Microrganismos associados a frutos de diferentes cultivares de noz Pecan

Abstract

RESUMOO conhecimento do comportamento natural da nogueira Pecan às principais doenças é de suma importância para o estabelecimento do planejamento da implantação da cultura. O controle fitossanitário e tratos culturais devem ser realizados de modo a não comprometerem a qualidade do produto final, as amêndoas. Foram avaliadas nozes produzidas na safra de 2005 e oriundas de Uraí-PR, pelas cultivares Burkett, Frotscher e Moneymaker, para identificar e quantificar os microrganismos associados à amêndoas e cascas dos frutos, bem como observar diferenças entre organismos colonizadores das cultivares. Os frutos foram avaliados na pós-colheita, aos trinta dias de armazenamento em ambiente, através da metodologia do papel de filtro, sendo submetidos ou não à assepsia superficial. O fungo Cladosporium caryigenum, promotor da rancificação das amêndoas foi observado, em amêndoas e cascas, nas cultivares Burkett, Frotscher e Moneymaker; Fusarium sp., foi encontrado em porcentuais elevados, tanto em amêndoas quanto em cascas das três cultivares estudadas; Cephalothecium roseum, causador do mofo róseo em amêndoas, na cultivar Frotscher. Aspergillus sp. e Penicillium sp., causadores de emboloramento e produtores de aflotoxinas foram observados em porcentuais representativos, em amêndoas da cultivar Frotscher e em amêndoas e cascas das cultivares Frotscher, Burkett e Moneymaker, respectivamente. Os maiores porcentuais de perda do rendimento foram observados na cultivar Burkett, por causa da incidência de Colletotrichum sp., causador da antracnose em amêndoas, que acarreta escurecimento e deterioração do produto final, levando-o ao descarte. Termos para indexação:Carya illinoensis, patologia de sementes, sanidade, armazenamento, Cladosporium caryigenum. ABSTRACTThe knowledgement of the natural behavior of the main diseases of Pecan nut is of utmost importance for the stablishment of an implantation plan for that culture. The phytosanitary control and cultural treatments should be performed in order not to change the quality of the final product. Nuts harvest in 2005 from Uraí-PR of Burkett, Frotscher and Moneymaker cultivars, were evaluated in order to identify and quantify associated microorganisms in the nuts and fruit cover, as well to observe the differences among the microorganisms that colonize the different cultivars. The fruits were evaluated at post-harvest, thirty days kept in natural temperature, through filter paper method, being submitted or not to surface assepsy. The fungi Cladosporium caryigenum, rancification promoter to the almonds was observed on almonds and covers on the cultivars Burkett, Frotscher and Moneymaker; Fusarium sp., was observed in high concentration, on almonds as well as on the cover of all the studied cultivars; Cephalothecium roseum, responsible for the pink mildew, in almonds in the Frotscher cultivar. Aspergillus sp. and Penicillium sp., responsible for mold and aflatoxins formation, were observed in high amount on almonds of the Frotscher cultivar and in almonds and cover of Frotscher, Burk...

Mycological quality of pecan nuts from Brazil: absence of aflatoxigenic fungi and aflatoxins

“…media employed. The most common aflatoxin producers are A. flavus and A. parasiticus, which have already been reported in pecans (LILLARD et al, 1970;HUANG & HANLIN, 1975;KOEHLER et al, 1975, TERABE et al, 2008. Penicillium sp., was the most prevalent in one region and the second most prevalent in the other three regions sampled.…”

“…During the different stages of cultivation and processing, pecan nuts are exposed to contamination by a wide variety of microorganisms, especially fungi, which can multiply in this substrate, changing nut quality, producing unpleasant flavors, and even possibly synthesizing mycotoxins, especially aflatoxins (TERABE et al, 2008;PITT & HOCKING, 2009). Among the major fungal species reported in pecan nuts are Penicillium spp.…”

“…Species of Alternaria have been associated with darkly discolored pecan kernels, usually discarded during processing (SCHROEDER & COLE, 1976). TERABE et al (2008) reported important deteriorating and mycotoxigenic microorganisms in pecan nuts produced in Paraná, such as Alternaria sp., A. ochraceus, A. flavus, A. niger, Cladosporium sp., Colletotrichum sp., Fusarium sp., Penicillium sp., and Rhizopus sp. Some species, except for Aspergilli with the potential of producing mycotoxins, are consistent with the results of this research.…”

“…Therefore, this study was the first to investigate the presence of aflatoxins in Brazilian pecan nuts. The researchers (TERABE et al, 2008) studied three growing pecan cultivars (Frotcher, Burkett, and Moneymaker), reporting variation in the infection by toxigenic Aspergilli (both A. flavus, A. niger, and A. ochraceus) during storage, being the Frotcher cultivar the most susceptible to contamination. Moreover, VÁZQUEZ-BARRIOS et al (2001) showed that A. parasiticus develops faster than A. flavus in pecan nuts and that susceptibility to infection by Aspergilli varies significantly within pecan genotypes, suggesting the possibility of selecting pecan cultivars with a high level of resistance to infection by aflatoxigenic species aiming mycotoxin control.…”

Pecan: from Research to the Brazilian Reality

“…[49] states that Barton, Choctaw, Shawnee and Stuart are important cultivars in Brazil. [50] report that Burkett, Frotscher and Moneymaker are the most common ones in Paraná state. There is consensus regarding the fact that a set of cultivars, which is adequate to the technological level, has neither been defined, mainly regarding adaptation and tolerance to climatic and biological adversities, nor had its productive and qualitative potential studied in the region.…”