Genetic diversity was introduced by wild allele introgression, and by introducing new genome structure variations. These results highlight the special possibilities of segmental allotetraploidy and of using lineage recombination to increase genetic diversity in peanut, likely mirroring what occurs in natural segmental allopolyploids with multiple origins.

Peanut, Arachis hypogaea L., is a protein-rich species consumed worldwide. A key improvement to peanut culture involves the development of cultivars that resist fungal diseases such as rust, leaf spot and scab. Over three years, we evaluated fungal resistance under field conditions of 43 wild accessions and three interspecific hybrids of the genus Arachis, as well as six A. hypogaea genotypes. In the first year, we evaluated resistance to early and late leaf spot, rust and scab. In the second and third years, we evaluated the 18 wild species with the best resistance scores and control cultivar IAC Caiapó for resistance to leaf spot and rust. All wild accessions displayed greater resistance than A. hypogaea but differed in their degree of resistance, even within the same species. We found accessions with as good as or better resistance than A. cardenasii, including: A. stenosperma (V15076 and Sv 3712), A. kuhlmannii (V 6413), A. kempff-mercadoi (V 13250), A. hoehnei (KG 30006), and A. helodes (V 6325). Amphidiploids and hybrids of A. hypogaea behaved similarly to wild species. An additional four accessions deserve further evaluation: A. magna (V 13751 and KG 30097) and A. gregoryi (V 14767 and V 14957). Although they did not display as strong resistance as the accessions cited above, they belong to the B genome type that is crucial to resistance gene introgression and pyramidization in A. hypogaea.

Because of damages caused, general occurrence in crops, and high population levels, the most important peanut pest in Brazil is the thrips Enneothrips flavens Moulton (Thysanoptera: Thripidae). A field experiment was carried out during the 2001/2002 growing season, in Campinas and Pindorama, State of São Paulo, Brazil, to evaluate the influence of E. flavens on yield of six peanut cultivars. Treatments comprised three cultivars of the upright type and three of the runner type, with and without chemical control of the insect. Thrips infestation was evaluated by insect countings on young leaflets. Yield and yield reduction percentage due to the lack of thrips control were estimated. The lack of insect control resulted in yield reductions varying from 19.5 to 62.7%, depending on the level of infestation, cultivars, and location. Runner cultivar IAC Caiapo, presented the lowest yield reductions in both locations (19.5 and 28.7%), even when exposed to thrips infestation for a longer period because of its longer cycle. This fact characterizes 'IAC Caiapo' as resistant to E. flavens. Key words: Arachis hypogaea L., Thysanoptera, Thripidae, insecta, host plant resistance INFESTAÇÃO DE ENNEOTHRIPS FLAVENS MOULTON E PRODUTIVIDADE DE CULTIVARES DE AMENDOIMRESUMO: Em função dos danos causados e ocorrência generalizada na cultura, a praga mais importante do amendoim no Brasil é Enneothrips flavens Moulton (Thysanoptera: Thripidae). Com o objetivo de avaliar a influência do ataque de E. flavens na produtividade de seis cultivares de amendoim, foi implantado um experimento em campo, no ano agrícola 2001/2002, em duas localidades do Estado de São Paulo: Campinas e Pindorama. As cultivares de amendoim avaliadas foram três de porte vegetativo ereto e três rasteiros, com controle e ausência total de controle químico da praga. Para a avaliação da infestação de tripes, foram realizadas amostragens a partir dos 29 dias após o plantio, a cada duas semanas, quando foram coletados 10 folíolos fechados por subparcela. Ao final do ciclo, avaliou-se o peso em casca das parcelas e determinou-se o índice de redução na produção provocado pela ausência de controle do tripes nessas cultivares. A ausência de controle do tripes provocou reduções de produção entre 19,5 a 62,7%, dependendo do nível de infestação, da cultivar utilizada e do local de plantio. Embora exposto a um maior período de infestação devido a seu ciclo mais longo, 'IAC Caiapó' apresentou a menor perda produtiva quando não houve controle da praga (19,5 a 28,7%, dependendo da localidade plantada), demonstrando possuir resistência a esse inseto. Palavras-chave: Arachis hypogaea L., Thysanoptera, Thripidae, insecta, resistência de plantas a insetos

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ResumoCom os objetivos de avaliar a qualidade fisiológica e sanitária de sementes de amendoim armazenadas no estado de São Paulo, identificar os principais insetos e fungos que ocorrem nessas condições e as possíveis injúrias causadas que possam prejudicar a qualidade dessas sementes, amostragens de lotes das cultivares IAC 886 e IAC 503, produzidas nas safras 2010/11 e 2011/12, foram realizadas em quatro épocas: antes do armazenamento, antes do beneficiamento, após o beneficiamento e após o tratamento químico. As sementes foram analisadas quanto ao teor de água, germinação, vigor e sanidade. O beneficiamento não melhorou a qualidade das sementes de amendoim. As principais pragas associadas às sementes foram Cyrtomenus mirabilis (Perty) e Corcyra cephalonica (Stainton). Os fungos mais frequentes foram os dos gêneros Aspergillus, Fusarium, Penicillium e Rhizopus. Durante o armazenamento houve aumento na incidência de Aspergillus spp., Penicillium spp. e Rhizopus sp. e redução da ocorrência de Fusarium sp. O tratamento das sementes de amendoim, após o beneficiamento, é imprescindível para serem obtidos padrões aceitáveis à sua comercialização.Palavras-chave: Arachis hypogaea L., germinação, armazenamento, insetos praga, fungos, beneficiamento. Quality assessment of commercial peanut seeds in the state of São Paulo, Brazil AbstractPhysiological and sanitary quality of peanut seeds stored in the state of São Paulo were assessed in seed lots of cultivars IAC 886 and IAC 503 harvested in the 2010/11 and 2011/12 growing seasons. Evaluations also included the identification and damages caused by fungi and insects occurring in these conditions. Seed sampling and evaluations were done in four stages of the seed storing and processing: before storage, before shelling, after shelling and after seed treatment. Seeds were analyzed for water content, germination and vigor, and evaluated for sanity. Shelling did not improve physiological and sanitary quality of the seeds. Cyrtomenus mirabilis (Perty) and Corcyra cephalonica (Stainton) were the main insects found. The fungi most frequently detected were those of genus Aspergillus, Fusarium, Penicillium and Rhizopus. Increased occurrence of Aspergillus, Penicillium and Rhizopus, and decreased occurrence of Fusarium were noted during the storage period. Seed treatment after shelling was proved to be essential for reaching the necessary quality standard of commercial seeds.