RESUMO O objetivo deste trabalho foi verificar o potencial de extratos oriundos de plantas medicinais (Rosmarinus officinalis L., Equisetum arvense L. e Moringa oleifera Lam.) e produtos comerciais (a base de extratos vegetais, óleos vegetais e fosfito de potássio) no controle in vitro de Diplocarpon rosae. Avaliou-se o efeito dos tratamentos sobre o fitopatógeno pelo índice de velocidade de crescimento micelial, inibição do crescimento micelial, inibição da esporulação, índice de esporulação, síntese de proteínas, a atividade específica de peroxidase e catalase no micélio do fitopatógeno, utilizando extrato bruto aquoso (EBA) de folhas de R. officinalis (1%); EBA de caules de E. arvense (1%); EBA de sementes de M. oleifera (1%); produto comercial a base de extratos vegetais fermentados (0,01%); produto comercial a base de fosfito de potássio (0,01%); produto comercial a base de óleos vegetais (0,01%); produto a base de massa cítrica (0,01%); fungicida a base de Tiofanato metílico (0,007%); adjuvante (0,0025%) BDA e BD. Pelos resultados observou-se maior redução do crescimento de D. rosae quando na presença do produto comercial a base de óleos vegetais. O EBA de E. arvense e o produto comercial a base de extratos vegetais fermentados apresentaram efeito anti-esporulante. Os tratamentos com EBA de R. officinalis, EBA de E. arvense, EBA de M. oleifera, produto comercial a base de óleos vegetais e produto a base de massa cítrica aumentaram a síntese de proteínas no micélio D.rosae. Houve aumento da atividade específica das enzimas peroxidase e catalase no micélio quando na presença do EBA de R. officinalis e produto comercial a base de fosfito de potássio, respectivamente. O EBA de E. arvense, e os produtos comerciais a base de óleos vegetais e a base de extratos vegetais fermentados, apresentaram resultados promissores no controle do fitopatógeno D. rosae.

ABSTRACT The aim of this study was to verify the potential of extracts derived from medicinal plants (Rosmarinus officinalis L., Equisetum arvense L. and Moringa oleifera Lam.) and commercial products (based on plant extracts, plant oil and potassium phosphite) on the in vitro control of Diplocarpon rosae. The effect of treatments on the phytopathogen was evaluated according to the mycelial growth speed rate, mycelial growth inhibition, sporulation inhibition, sporulation rate, protein synthesis, and peroxidase and catalase specific activity on the mycelium of the phytopathogen, using aqueous crude extract (ACE) of R. officinalis leaves (1%); ACE of E. arvense stems (1%); ACE of M. oleifera seeds (1%); commercial product based on fermented plant extracts (0.01%); commercial product based on potassium phosphite (0.01%); commercial product based on plant oil (0.01%); product based on citrus mass (0.01%); fungicide based on thiophanate methyl (0.007%); and adjuvant (0.0025%) in PDA and PD media. Results showed a higher reduction in the growth of D. rosae in the presence of commercial product based on plant oils. The ACE of E. arvense and the commercial product based on fermented plant extracts exhibited anti-sporulant effect. Treatments with ACE of R. officinalis, ACE of E. arvense, ACE of M. oleifera, commercial product based on plant oil and product based on citrus mass increased protein synthesis in D. rosae mycelium. There was increased specific activity of the enzymes peroxidase and catalase in the mycelium in the presence of ACE of R. officinalis and commercial product based on potassium phosphite, respectively. The ACE of E. arvense and the commercial products based on plant oils and fermented plant extracts showed promising results in the control of the phytopathogen D. rosae.

Considering the importance of blast, caused by Pyricularia oryzae, to reduce wheat yield, this study investigate how silicon (Si) could reduce the wheat blast symptoms in the rachis tissues using light microscopy and scanning electron microscopy. Wheat plants (cv. BR 18) were grown in hydroponic culture with either 0 (–Si) or 2 mM (+Si) of Si. Blast symptoms were very well developed on the spikes of the –Si plants, which showed intense discoloration in contrast with the spikes of the +Si plants. At 72 hours after inoculation (hai), fungal hyphae extensively colonized the epidermis and the collenchyma tissue in the radial direction in the rachis of the –Si plants. In the +Si plants, fungal hyphae colonized the epidermis and the collenchyma cells to a lesser extent than in the –Si plants. At 96 hai, fungal hyphae were observed in the epidermis, vascular bundles and cortical tissue in the rachis node of the -Si plants. In the +Si plants, a phenolic-like material was detected in the parenchyma with lower fungal colonization in comparison with the –Si plants. In scanning electron microscopy, fungal hyphae were scarcely observed in the upper epidermal, collenchyma and parenchyma cells in the rachis tissue of the +Si plants, whereas in the rachis tissue of the –Si plants, fungal hyphae extensively colonized the epidermis, collenchyma, parenchyma and vascular bundles.

O objetivo deste trabalho foi avaliar o efeito do silício (Si) no processo infeccioso de Phakopsora pachyrhizi em folíolos de soja cultivada em solução nutritiva com ou sem Si. Observações realizadas sob microscópio de luz e microscópio eletrônico de varredura indicaram que, nos folíolos das plantas supridas com Si, as urédias foram menores e em menor número. Houve redução de 27, 23 e 60% no número de lesões, urédias fechadas e urédias abertas, respectivamente, nos folíolos das plantas com Si. Plantas de soja supridas com Si apresentam redução nos sintomas da ferrugem-asiática-da-soja.

The objective of this work was to evaluate the effect of silicon (Si) on the infection process of Phakopsora pachyrhizi in leaflets of soybean plants grown in nutrient solution with or without Si. Observations done with light microscope and scanning electron microscope indicated that, in leaflets of plants supplied with Si, uredia were smaller and fewer in number. There were reductions of 27, 23 and 60% in the number of lesions, closed uredia and open uredia, respectively, in leaflets of plants with Si. Soybean plants supplied with Si show reduction in Asian soybean rust symptoms.