Germinação de uredósporos de Puccinia kuehnii submetidos a diferentes temperaturas e tempos de incubação

Abstract

A fe r r u ge m a la r a n ja d a , c a u sa d a p or Pu c c i n i a k u e h n i i é a tu almente u ma da s doenças ma is importantes da cana-de-açúcar, Palavras-chave adicionais: Epidemiologia, incubação, condições ambientais. n a s t em pe ra tu ra s: 1 0 , 1 5 , 2 0 , 2 5 e 3 0°C , em sei s pe rí od os d e incu ba çã o: 1 , 3, 6 , 1 2 , 1 8 , 2 4 hora s, tota liza ndo 3 0 tra ta mentos c o m 5 re p etições. Ao fina l de ca da período, a germina çã o foi interrompida adicionando-se 0 ,1 ml de lactofenol. Dividiu-se cada placa em qu atro campos e a valiou-se em cada u m, 50 esporos. Os dados de porcentagem de germinação foram submetidos à análise de variância em esquema fatorial 5x6 com desdobramento da interação em polinômios ortogona is. Pelo a ju ste de modelo ma temá tico, a germinação máxima ocorreu para o período de 12h e à temperatura de 21°C (R 2 =82%). Para os períodos de incubação, o modelo estimou qu e na cu rva de tempera tu ra 2 0°C, fora m necessá ria s 1 4 hora s (R 2 =65%) para se atingir a germinação máxima.Keywords: Epidemiology, incubation, environmental conditions. ABSTRACTT he ora nge ru st ca used by Puc cinia k ue hn ii, is currently one of the most importa nt disea ses of su garca ne du e to the potentia l da ma ge to su scep tible va rieties. T his stu dy eva l u a ted the effect of tempera ture on germina tion of u redospores. Uredospores were collected in the commercial field of suga rcane, variety SP 8911 15 in the city of Andirá (PR). After being removed from lea ves, the u redospo res u nderwent sepa ra tion of imp u rities a nd pla ced in a solu tion of distilled water with Tween-20 . T he spores suspension was calibrated using a Neubauer chamber and pla ted an aliquot of 0.1 ml on the a gar-water (1.5%). The plates were placed in BOD, a t t em p er a tu r es: 1 0 , 1 5 , 2 0 , 2 5 a n d 3 0 ° C i n si x i nc u ba t io n Minchio, C. A.; Canteri, M.G.; Rocha, J.A. Germination of uredospores of Puccinia kuehnii subjected to different temperatures and incubation times. Summa Phytopathologica, v.37, n.4, p.211-214, 2011. pe riod s: 1 , 3 , 6 , 1 2 , 1 8 , 2 4 hou rs, tot a li ng 3 0 tr ea t ment s wi th fiv e re p l ic a t io n s. At t h e e n d o f e a ch p er i o d, ge r m in a t io n wa s stopped by adding 0 .1 ml of lactophenol. Each pla te wa s divided into four fields and 50 spores were assessed in each field. Data on germina tion percentage were subjected to a nalysis of variance in a fa ct ori a l 5 x6 wit h th e u nfol din g of in tera cti on in o rth ogon a l polynomia ls. By a djustment of ma thema tical model, the maximum germ ina tion occu r red for the pe riod of 1 2 h a t a tem pera tu r e of 21°C (R2 = 82%). For the incubation periods, the model estimated that in the curve of tempera ture 20°C were requ ired 14 hou rs (R2 = 6 5 %) to rea ch maximu m germina tion.A ferrugem alaranjada da cana-de-açúcar, cujo agente etiológico é o fungo Puccinia kuehnii (W. Krüger) E.J. Butler, é uma doença que está presente em diversas partes do mundo (5,12,14,16), sendo que o seu pr...

Reaction of sugarcane varieties to orange rust (Puccinia kuehnii) and methods for rapid identification of resistant genotypes

“…The first symptoms observed in the susceptible varieties were chlorotic spots 15 days after inoculation; at 18 days the first pustules sporulated. Minchio et al (2011), working with temperatures of 10-30°C, observed a lower spore germination at 10°C. In our study, during the first 15 days after inoculation, temperatures below 10°C were recorded in 10 separate days (8 days in a row -from 8 to 15 days after inoculation) and the highest temperature did not surpass 20°C from 7 to 10 days after inoculation (Fig.…”

“…The spores were kept in the dark and at room temperature for 12 h. Spore viability was tested in four Petri dishes on 2 % water agar medium. The Petri dishes were divided into four fields; 50 spores per field were counted on a light microscope, i. e, 200 spores per Petri dish (Minchio et al 2011). Spores with a germination tube longer than their diameter were considered germinated.…”

“…Inoculation was carried out on 60-day-old plants using a manual sprayer; inoculation of primarily the abaxial surface of leaves continued until run-off. After inoculation, the plants remained for 24 h in a dew chamber at an average temperature 22°C, conditions considered optimal for spore germination (Minchio et al 2011) and infection (Infante et al 2009;Martins 2010). Subsequently, the plants were transferred to a greenhouse under ambient conditions and irrigated as needed.…”

Temperaturas e períodos de molhamento foliar no desenvolvimento da ferrugem alaranjada da cana-de-açúcar (Puccinia kuehnii)

“…As condições ambientais favoráveis para o desenvolvimento da ferrugem alaranjada são umidade relativa alta, temperaturas elevadas no verão (13,16) com alternância de calor e frio no outono (13). Sendo as condições ótimas de germinação, de acordo com Magarey et al (14): temperaturas entre 22 e 24 °C e umidade relativa entre 98 e 99%.…”

“…Twenty-day-old plants of the cultivar SP 89-1115 were inoculated with the fungus Puccinia kuehnii at a concentration of 2 x 10 4 urediniospores.mL. Experimental design was completely randomized (DIC), in 5x7 factorial arrangement, representing five temperatures (17.5, 20.0, 22.5, 25.0 and 27.5°C) and seven leaf wetness periods (0, 4, 8,12,16, 20 v.43, n.2, p.132-135, 2017. three replicates. Ideal temperatures for orange rust development were 20.0, 22.5 and 25.0°C, of which the latter was the best.…”