Severidade da antracnose e produtividade de sorgo granífero em resposta a doses crescentes de nitrogênio / Anthracnose severity and yield of grain sorghum in response to increasing nitrogen doses

O presente estudo objetivou avaliar a severidade da antracnose e a produtividade de diferentes genótipos de sorgo em resposta a doses crescentes de nitrogênio. Os experimentos foram conduzidos em duas safras agrícolas: safra 2009/2010 (safra I) e safra 2010/2011 (safra II). O preparo do solo na área experimental foi realizado de forma convencional. Na safra I foram utilizados quatro genótipos de sorgo BRS 310, CMSXS 0144015, CMSXS 9920045 e CMSXS 9920044, enquanto que na safra II apenas os genótipos BRS 310 e CMSXS 0144015 foram avaliados. Aos 45 dias após o plantio (DAP) foram aplicados os tratamentos que consistiram de doses de nitrogênio (67; 112; 157; e 202 kg ha-1) em adubação de cobertura. Aos 60 DAP, iniciou-se a avaliação da severidade da antracnose utilizando escala de notas. Na colheita, determinou-se a produtividade de grãos nos tratamentos. Houve variação nos níveis de severidade da antracnose e na produtividade de grãos dos genótipos de sorgo em função das doses de nitrogênio aplicadas. Os genótipos de sorgo CMSXS 9920045 e BRS 310 apresentaram menor e maior suscetibilidade à antracnose, respectivamente. No genótipo BRS 310, a doença progrediu mais rapidamente na safra I que apresentou maior umidade relativa.

The present study aimed to evaluate the severity of anthracnose and yield of different genotypes of sorghum in response to increasing levels of nitrogen. For this, experiments were conducted in two agricultural seasons: crop season 2009/2010 (crop season I) e crop season 2010/2011 (crop season II). The soil preparation in the experimental area was performed in conventional manner. In the crop season I were used four sorghum genotypes BRS 310, CMSXS 0144015, CMSXS 9920045 e CMSXS 9920044, whereas in the crop season II only the genotypes BRS 310 and CMSXS 0144015 were evaluated. At 45 days after planting (DAP) were applied the treatments which consisted of nitrogen doses (67; 112; 157; and 202 kg ha-1) in topdressing. At 60 DAP, was began the evaluation of anthracnose severity using notes scale. At the harvest it was determined the yield for each treatment based on the mass of grain. There was variation in levels of anthracnose severity and grain yield in the sorghum genotypes in response to nitrogen levels applied. The sorghum genotypes CMSXS 9920045 and BRS 310 showed smaller and higher susceptibility to anthracnose, respectively. In genotype BRS 310, the disease progressed more rapidly in the crop season I that showed major relative humidity.

Bioprospection of yeasts as biocontrol agents against phytopathogenic molds

Yeasts isolated from sugar cane and maize rhizosphere, leaves and stalks were screened against the phytopathogenic molds Colletotrichum sublineolum and Colletotrichum graminicola, both causal agents of the anthracnose disease in sorghum and maize, respectively. Strains identified as Torulaspora globosa and Candida intermedia were able to inhibit the mold growth, with the first species also exhibiting killer activity. No previous report on the application and potentiality of these yeasts as biocontrol agents were found neither the killer phenotype in Torulaspora globosa.