The mycoflora of 3 hybrids of freshly harvested corn grains collected from three regions of the state of São Paulo, Brazil (Assis, Capão Bonito and Ribeirão Preto) was investigated. A total of 66 samples were analyzed focusing on the influence of abiotic factors (moisture content, water activity, temperature and rainfall) on both the prevalence of Aspergillus flavus and Fusarium moniliforme, and the ability of these genera isolates to produce aflatoxins and fumonisins, respectively. In the three surveyed regions, the fungal population comprised mainly Fusarium spp., Penicillium spp., Aspergillus spp. and 2 others filamentous fungal genera, which were isolated from corn kernels showing water activity of 0.30 to 0.99 and moisture content of 5.0% to 20.2%. Among the genera Fusarium and Aspergillus, the most frequent species were F. moniliforme and A. flavus, respectively. Concerning the toxigenic potential of F. moniliforme, all isolated strains (40) produced fumonisins at 20 µg/g to 2168 µg/g (FB 1 ) and/or 10 µg/g to 380 µg/g (FB 2 ). From the 10 A. flavus isolates, 6 strains (60.0%) produced aflatoxins at 615 µg/kg to 30.750 µg/kg (AFB 1 ) and/or 11 µg/kg to 22 µg/kg (AFB 2 ).

Ten elite maize (Zea mays L.) lines were crossed in a complete diallel scheme and the single-cross hybrids obtained were assessed at four experimental stations of the Agronomic Institute of Campinas, in São Paulo State, Brazil. The experiments were set up in a randomized complete block design with three replications, including four commercial checks. The experimental plots consisted of two 5-m rows spaced at 0.9 m, with a total of 50 plants. The traits assessed included: days to mid-tassel pollen shed (DPS), plant height (PH), ear height (EH), grain yield, corrected for a 50-plant stand and 14% moisture (GY corr.), and resistance to Phaeosphaeria maydis and Puccinia polysora. General and specific combining ability effects (GCA and SCA) were determined. There was extensive genetic variability among hybrids with the best hybrids (HS 04 x 10 and HS 10 x 11) not differing from the commercial checks. The lines with the greatest potential for hybrid synthesis included: L 10, L 11 and L 13, because they had higher GCA for yield, moderate resistance to P. maydis and reduced EH. The greatest contribution to reduction of the Phaeosphaeria stain was obtained with L 5. The magnitude of the GCA relative to the total variation indicated that additive effects predominated for resistance to P. maydis and P. polysora. Significant SCA (P < 0.01) was also found, indicating dominance effects as well.
Cruzaram-se dez linhagens-elite de milho em esquema dialélico completo e os híbridos simples obtidos foram avaliados em quatro Núcleos Experimentais do Instituto Agronômico de Campinas, SP, Brasil. Os ensaios foram instalados sob delineamento de blocos casualizados com três repetições, incluindo quatro testemunhas comerciais. As parcelas consistiram em duas linhas de 5 m espaçadas por 0,90 m, contendo 50 plantas. Avaliaram-se os caracteres: dias para o florescimento masculino (DPS), altura da planta (PH) e da espiga (EH), produtividade de grãos corrigida para estande ideal de 50 plantas e 14% de umidade (GY corr.) e resistência a Phaeosphaeria maydis (Pm) e a Puccinia polysora (Pp). Estimaram-se os efeitos da capacidade geral e específica de combinação das linhagens. Houve grande variabilidade genética entre os híbridos, sendo que os melhores (HS 04 x 10 e HS 10 x 11) não diferiram das testemunhas comerciais. As linhagens de maior potencial para síntese de híbridos no conjunto em questão foram: L 10, L 11 e L 13, por aliarem alta GCA para produtividade, resistência moderada a P. maydis e redução da altura da espiga. A maior contribuição para redução da mancha de Phaeosphaeria foi proveniente de L 5. A magnitude da GCA em relação à variação total corroborou a natureza preponderantemente aditiva da resistência às doenças estudadas. A presença da SCA significativa (P < 0,01) foi também confirmada, indicando a existência de efeitos de dominância

Past surveys indicated that the occurrence of a¯atoxins, zearalenone and ochratoxin A was not a problem in corn and corn products in the state of Sa Ä o Paulo, Brazil. However, according to recent studies, a change in pattern has been detected. To obtain a better overview, these toxins were searched for in 110 samples of freshly harvested corn, corresponding to 48 commercial cultivars planted at three different locations in the state. A¯atoxin contamination was found in 60 (54.5%) of the samples, in levels ranging from 6 to 1600 mg kg À1 a¯atoxin B 1 . Insect control was exercised, so this was not the main route of corn infection. Endosperm type, germplasm type, number of days to¯owering, and length of time the mature corn remained in the ®eld had no effect on a¯atoxin contamination. Ochratoxin A was found in two samples (206 and 128 mgkg À1) and zearalenone in one sample (4640 mg kg À1

Tem-se observado alta tolerância ao alumínio em milho Cateto. Devido à importância dessa característica nos híbridos comerciais e à divergência das informações disponíveis sobre a herança desse caráter, estudou-se a genética da tolerância ao alumínio nas linhagens lp 48-5-3 (Cateto) e Col (22) (duro da Colômbia), e gerações F1, F2 e retrocruzamentos. Estes genótipos foram avaliados em solução nutritiva com 4,5 ppm de alumínio, em dois experimentos conduzidos em Campinas, em 1985. A característica de raiz mais adequada para o estudo foi o crescimento líquido da radícula (CLR). A distribuição de freqüência da geração F2 foi contínua e unimodal, apresentando apenas classes do F1 e do pai tolerante. Deve-se a alta tolerância ao alumínio da linhagem lp 48-5-3, principalmente, à ação de genes menores, de efeitos genéticos aditivos. A herdabilidade no sentido amplo e restrito foi alta, indicando que a seleção de genótipos tolerantes na geração F2 é eficiente.

Twenty three samples, belonging to 19 corn cultivars with distinct types of germoplasms, endosperm and length of vegetative cycle, were analyzed for fumonisins B 1 and B 2. The cultivars were grown in experimental fields in three locations (Votuporanga, Ribeirão Preto and Capão Bonito) within the State of São Paulo, Brazil, during the 97/98 crop. All samples were contaminated with fumonisins with concentrations ranging from 1.63 µg/g to 25.69 µg/g with an average of 5.61 µg/g for FB 1 and from 0.38 µg/g to 8.60 µg/g with an average of 1.86 µg/g for FB 2. In terms of fumonisins, these high levels put the corn cultivated in São Paulo among the most contaminated in the world reported to date.