Eduardo Sawazaki

Mycoflora and aflatoxin/fumonisin production by fungal isolates from freshly harvested corn hybrids

A microbiota fungica de 66 amostras de tres hibridos de graos de milho recem-colhido, provenientes de 3 regioes do Estado de Sao Paulo - Brasil (Assis, Capao Bonito e Ribeirao Preto), foram analisadas perante a influencia dos fatores abioticos (teor de umidade, atividade de agua, precipitacao pluvial e temperatura media) na frequencia de isolamento de fungos, bem como a potencialidade toxigenica das cepas de Aspergillus flavus e Fusarium moniliforme quanto a producao de aflatoxinas e fumonisinas, respectivamente. As analises microbiologicas demonstraram predominância de Fusarium spp., Penicillium spp. e Aspergillus spp. e outros dois generos de fungos filamentosos, isolados de graos com atividade de agua entre 0,30 e 0,99 e teor de umidade entre 5,0% e 20,2%. Entre Fusarium spp, F.moniliforme foi a mais frequentemente isolada, enquanto que, em relacao ao genero Aspergillus, predominou A. flavus nas tres regioes. Todas as cepas de Fusarium moniliforme isoladas (40), produziram fumonisinas, que variaram de 20 mg/g a 2168 mg/g (FB1) e 10 mg/g a 380 mg/g (FB2). Referente a 10 cepas de Aspergillus flavus isoladas, 6 cepas (60,0%) produziram aflatoxinas, que variaram de 615 mg/kg a 30.750 mg/kg (AFB1) e 11 mg/kg a 22 mg/kg (AFB2).

Genetics of aluminum tolerance in maize Cateto

Maize Cateto inbred line has shown high aluminum tolerance. Due to the importance of this trait in commercial hybrids as well as the lack of consistent informations about the inheritance mechanism involved, the genetics of aluminum tolerance in one maize Cateto inbred line was studied. The inbred lines lp 48-5-3 (Cateto), Col 2(22) (flint from Colombia) and the F1, F2 and backcrosses generations were used. Two replicated experiments were carried ou at Campinas, State of Sao Paulo, Brazil, in 1985, to evaluate these genotypes grown in nutrient solutions containing 4.5 ppm of Al. Radicle net growth (CLR) was the most adequate measurement to distinguish maize genotypes for Al tolerance. The F2 frequency distribution was continuous, unimodal and yielded only classes resembling those of the F1 and the tolerant parent. The high Al tolerance of the maize inbred line lp 48-5-3 was due to the action of additive minor genes. Both broad and narrow sense heritabilities were high, indicating that plant selection in F2 generation for Al tolerance is efficient.

Oito ciclos de seleção entre e dentro de famílias de meios irmãos no milho IAC-1

This paper presents the results of eight cycles of selection among and within half-sib families in the IAC-1 maize population. It was obtained an average progress of 1.9% per cycle in grain yield against an expected genetic progress of 8.8% per cycle. For ear index it was estimated an expected genetic progress of 1.5% per cycle if applied the same differential selection index as for yield. Nevertheless it was not done any systematic selection among progenies for this character. The percent of lodging did not alter greatly with the cycles of selection.

Desempenho de híbridos top crosses de linhagens S3 de milho em três locais do Estado de São Paulo

The present work aimed to evaluate the performance end high parent heterosis of 27 hybrids of partially endogamic lines (S3) obtained from commercial hybrids, using top cross squemes with testers (IA 33). Also, the general combining ability (GCA) of the lines was evaluated. The 27 top cross hybrids, two commercial checks and the tester were evaluated by complete block design with three replications, in two years (2005/2006 e 2006/2007), and three locations (Campinas, Mococa and Palmital) of Sao Paulo State. The evaluated traits were: plant height (AP), ear height (AE), percentage of broken and loged plant (AC+Q), ear yield (PE) and grain yield corrected of 14% moisture (PG). Top cross hybrids of high yield performance that outperformed or did not differ from the commercial check were observed. Therefore top cross hybrids with high yield performance and with advantage of small production cost were identified. Also line S3 with high value of GCA were observed.

Accumulation of fumonisins B1 and B2 in freshly harvested Brazilian commercial maize at three locations during two nonconsecutive seasons

Fifty-six Brazilian commercial maize cultivars were examined for FB1 and FB2 accumulation after two non-consecutive growing seasons. During the 94/95 growing season 35 cultivars were planted at three locations in the state of São Paulo, Brazil. All samples (total of 105) were contaminated (0.10 μg/g–6.58 μg/g FB1 and 0.04 μg/g–2.15 μg/g FB2). During the 97/98 growing season, 8 of the cultivars used during 94/95 and 21 others were replanted at the same locations. All 87 samples were contaminated (1.15 μg/g–43.80 μg/g FB1 and 0.08 μg/g–11.65 μg/g FB2). One cultivar accumulated significantly less fumonisins in all locations during both growing seasons, indicating that some degree of selection may be possible even in climates that favor F. moniliforme (verticillioides) infection of maize. The presence of water surplus in soil from kernel maturity to harvest correlated with concentrations of FB1 in the grain for the 8 cultivars planted during both seasons at three locations. Observed trends indicated that water excesses and deficits from silking to harvest increased fumonisin levels. The difference in the incidence of FB1, FB2, and FB1 + FB2 was significant between growing seasons, planting locations and between cultivars. Neither the level of hybridization, nor the type of endosperm, nor the length of the vegetative cycle showed any effect on the FB1 contamination.

Avaliação de cultivares de milho verde em pariquera-açu

Os cultivares de milho Cargill 742, Cargill 408, Cargill 511, Cargill 501, Agroceres 162, Pioneer X 307, IAC Phoenyx 1918, IAC Phoenyx o2 1313, IAC Maya XIX e BR 126 foram avaliados em duas epocas, em plantios de inverno (maio e junho de 1983) na Estacao Experimental de Pariquera-Acu, SP, com o objetivo de identificar os melhores para a producao de milho verde. Foram estudadas as seguintes caracteristicas agronomicas: estande final; numero e total de espigas comerciaveis; peso de espigas com palha, comerciaveis e total; indice de espigas (numero de espigas comerciaveis/estande final) e peso medio de espigas comerciaveis. Os cultivares se diferenciaram quanto a populacao final de plantas; indice de espigas; resistencia a Helminthosporium turcicum Pass.; ciclo do plantio a colheita, e produtividade: o Cargill 742 e o Cargill 408 foram os mais produtivos, superando o Agroceres 162, e mostraram ainda menor incidencia de Helminthosporium turcicum, maior indice de espigas e precocidade. As condicoes climaticas foram atipicas, desfavoraveis a cultura do milho, provocando baixo nivel de produtividade, que ainda foi lucrativo.

Desempenho de híbridos triplos de milho obtidos de top crosses em três locais do Estado de São Paulo

ABSTRACT PERFORMANCE OF MAIZE TRIPLE CROSS-WAY HYBRIDS IN THREE ENVIRONMENTSIN SAO PAULO STATE, BRAZIL The objectives of this investigation were to study the combining ability of 30 lines of the maizebreeding program of the Instituto Agronomico, Sao Paulo State, Brazil, in top crosses squemes, aimingat to identify lines for developing high yield triple cross hybrids with two testers (single cross hybrids).The 60 top crosses along with two checks were evaluated in 2001/2002, in two experiments, named TC1and TC2, following a randomized complete block design with three replicates, over three locations: ( 1 ) Recebido para publicacao em 27 de outubro de 2005 e aceito em 14 de agosto de 2006.( 2 ) Centro de Analise e Pesquisa Tecnologica do Agronegocio de Graos e Fibras, Instituto Agronomico (IAC), Av. Baraode Itapura, n.1481, 13020-902 Campinas (SP). E-mail: elisa@iac.sp.gov.br, * Autora correspondente; sawazaki@iac.sp.gov.br,rrluders@iac.sp.gov.br.( 3 ) Bolsista da FAPESP.( 4 ) Polo Regional de Desenvolvimento do Medio Paranapanema (APTA), Caixa Postal 263, 19800-000, Assis (SP). E-mail:aildson@femanet.com.br.(

POTENCIAL DE HÍBRIDOS TEMPERADOS DE MILHO PIPOCA EM CRUZAMENTOS COM O TESTADOR SEMITROPICAL IAC 12

Com o objetivo de verificar se a posicao da semente na espiga afeta diferentemente a produtividade e outros caracteres da planta e se essa diferenca pode ser ampliada por meio de ciclos seletivos, foi conduzido o presente trabalho. Para isto, na safra 1995/1996, foram semeadas, em lote isolado, cerca de 3.000 plantas da populacao CMS-39 e, por ocasiao da colheita, tomadas 300 espigas ao acaso. De cada espiga, foram coletadas sementes das extremidades e, posteriormente, as sementes da ponta de cada espiga foram misturadas e o mesmo foi realizado com as sementes da base. Esse procedimento foi repetido de modo analogo por cinco ciclos seletivos. As dez subpopulacoes, cinco da ponta e cinco da base, foram avaliadas em experimentos conduzidos nas safras 2000/2001 e 2001/2002. O delineamento utilizado foi o de blocos casualizados, com seis repeticoes, segundo esquema de parcelas subdivididas. Os tratamentos nas parcelas foram os cinco ciclos seletivos e, nas subparcelas, a origem das sementes, ponta ou base. Foram considerados os caracteres numero de dias para o florescimento masculino e feminino, altura de espiga e produtividade de graos. Constatou-se que a origem da semente da ponta ou da base nao alterou a expressao de varios caracteres avaliados e nao foi possivel, com a precisao experimental obtida, detectar efeito da selecao indireta para o vigor de polen pela posicao dos graos na espiga, em todos os caracteres considerados.

HERANÇA DA RESISTÊNCIA DE MILHO A MELOIDOGYNE JAVANICA

In order to study the inheritance of resistance to Meloidogyne javanica in corn (Zea mays), two inbred lines, IAC Ip 365-4-1 (resistant) and IAC Ip 48-5-3 (susceptible), F1, F2 and backcrosses, as well as reciprocal crosses were evaluated in two greenhouse trials, carried out at Campinas, State of Sao Paulo, Brazil, in 1989/90 and 1992. Completely randomized design was utilized with more replications on segregating generations. The plot was one plant per plastic pot with 500 cm3 of fine sand treated with methyl bromide and fertilized with NPK. Five days after seed germination, each plot was inoculated with 5,000 eggs and larvae of M. javanica. Egg mass index, number of eggs per gram of fresh roots and reproduction factor were evaluated 70 and 60 days after inoculation, respectively in the first and second experiment. Reciprocal crosses showed no significant differences. F1 average, frequency distribution of F2 population and monofactorial segregation indicated that resistance of IAC Ip 365-4-1 to M. javanica was due to one major dominant gene and a minor polygenic effect.

Influência da adubação mineral NPK sobre a qualidade da semente de milho

Evaluation of possible effects of mineral nutrition on seed quality characteristics was made using seed of a permanent corn fertilization trial. The following determinations were made: 100 seeds weight, initial humidity content, germination percentage and vigor test (accelerated aging and first count). The first determination of germination percentage and first count was made after one month following of harvest and later every six months until 25 months of storage under laboratory conditions. The results showed that there was a main negative effect of phosphorus, either alone or interaction with N or K on the germination percentage. Vigor test (first count) did not show influence of fertilization on seed quality at the differents periods of storage. In most of the tests, grain yield and 100 seeds weight were negatively correlated with seed quality characteristics.Colhendo as sementes de um ensaio permanente de adubacao mineral NPK de milho, procurou-se avaliar possiveis efeitos da aplicacao de fertilizantes sobre algumas caracteristicas de qualidade da semente. Foram feitas as determinacoes seguintes: peso de cem sementes, teor de umidade inicial, porcentagem de germinacao e testes de vigor (envelhecimento rapido e primeira contagem). A porcentagem de germinacao e a primeira contagem foram realizadas desde o primeiro mes apos a colheita e, subsequentemente, de seis em seis meses, num total de 25 meses de armazenamento em condicoes de laboratorio. A principal observacao foi um efeito negativo marcante do fosforo, tanto isolado quanto em interacao com um ou mais elementos, sobre a porcentagem de germinacao. Pelo teste de vigor (primeira contagem), a qualidade das sementes nao foi influenciada pela adubacao nas diversas epocas de armazenamento. Na maioria dos casos estudados, as caracteristicas de producao de graos e peso de cem sementes correlacionaram-se negativamente com caracteristicas de qualidade da semente.