Jairo Lopes de Castro

Resposta de cultivares de trigo (Triticum aestivum L.) ao controle químico das principais doenças fúngicas da cultura

Leaf rust, leaf spot or brown spot and powdery mildew, caused by Puccinia recondita tritici, Bipolaris sorokiniana and Blumeria graminis tritici, respectively, are wheat diseases that may severely decrease crop yield. Several practices are recommended for the control of these diseases such as cultivar resistance, planting at a suitable time, and chemical control, without which the crop frequently becomes uneconomical. The objective of the present work was to evaluate, under field conditions, the response of six wheat cultivars, IAC 24, IAC 289, IAC 350, IAC 362, IAC 364 and IAC 370, in four experiments, carried out from 2000 to 2003 at Capao Bonito, State of Sao Paulo, Brazil. The experiments were set out in a randomized block design with four replications, and analyzed as a 2 x 6 factorial, being fungicide treatment (with and without) the factor 1 and cultivar the factor 2. Severity of the diseases was graded in a scale that ranged from 0 to 9, (0 = without symptoms and 9 > 60% of the foliar area affected by disease). Grain yield and the thousand kernel weight (TKW) were also assessed in each experiment. Powdery mildew was only observed in 2000, but leaf rust was detected in all years in high severity indexes (30 to 60% of leaf area affected by the disease). Leaf spot, detected in the last three years, from 2001 to 2003, showed the highest severity indexes in the rainiest year, 2001 (up to 60 % of the leaf affected by the disease). In all years the fungicides were efficient to control the diseases in all experiments and resulted in higher TKW and in grain yield increases. The cultivars with the longest crop cycles, IAC 370, IAC 289 and IAC 350, had the highest responses in yield to the chemical control, despite the fact that the last two cultivars were less affected by the diseases in the control plots, showing that not only cultivar resistance, but the crop cycle and the yield potential, characteristic of each cultivar, were important in the response to the chemical control.

TEMPERATURA-BASE, GRAUS-DIA E DURAÇÃO DO CICLO PARA CULTIVARES DE TRITICALE (1)

BASE-TEMPERATURE, GROWING DEGREE-DAYS AND CROP GROWTH CYCLE DURATION OF TRITICALE CULTIVARS Base temperature, growing degree-days and cycle growth length were evaluated at Capao Bonito, Sao Paulo State (Brazil), during the years from 1992 to 1995, for three triticale cultivars: CEP 15, IAC 2 and IAC 3. The obtained values of base temperature varied from 8 to 10 o C and the amount of growing degree-days required for the triticale cultivars to complete their cycle varied from 1048 to e 1263, according to the cultivar. The duration of the emergency-flowering growth stage varied from 50 to 63 days, according to the cultivar, while the duration of the flowering-maturation (harvest) growth stage was 70 days for the three cultivars analised. The low air temperature enlarged the length of the total cycle for the triticale cultivars.

Linhagens diaplóides de trigo: desempenho agronômico em dois locais do estado de São Paulo e tolerância à toxicidade de alumínio em laboratório

Twenty wheat genotypes (18 dihaploid lines and the IAC-24 and IAC-370 cultivars) were evaluated in experiments carried out under dryland and acid soil conditions in Capao Bonito and under sprinkler irrigation and limed soil conditions in Tatui in 2001-03 period. Grain yield, yield components, agronomic characteristics and disease resistance were evaluated. The genotypes were also evaluated for their tolerance to Al toxicity, in nutrient solutions, under laboratory conditions. IAC-24 and the dihaploid lines (L3, L4, L5, L8, L14, L15, L16, L17, L18, L19 e L20), in Capao Bonito, were superior for grain yield. In nutrient solutions, these were the most tolerant genotypes to aluminum toxicity. All genotypes exhibited semi-dwarf plant type. The dihaploid line L15 and L16, presented lodging resistance, IAC-370 longer spikes and higher number of grain per spike and per spikelet, L8 higher number of spikelets per spike and L6 and L7 the heavier grains. All evaluated genotypes were susceptible to leaf spot. The lines L4, L14, L15, L16, L17 and L18 originated from the cross R27/GHL121//KAL/BB/3/BUC/BUL/4/IAC-24 showed resistance to leaf rust. The higher grain yield genotypes, under dryland and acid soil conditions, were associated to taller semi-dwarf plants with tolerance to aluminum toxicity. Under sprinkler irrigation and limed soil conditions the highest yielding genotypes were not associated to either semi-dwarf plants or those tolerant to aluminum toxicity.

Comportamento de linhagens diaplóides de trigo em dois locais do Estado de São Paulo

Twenty wheat genotypes (18 dihaploid lines and the IAC-24 and IAC-289 cultivars) were evaluated in experiments carried out under dryland and acid soil conditions in Capao Bonito (1997-99), and under sprinkler irrigation and acid soil conditions with lime application in Tatui (1997-2000). Grain yield, yield components, agronomic characteristics and disease resistance were analyzed. In addition, the genotypes were evaluated for their tolerance to Al toxicity, in nutrient solutions, at laboratory conditions. The dihaploid lines 10 and 11 and the cultivar IAC-24, in Capao Bonito, and the cultivar IAC-24 and the dihaploid line 19, in Tatui, were superior for grain yield. The dihaploid line 5 presented lodging resistance, the line 20 showed short stature and early plants to mature, and the cultivar IAC-289 exhibited higher number of spikelets per spike and heavier grains. All evaluated genotypes were susceptible to leaf spot. In relation to leaf rust, all lines were resistant, except the line 20 which was moderately resistant. The cultivar IAC-24 and all evaluated dihaploid lines were tolerant to aluminum toxicity. The higher grain yield genotypes, under dryland and acid soil conditions, were associated to tall plants, with long spikes, with high number of grains per spike and per spikelet and with tolerance to aluminum. Under sprinkler irrigation and acid soil conditions with lime application the most productive genotypes were associated to tall plants (semidwarf type) with heavy grains, and presenting no correlation with tolerance to aluminum.

Gomose da acácia-negra causada por Ceratocystis fimbriata Ell. & Halst.

Several plants of Acacia decurrens showed wilting and subsequent branche drying. The branches showed wood splitting and gum exudation. The transversally cut wood showed ashy colored pith, that desenvolved numerous perithecia when kept in a humid chamber. These perithecia were transferred aseptically to potato-dextrose-agar and the culture was classified as Ceratocystis fimbriata Ell. & Halst. Four mounth old Acacia plants inoculated with the isolate died after 14 days. The fungus was again isolated from these dead plants. Cross inoculation tests with isolate of C. fimbriata from Acacia and mango (Mangifera indica L.) showed pathogenic effects for both hosts.

Época de florescimento e horas de frio para pessegueiros e nectarineiras

Blossom dates for 41 peaches and nectarines accesses from the Active Gene Bank (BAG) of stone fruits were evaluated at Capao Bonito (SP), Brazil. Observations of flowering date (70% of opened flowers) were taken and compared to the chilling hours requirement (NHF) considering 7.2 and 13oC. The NHF was estimated using multiple regression equations based on maximum and minimum temperature. The accesses from the BAG were separated by cluster analysis into four groups for peaches and three for nectarines by cluster analysis. The following peaches accesses: IAC 2485-6, IAC 680-13 and Regis and for nectarine: IAC N 785- 9 showed flowering date before July 10th with NHF less than 40 and 500, below 7.2 and 13oC, respectively. The peach cultivars Eldorado, Diamante, Arlequim, Bolao, and Marli showed blossom dates after August 1st, requiring more than 70 and 650 NHF bellow 7.2 and 13oC, respectively. The main peach cultivars for Sao Paulo State like: Aurora-1, Douradao and Dourado-1, flowered from July 11 to 20 with NHF from 41 to 50 bellow 7.2oC and from 501 to 560 bellow 13oC.

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.

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.

Melhoramento do trigo: XXIII. Avaliação de linhagens na região do vale do Paranapanema, em Capão Bonito e em Tietê, em 1984-88

Twenty two inbred lines from the wheat breeding program at the Instituto Agronomico of Campinas, plus the cultivars BH-1146, Alondra-S-46 and Anahuac were evaluated in six field experiments carried out at different locations of the Paranapanema Valley, during the period of 1984-88. Grain yield, plant height, number of days from emergence to flowering, percentage of lodged plants, head length, number of grains per spike and per spikelet, number of spikelets per head, weight of 100 grains, and resistance to stem and leaf rusts, to leaf spots due to Helminthosporium sp. and Septoria sp., and to powdery mildew were evaluated under field conditions. Tests for resistance to stem and leaf rusts and to aluminum tolerance, were performed in greenhouse and laboratory, respectively. The genotypes were also evaluated in trials carried out on acid soil at Capao Bonito and under high soil fertility condition at Tiete. At Paranapanema Valley and Capao Bonito the line 19 (CNT-9 x BH-1146) = IAC-227 showed good grain yield presenting medium cycle and medium plant heigth. At Tiete, jhe lines with a medium cycle from emergence to flowering were the most productive: 1 (Alondra-S-46 x IAC-5) = IAC-225 and 17 (Alondra-1 x IAC-5) = IAC-226, of short plants; and the line 3 (Alondra-S-46 x C-3), of tall plants. The line 21 (IAC-5 x Alondra-S-46) was resistant to: (a) two race mixtures of stem rust; (b) leaf rust, under field condition and two race mixtures of this rust, under greenhouse condition; (c) powdery mildew in adult stage of plants; and (d) leaf spots, showing a relatively low amount of them, under field condition. The lines 6 (C-3 x Sonora-64) and 17 (Alondra-1 x IAC-5) showed to be good genetic sources for long head, the line 17 for large number of spikelets and grains per head, the line 10 (Jupateco x IAC-13) for large number of grains per spikelet and the line 5 (Tobari-66 x BH-1146) for heavy grains. The lines 7, 9, 13, 16, 17 and 19 and the cultivar BH-1146 exhibited tolerance to the presence of 10 mg/liter of Al3+ in the nutrient solution.

Trigo: três épocas de semeadura em Capão Bonito, SP, no período 1981-85

Neste trabalho, procurou-se estudar o comportamento de dezoito cultivares de trigo semeados em tres epocas (3o decendio de marco, 2o decendio de abril e 3o decendio de maio) na Estacao Experimental de Capao Bonito, regiao Sul do Estado de Sao Paulo, no quinquenio 1981-85. Efetuaram-se, em cada epoca de semeadura, avaliacoes de rendimento de graos, resistencia as doencas, altura das plantas, peso hectolitrico e de mil graos. Estudou-se a disponibilidade hidrica do solo, atraves de balancos hidricos decendiais, considerando 125mm como a capacidade de retencao de agua no solo. Os resultados indicaram como melhor epoca de semeadura 21 a 31 de marco. A ocorrencia de molestias foi altamente influenciada pelas condicoes climaticas verificadas em cada ano, sobretudo a helmintosporiose. Os cultivares CNT 7, BR 1, Paraguay 281, CNT 8, BH 1146, IAC 18 e IAC 5 apresentaram as maiores producoes de graos nas semeaduras de 21 a 31 de marco, nao diferindo estatisticamente entre si. As correlacoes entre altura media e producao de graos na primeira e na segunda epoca foram significativas, mostrando que, nessas condicoes, os cultivares de porte mais alto foram tambem os mais produtivos. O peso de mil graos foi o componente da producao que melhor expressou as diferencas de comportamento entre os cultivares estudados nas diferentes epocas de semeadura em todo o periodo.