27, 30, 33 e 35 ± 1 ºC) nas condições escuro, luz contínua e fotoperíodo 12/12 h, na produção de pseudotécios de isolados de Guignardia citricarpa, provenientes de regiões cítricolas dos Estados de São Paulo e Rio de Janeiro. Discos de folhas de limoeiro 'Cravo' (Citrus limonia), de 12 mm de diâmetro, foram autoclavados e depositadas (parte abaxial) na superfície do meio de cultura constituído por ágar-água 2%. Foram colocados quatro discos de folhas por placa onde, de forma conjunta e intercalar aos mesmos, depositaram-se dois discos obtidos de colônias de Phyllosticta citricarpa, com 21 dias de incubação. Foi, também, estudado o efeito da temperatura e do tempo de incubação (2, 8 e 16 h) na germinação dos ascósporos. Após 21 dias de incubação, a ótima temperatura ajustada pela função beta generalizada, para produção de pseudotécios deu-se a 26 e 22,5 a 27,5 °C, sob condição de escuro e de luz, respectivamente. Observou-se também produção de pseudotécios a 27 ºC em fotoperíodo 12/12 h. em estudo complementar foi verificado que, aos 19 dias, a 27 ºC, cerca de 90% dos pseudotécios haviam alcançado a maturidade, com abundante produção de ascósporos. A maior porcentagem de ascósporos germinados foi constatada na temperatura de 24 ºC, após 16 h de incubação. Dentre as vantagens alcançadas, incluem-se a possibilidade (i) da produção massal de ascósporos em curto período de tempo, e (ii) da padronização do inóculo, tanto qualitativa, quanto quantitativa.
Four experiments were carried out at the FCAV-UNESP-Campus of Jaboticabal to evaluate the effect of temperature (15, 18, 20, 21, 24, 25, 27, 30, 33 e 35 + 1 ºC), and three light regimes (dark, continuous light and a 12/12 hour photoperiod) on the production of Guignardia citricarpa pseudothecia in citrus (Citrus sp.) areas of the States of São Paulo and Rio de Janeiro. In addition, the effects of those temperatures and periods of incubation (2, 8 and 16 h) on ascospore germination were also studied. Disks of Rangpur lime (Citrus limonia) leaves measuring 12 mm in diameter were autoclaved and transferred to Petri dishes containing 2% water-agar with the abaxial surface facing the medium. Four disks were placed in each plate equally spaced from each other. Two disks from colonies of Phyllostica citricarpa with 21 days of incubation were deposited in the center of each plate and incubated at the different temperatures. The effect of temperature on the photoperiod of 12/12 in the germination of ascospore of G. citricarpa was also evaluated. The generalized beta function was at 26, 22.5 and 27.5 ºC for conditions of darkness and light respectively. Pseudothecium production was observed in the photoperiod of 12/12 h. Mature ascospores were observed after 14 days of incubation, at 27 ºC. The highest percentage of germinated ascospores was obtained at temperatures around 24 ºC, after 16 h of incubation.
Four experiments were carried out at the FCAV-UNESP-Campus of Jaboticabal to evaluate the effect of temperature (15, 18, 20, 21, 24, 25, 27, 30, 33 e 35 + 1 ºC), and three light regimes (dark, continuous light and a 12/12 hour photoperiod) on the production of Guignardia citricarpa pseudothecia in citrus (Citrus sp.) areas of the States of São Paulo and Rio de Janeiro. In addition, the effects of those temperatures and periods of incubation (2, 8 and 16 h) on ascospore germination were also studied. Disks of Rangpur lime (Citrus limonia) leaves measuring 12 mm in diameter were autoclaved and transferred to Petri dishes containing 2% water-agar with the abaxial surface facing the medium. Four disks were placed in each plate equally spaced from each other. Two disks from colonies of Phyllostica citricarpa with 21 days of incubation were deposited in the center of each plate and incubated at the different temperatures. The effect of temperature on the photoperiod of 12/12 in the germination of ascospore of G. citricarpa was also evaluated. The generalized beta function was at 26, 22.5 and 27.5 ºC for conditions of darkness and light respectively. Pseudothecium production was observed in the photoperiod of 12/12 h. Mature ascospores were observed after 14 days of incubation, at 27 ºC. The highest percentage of germinated ascospores was obtained at temperatures around 24 ºC, after 16 h of incubation.
Descrição
Palavras-chave
Citrus sinensis, Phyllosticta citricarpa, pseudotécios
Como citar
Fitopatologia Brasileira. Sociedade Brasileira de Fitopatologia, v. 28, n. 5, p. 489-494, 2003.