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básico apresentam maior percentual de pobreza e, consequentemente, graves deficiências nutricionais, que poderiam ser minimizadas pela utilização de subprodutos do arroz, como o farelo. No Brasil, o número de pessoas subnutridas, de 2001 a 2003, ultrapassou 14 milhões, aproximadamente 8% da população (FAOSTAT 2006).

Severe outbreaks of bipartite begomoviruses (family Geminiviridae) have been observed on tomatoes after the introduction of the whitefly Bemisia tabaci (biotype B) in Brazil. The Lycopersicon esculentum line 'TX 468-RG' was identified as one of the best sources of broad-spectrum resistance to species comprising the tomato-infecting Begomovirus complex in Brazil. The genetic basis of resistance to one Begomovirus isolate was investigated using populations from the cross between 'TX 468-RG' (P 1 ) and the susceptible line 'Ohio 8245' (P 2 ). Parental lines, F 1 , backcross (BC) to P 1 and BC to P 2 and F 2 generations were inoculated at the two true-leaf stage using 20 viruliferous whiteflies per plant. Assessment was done two weeks after inoculation based upon visual analysis of symptom expression. The ratio of resistant to susceptible plants closely fit to a single recessive gene (locus) model. The sequence analysis indicated that the Begomovirus isolate used in this assay was closely related to the bipartite Tomato chlorotic mottle virus. Therefore, this gene/locus, was tentatively named tcm-1 (tomato chlorotic mottle virus resistance-1). This locus has been transferred to distinct tomato cultivars and levels of resistance similar to that of 'TX 468-RG' were observed in advanced (F 8 and F 9 ) generations. In addition, breeding lines carrying the tcm-1 locus were also resistant to other Brazilian bipartite tomato-infecting Begomovirus species.

Epicoccum sp. showed in vitro antagonism to the rice pathogens Magnaporthe oryzae, Rhizoctonia solani, Sarocladium oryzae, Monographella albescens and Cochliobolus miyabeanus in dual culture. The colony growth of the rice blast fungus, M. oryzae, was reduced by 42.50%. The lethal doses (LD 50 ) determined based on probit-log dosage response curves at 3 and 6 hours after germination were 393.0 and 326.6 ppm, respectively. The crude extract (600 ppm) reduced appressorial formation by 95.68%. A greenhouse experiment comparing the relative efficiency of conidial suspension and crude extract of Epicoccum sp. in the suppression of leaf blast showed no statistical difference between both application methods. However, the crude extract of Epicoccum sp. (4000 ppm) 48 hours before the application of M. oryzae induced resistance and suppressed leaf blast by 97.6%. Scanning electron microscopy of rice leaves inoculated with crude extract of Epicoccum sp. and challenged with M. oryzae showed appressorial deformation on penetration phase. Peroxidase and β-1,3-glucanase activities increased in plants sprayed with crude extract of Epicoccum sp., 24 hours after the application of the challenger. PAL as well as chitinase activities increased 72 hours after challenge inoculation. Epicoccum sp. was shown to be a potential antagonist and inducer of resistance against M. oryzae.

A mancha de grãos (MG) ocupa o segundo lugar em importância econômica entre as doença s do a rroz. Foi estuda da a influ ência de níveis de adubação nitrogenada, época de plantio e concentração de esporos no ar sobre a severidade da doença no campo. A severidade de MG, na cultivar BRS Bonança, foi avaliada em duas épocas de plantio (30 /11/2006 e 2 1/12 /200 6) e cinco doses de a duba ção nitrogenada (0 , 3 0 , 6 0 , 1 2 0 e 2 4 0 k g de N.ha -1 ) u tiliza ndo o delinea mento experimental de blocos ao acaso em esquema de parcelas subdivididas com três repetições. O efeito de dose de N sobre a severidade de MG nã o foi significa tivo. A correla çã o entre a severida de de MG e espiguetas vazias foi positiva e significativa. A população de fungos no ar (aerosporos) foi quantificada utilizando armadilhas volumétricas, Silva-Lobo, V.L.; Lacerda, M.G.; Filippi, M.C.; Silva, G.B; Prabhu, A.S. Influência da adubação nitrogenada, época de plantio e aerosporos sobre a severidade da mancha de grãos em arroz de terras altas.Summa Phytopathologica, v.37, n.3, p.110-115, 2011. Palavras-chave adicionais:Oryza sativa, armadilha volumétrica, doenças de final de ciclo, epidemiologia.Rotorod Sampler, desde a emissão até o amadurecimento das panículas. A mancha de grãos aumentou linearmente com tempo (r = 0,98; P < 0 ,0 1 ), o mesmo nã o ocorreu com o a u mento tota l de fu ngos qu e variou de 0,23 a 2,97 esporos/litro de ar/minuto. Os fungos presentes no ar em ordem decrescente de concentração foram Nigrospora sp., Pyricularia oryzae, Pithomyces sp., Alternaria sp., Cercospora sp., Fusarium sp., Curvularia sp. e Bipolaris sp. Estes fungos e Phoma sp. entre outros ta mbém fora m detectados no teste de sa nida de de sementes. A correlação entre a quantidade de esporos de P. oryzae e outros fungos foi linear e positiva (r = 0,80, P < 0,01). O número de esporos au mentou com o a umento da u mida de relativa e diminu iu com o aumento da temperatura máxima de maneira exponencial.As principais doenças de final de ciclo em arroz de terras altas incluem a brusone nas panículas [Pyricularia oryzae (Cavara) ] e a mancha de grãos associada a mais de um patógeno fúngico. (4,11,18,20). Keywords:Oryza sativa, volumetric spore trap, diseases of final growth stages, epidemiology. ABSTRACTGra in discolora tion (GD) is ra nk ed second a mong the most economically important rice diseases. The influence of nitrogen levels, planting date and air spora concentration on the disease severity was studied in the field. GD severity in the rice cultivar BRS Bonança was assessed on two planting dates (3 0/11/2006 and 21/12/2006), using five nitrogen levels (0 , 3 0 , 6 0 , 1 2 0 a nd 2 4 0 k g of N.ha -1 ) and a randomized split plot block design with three replicates. The effect of N level on GD severity was not significant. The correlation between GD severity a nd empty spikelets was positive a nd significa nt. T he fungu s popu la tion in the air (a ir spora ) wa s qu a ntified u sing the volu metric tra p Rotorod Sa mpler from pa nicle emergence to Silva...