Conidia sporulation of Pyricularia oryzae in segments of wheat plants under six different temperatures/Esporulacao de conidios de Pyricularia oryzae em segmentos de plantas de trigo sob seis diferentes temperaturas

• Published in: Ciência rural 2020-04, Vol.50 (4)
• Main Authors: Kovaleski, Marcos, Maciel, Joao Leodato Nunes, Santos, Gustavo Bilibio dos, da Silva, Alieze Nascimento, Deuner, Carolina Cardoso
• Format: Article
• Language: English
• ISSN: 0103-8478
• DOI: 10.1590/0103-8478cr20190573

Wheat blast is known for developing itself more intensely under relatively high temperature conditions but many aspects related to its epidemiology remain unknown. The objective of this research was to evaluate the sporulative capacity of Pyricularia oryzae Triticum (Pot), the causal agent of wheat blast, in tissues of wheat plants under different temperatures degrees. Wheat plants of the cultivar Anahuac 75, susceptible to blast, were inoculated in the stage of flowering with conidial suspensions ([10.sup.5] conidia/mL) of the Pot isolates Py 12.1.209 and Py 12.1.132. Seven days after the inoculation, plants were cut in the following segments: leaves, stems and rachis (with blast severity ranging from 40 to 60%). Groups of each one of the three plant segments with the lesions were disposed in Petri-dish moist chambers, that were submitted to six different temperature treatments (18, 21, 24, 27, 30 and 33 [degrees]C). The most appropriate model that related the conidia production with temperature was identified in the evaluations conducted with stems. The established equations allowed identifying that the highest production of conidia of Pot occurs between 24 and 27 [degrees]C. Key words: wheat blast, conidial production, severity, sporulative lesions. Sabe-se que a brusone do trigo ocorre preferencialmente em condicoes de temperaturas relativamente altas, porem muitos aspectos sobre a epidemiologia desta doenca ainda permanecem desconhecidos. O objetivo deste trabalho foi avaliar a capacidade esporulativa de Pyricularia oryzae Triticum (Pot) em tecidos de plantas de trigo sob diferentes temperaturas. Plantas de trigo do cultivar Anahuac 75, suscetivel a brusone, foram inoculadas no estadio do florescimento com suspensoes de conidios dos isolados Py 12.1.209 e Py 12.1.132 de Pot ([10.sup.5] conidios/mL). Sete dias apos a inoculacao, as plantas foram cortadas e separadas em tres tipos de segmentos: colmos, folhas e raquis (com severidade de brusone variando de 40 a 60%). Um grupo de cada desses tres tipos de segmentos de planta contendo lesoes foi disposto em camara umida. O material foi acondicionado em seis niveis de temperatura: 18, 21, 24, 27, 30 e 33 [degrees]C. O modelo mais apropriado que relacionou a producao de conidios com temperatura foi identificado nas avaliacoes feitas nas amostras de colmo. As equacoes estabelecidas permitiram identificar que a maior producao de conidios de Pot ocorreu entre as temperaturas de 24 e 27 [degrees]C. Palavras-cha