Fungos e nematoides associados a sementes de forrageiras tropicais

Abstract

RESUMOPalavras-chave adicionais: Brachiaria brizantha, Panicum maximum, patógeno.Objetivou-se avaliar a incidência de fungos e nematoides em sementes de Brachiaria sp. e Panicum maximum produzidas nos estados de Mato Grosso do Sul (MS), Mato Grosso (MT), Goiás (GO), Minas Gerais (MG) e São Paulo (SP Com a expansão das pastagens e intensificação da atividade pecuária nos últimos anos, várias doenças de forrageiras começaram a ter importância significativa, especialmente nas regiões centro-oeste e norte do Brasil, causando perdas em produtividade e qualidade de pastagens.Pouco se conhece sobre a qualidade sanitária de sementes forrageiras produzidas e comercializadas no país, o que provavelmente contribui para o aumento da incidência de doenças em áreas de pastagens (6).A associação de patógenos às sementes representa impacto significativo no estande, desenvolvimento das plantas, produção de sementes, persistência das forrageiras no campo e, consequentemente, na produção de leite e carne. Além disso, a presença de patógenos nas sementes constitui entrave para a exportação de sementes (2, 3).Amostras de lotes comerciais de sementes de cultivares Brachiaria sp. e Panicum maximum da safra 2009/2010 e produzidas em diferentes regiões produtoras do país foram analisadas quanto à This study aimed to assess the incidence of fungi and nematodes in Bra c h ia ria sp. a nd Pa n ic u m ma x imu m seeds produ ced in the Brazilia n sta tes of Ma to Grosso do Sul (MS), Ma to Grosso (MT ), Goiás (GO), Minas Gerais (MG) and São Paulo (SP). The main fungi found in the seeds were Bipolaris sp., Curvularia sp. and Phoma sp.. The lowest incidence of these fungi was found for seeds of Brachiaria brizantha cultivars BRS Piatã and Xaraés, and Brachiaria decumbens cv. Basilisk, from the states of GO, MG and MS, respectively ABSTRACTB. humidicola cultivar Humidicola, produced in MS and SP, did not show a ssociation with nematodes. T he seeds of Pa nic um ma ximum cv. Massai a nd cv. Mombaça showed higher incidence of Bipolaris sp., Cladosporium sp., Curvularia sp., Fusarium sp. and Phoma sp., as well as Ap he le nc ho id es sp. a nd Dity le nc hu s sp., especially for seeds produced in MT. Some of the detected pathogens are causative a gents of disea ses of ma jor importa nce in fora ge pla nts, such a s Bip o la ris sp., ca u sing lea f spot in Pa n ic u m, of high severity in Ta nzâ nia , which provides seriou s compromising of the pa stu re sustainability.

Physiological and sanitary quality, and transmission of fungi associated with Brachiaria brizantha (Hochst. ex. A. Rich.) Stapf seeds submitted to thermal and chemical treatments

“…When comparing the two harvests, higher total fungal incidence in seeds of the 2011 season was observed, including the untreated seeds (profile), which may have provided an increase in the percentage of dead seeds in this harvest, as seen in Table 3. Among the fungi identified in this study, six were identified by Mallmann et al (2013) in B. brizantha cv. BRS Piatã: Alternaria sp., Bipolaris sp., Cladosporium sp., Curvularia sp., Fusarium sp.…”

Can industrial cleaning procedures make Urochloa ruziziensis seeds nematode free?

“…An effort to prevent the use of low quality pasture seed per se is necessary as the seed are being used not only for cattle farmers, but in integrated crop-livestock system, compromising the livestock sustainability and extending it to crops low yielding (Mallmann et al, 2013). Besides the seed industrial cleaning procedures, associations with other methods must be implemented to guarantee that pasture seeds are nematode free.…”

“…For pasture seeds, the harvest might be directly from plants, avoiding the soil sweeping process (Mallmann et al, 2013;Alves et al, 2017). Favoreto et al (2010) pointed out that control of nematodes in pasture seeds can prevent dissemination, especially considering integrated crop-livestock system and the loss of pasture yield to livestock.…”

Sanitary quality of Brachiaria brizantha cv. Marandu and Xaraés seeds harvested in different states in Brazil

“…Rich) Stapf., the increment in the incidence of pathogens has become a problem of growing importance (EUCLIDES et al, 2010;APARECIDO, 2008). Among the main factors responsible for the occurrence of pathogens in seeds are those of the absence of sanitary standards and the scarceness of information concerning the sanity of seeds produced and commercialized in Brazil (MALLMANN et al, 2013).…”

“…'Marandu' and 'Xaraés' cultivars seeds produced in the states of Mato Grosso, Goiás, and Mato Grosso do Sul (GUIMARÃES et al, 2006;MALLMANN et al, 2013). This type of investigation allows to identify the geographical distribution of the pathogen helping in the process of choosing pathogen-free areas for the production of seeds (AZEVEDO;FARIA, 1982).…”