Progresso da brusone nas folhas e panículas de genótipos de arroz de terras altas Progress of leaf and panicle blast in upland rice genotypes

Foram avaliados dezesseis genótipos de arroz quanto ao seu nível de resistência parcial à brusone (Pyricularia grisea). A reação dos genótipos à doença foi avaliada durante dois anos, em condições de cultivo de terras altas, no município de Capão Bonito, SP. A severidade da doença nas folhas e panículas foi determinada periodicamente, e os dados foram utilizados para traçar a curva de progresso da doença e cálculo da área sob a curva de progresso da doença para cada genótipo (ASCPD). Os resultados evidenciaram que, considerando os dois anos de avaliação, menores valores de ASCPD foram apresentados nas folhas pelas linhagens IAC 1711, IAC 1774 e IAC 1781 e pelas cultivares BRS Bonança e BRS Liderança; nas panículas, pelas linhagens IAC 1738, IAC 1774 e IAC 1781 e pelas cultivares BRS Bonança, BRS Liderança e Carisma.<br>Partial resistance of sixteen rice genotypes to blast (Pyricularia grisea) was evaluated during two years under upland conditions (Capão Bonito, SP). Blast severity on leaves and panicles was periodically determined and the data were used to obtain the disease progress curve for each genotype and to estimate the area under disease progress curve (AUDPC). Smaller AUDPC values were presented, considering leaf blast, by IAC 1711, IAC 1774 and IAC 1781 lines and BRS Bonança and BRS Liderança cultivars; considering panicle blast, by IAC 1738, IAC 1774 and IAC 1781 lines and BRS Bonança, BRS Liderança and Carisma cultivars

Multi-location testing to identify oat germplasm with partial resistance to crown rust

Partial resistance to cereal rusts is characterized by reduction in pathogen reproduction despite a susceptible infection type (Parlevliet, 1985). In some pathosystems (e.g. blast in tropical lowland rice) such resistance has proved to be durable (Bonman et al., 1992). To identify oat germplasm with partial resistance to crown rust, caused by Puccinia coronata, a multilocation screening trial was initiated in 2002. Eighty-six entries were tested at 3 locations planted in the fall of 2002 in the southern US and at 5 locations planted in the spring of 2003 in the midwestern US and Canada using at least 2 replications per site. The line MN841804 was the resistant check and cultivars Brooks and Otana were susceptible checks. The resistant check showed an average disease level of 7.5% relative to the susceptible checks across locations. One entry, the cultivar CDC Boyer, may have a useful level of partial resistance for areas less prone to the disease. In the present study it averaged 24.5% disease relative to the checks across locations. CDC Boyer and 26 other lines showing relative severity values between 3% and 25% and low variation between locations were selected for further testing in 2004. Also, adult plants of CDC Boyer, OT389 (12.1% across locations) and IA98822-2 (17.6% across locations), are undergoing greenhouse tests with compatible races of P. coronata. Further field and greenhouse experiments are planned with these and other lines to ascertain if the lower disease level in field trials is correlated with partial resistance assessed in controlled inoculations. Bonman, J.M. et al. 1992. Annual Review Phytopathology 30:507-528; Parlevliet, J.E. 1985. In: Roelfs, A.P. and W.R. Bushnell (eds.) The Cereal Rusts vol. II. New York, Academic Press, Inc. p. 501-525.vokMyynti MTT tietopalvelu