Benedito de Camargo Barros

Efeito da solarização sobre propriedades físicas, químicas e biológicas de solos

Solarization is a method for soil disinfestation, taking effect by increased soil temperatures under soil covers of transparent polyethylene sheets during the period of intense solar irradiation. Four field experiments were set up in the state of Sao Paulo, Brazil (districts of Mogi das Cruzes, Jarinu, Piracicaba and Itatiba), in the years 2000 and 2001, to evaluate the effects of soil solarization on physical, chemical and biological soil properties. Solarization caused a significant reduction in penetration resistance of the evaluated soils in Jarinu, Piracicaba, and Itatiba. In Jarinu, measurements carried out eight months after the removal of the plastic sheet showed that the effect of solarization on penetration resistance was still similar to that observed in the first evaluation. However, in Mogi das Cruzes, in an organic soil, solarization increased the soils penetration resistance in the 2.5-5.0 cm layer. Solarization did not affect the macro-, micro- and total porosity of soils in Piracicaba and Jarinu, where these properties were measured, however it did reduce the apparent density. In an evaluation by fluorescein diacetate hydrolysis, the microbial activity in the soil proved to decrease by solarization. In Mogi das Cruzes, the suppressiveness to Fusarium oxysporum f. sp. phaseoli was evaluated in vitro by colonizing soil samples with an isolate marked with benomyl resistance. Solarization reduced the recovery of the pathogen, indicating an increase in suppressiveness. In solarized plots, there was a significant increase in the concentration of NH4+-N in all experiments, of Mn in three, of NO3--N, Mg2+, and base saturation in two, and K+ in one experiment. On the other hand, the concentration of Cu, Fe, and H + Al decreased in two places, and Zn in one. Results showed that solarization caused changes in physical, chemical and biological soil properties, improving the soil structure, releasing nutrients, and increasing disease suppressiveness.

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.

Iguaçu (IAC-21) e Araguaia (IAC -22): cultivares de trigo de sequeiro para o Estado de São Paulo

Two new selected germoplasms of wheat (Iguacu and Araguaia) were tested against two commercial varieties (BH-1146 and IAC-5) for yield and resistance to stem and leaf rusts in several experiments carried out in different locations of the wheat areas of the State of Sao Paulo, Brazil, in the period 1978-1982. Cultivar Iguacu produced 8% and 12% more grain per hectare in comparison with respectively, cultivars BH-1146 and IAC-5; cultivar Araguaia had, respectively, 5% and 14% more grain yield than the same commercial varieties. Iguacu and Araguaia cultivars presented less stem rust infection than BH-1146 and IAC-5 while Araguaia had a lower infection level than Iguacu under field conditions. It was not observed differences in resistance to leaf rust among them. Araguaia exhibited better bread qualities than Iguacu but both showed better qualities than the used commercial wheat flour.

Comportamento agronômico de linhagens de trigo no Estado de São Paulo

Eighteen wheat lines and the check cultivars IAC-24 and IAC-289 were evaluated in six trials carried out at different locations under dryland and sprinkler irrigation conditions, for grain yield, agronomic characteristics and disease resistance. In laboratory conditions, the germplasms were evaluated for their Al toxicity tolerance in nutrient solutions. The line L9 and the cultivar IAC-289 were superior in grain yield, considering the average of the six trials. The line L8 exhibited short stature associated to lodging resistance and early maturity. In relation to leaf rust the lines L1, L17 and L20 were resistant. All genotypes were susceptible to the causal agents of leaf spot and mildew. The line L7, showed long heads with the highest number of spikelets; IAC-289 and L17, the largest number of grain per head and per spikelet, respectively; and L11, the heaviest grains. All evaluated genotypes were tolerant to Al3+ toxicity, excepting the control cultivar Anahuac and the lines L15 and L20, which exhibited high sensibility.

Melhoramento do trigo: XXV. Avaliação de genótipos oriundos de populações híbridas introduzidas de Oregon (EUA) no Estado de São Paulo

Twenty two inbred lines and three cultivars (BH-1146, IAC-18 and Alondra-S-46) were evaluated in trials carried out with sprinkler irrigation, at Tatui (1985-87) and Mococa (1984) Experimental Station, Campinas (1985) Experimental Center and in a private farm located in Florinea. The following parameters were assessed: grain yield, agronomic characteristics and disease resistance. Tests for resistance to stem and leaf rusts and to aluminum tolerance, were made in greenhouse and laboratory, respectively. In soil with high fertility conditions as in Tatui the line 1 (Novi Sad 738/Bluejay) which is sensitive to Al3+ toxicity, early maturity and semidwarf type, showed good grain yield. Under acid soil conditions, at Mococa, the cultivars BH-1146 and IAC-18, presenting tolerance to Al3+ toxicity, early maturity and tall type, were the most productive. The lines 1,3 (Yaktana-54/Norin10-Brevor//Narino 59/3/Hyslop/4/CIANO/Gallo)and 19(Capitole/Bluetit) and the cultivars BH-1146 and IAC-18 showed the best grain yield considering the mean of the six trials. The lines 2 (Leonardo 23/Bluejay) and 10 (Backa/Alondra) were resistant to two race mixtures of stem rust and to three race mixtures of leaf rust, at seedling stage. These resistances were confirmed in adult stage, under natural (field) infection conditions. The line 2 presented as moderately resistant to powdery mildew, under field conditions. The lines 11 (Backa/Alondra), 15 and 21 (Capitole/Bluetit), 16 (Sava/4/Tezanos Pintos Precoz// //IRN 46/CIANO/3/Protor) and 17 (Vogel Selection 29/Vogel Selection 59--8881//INIA/Caprock/3/Cuckoo) were the most tolerant to Al3+ toxicity, but in a lower degree than that exibited by the cultivars BH-1146 and IAC-18.

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.

Avaliação de linhagens de trigo provenientes de cruzamentos interespecíficos em dois locais no Estado de São Paulo e em laboratório

Eighteen semidwarf type wheat inbred lines, originated from interespecific cross between bread and durum wheat and two control cultivars (IAC-24 and IAC-370), were evaluated in four trials, with four replications, carried out at Capao Bonito, in acid soil without lime application and upland condition, and at Mococa, acid soil with lime application and sprinkler irrigation condition, in 2003 and 2004, in relation to grain yield, plant height and resistance to leaf rust. The tolerance to Al3+ toxicity was evaluated in nutrient solutions containing 0, 2, 4, 6, 8 and 10 mg L-1, in the laboratory. The inbred line 14, in Capao Bonito, was immune to the Puccinia recondita f. sp. tritici, causal agent of leaf rust and was superior for grain yield and tolerance to aluminum toxicity. In the four trials, the cultivars IAC-24 and IAC-370 and the inbred lines 5, 9, 10, 12, 13, 18, 19 and 20 showed moderate resistance to the causal agent of this rust. The inbred line 14 due to the resistance to the causal agent of leaf rust in all trials could be used considered a source of genetic for this character. In general, genotypes were tolerant to aluminum toxicity because they showed root growth after treatment in solution containing 10 mg L-1, except for the cultivar Anahuac sensitive to 2 mg L-1 of Al3+, and the cultivar IAC-370 and the line 13, sensitive to 4 mg L-1 of Al3+. Grain yield in acid soil without lime application in upland condition and plant height were affected in the same way by aluminum toxicity.

Solarização do solo com filmes plásticos com e sem aditivo estabilizador de luz ultravioleta

Visando auxiliar na escolha de filmes plasticos adequados para a solarizacao, dois experimentos foram instalados em Mogi das Cruzes e Piracicaba (SP), em janeiro e fevereiro de 2000. Tres tipos de filmes plasticos transparentes de polietileno de baixa densidade (PEBD), com 100 mm de espessura, produzidos pela empresa Nortene Plasticos Ltda., foram testados: a) FES, filme estufa super tricarpa super aditivado, com aditivo estabilizador de luz ultravioleta (baseado em aminas estericamente impedidas); b) FSOL, filme para solarizacao produzido com metade da quantidade do mesmo aditivo e c) LT, lona plastica transparente, sem aditivo, alem de uma testemunha sem cobertura plastica, em delineamento de blocos casualizados, com quatro repeticoes. Apos a retirada dos plasticos foi conduzida uma safra de alface em ambos os locais. Foi realizada analise quimica dos solos e das plantas colhidas, alem de avaliada a infestacao por plantas daninhas e a massa fresca das plantas colhidas. Em Piracicaba tambem foram realizadas analises microbiologicas dos solos e determinada a viabilidade de Pythium aphanidermattum. Em Mogi das Cruzes foi avaliada a incidencia de podridao de esclerotinia, causada por Sclerotinia minor. As temperaturas medias registradas, a 10 cm de profundidade, nos solos sob os diferentes filmes plasticos foram semelhantes, de 44-41oC nos solos solarizados e de 33,9-30,2oC nos solos nao solarizados de Piracicaba e Mogi das Cruzes, respectivamente. Detectou-se aumento na massa fresca das plantas colhidas nas parcelas solarizadas, de 49% em Piracicaba e 24% em Mogi das Cruzes, independente do plastico testado. Nos dois locais tambem houve drastica reducao na infestacao por plantas daninhas nas areas solarizadas. Nas analises microbianas nao foram verificadas alteracoes na liberacao de CO2, no carbono da biomassa microbiana, no quociente metabolico e no numero total de bacterias. O numero de fungos foi menor nos tratamentos com plastico contendo aditivo. A viabilidade de P. aphanidermatum foi reduzida em todos os tratamentos solarizados, independente do plastico utilizado. Houve aumento no pH, na saturacao por bases (V%) e nos teores de NH4+ (190%), Mn (94,6%) e Mg2+ (18%), dos solos solarizados. Tambem as plantas de alface colhidas nessas parcelas apresentaram maiores teores de Zn (43%), Mg2+ (12%) e K+ (4%). Em Mogi das Cruzes foram observados aumentos nos teores de Mn (236%) e Cu (18%) nos solos solarizados e nas plantas colhidas nesses tratamentos (aumento de 99% para Mn e de 27% para Cu). A incidencia da podridao de esclerotinia foi reduzida de 27,7% na testemunha para indices inferiores a 1% nas parcelas solarizadas com os diferentes filmes plasticos. O plastico sem aditivo estabilizador de luz ultravioleta partiu-se durante ambos os experimentos, apos 60 e 90 dias de exposicao ao ambiente, sendo considerado inadequado para a solarizacao, mas nao houve diferenca entre os plasticos para nenhum atributo avaliado.

Melhoramento do trigo: XIX. Avaliação de novas linhagens em diferentes regiões paulistas

Twenty three inbred lines obtained at the Instituto Agronomico from the wheat breeding program plus the cultivars BH-1146 and Alondra-S-46 were evaluated in field experiments carried out at Campinas Experiment Center, Capao Bonito and Tiete Experiment Stations, and at two farms located in the Paranapanema Valley, during the period 1984-86. Grain yield, plant height, number of days from emergence to flowering and from emergence to maturation, percentage of lodged plants, head length, number of grain per spike and per spikelet, number of spikelets per spike, weight of 100 grains, and resistance to stem and leaf rusts were evaluated under field conditions. The resistance to stem and leaf rusts was tested in the greenhouse, and tolerance to aluminum toxicity was tested in the laboratory. Considering the experiments carried out at Capao Bonito the line 19 presented good productivity showing moderate resistance to Helminthosporium sp. and high tolerance to aluminum toxicity. This line was early in maturity and exhibited tall type of plant but it was resistant to lodging. The cultivars BH-1146 and the line 16 showed high grain yield at the Paranapanema Valley. The line 16 presented a semidwarf type, early maturity, field resistance to leaf rust, resistance to lodging and tolerance to Al toxicity. At Tiete the line 16 showed high productivity. There were no differences among the lines at Campinas. The lines 1, 3, 9, 10, 11, 15, 16, 22, 23 and the cultivars Alondra-S-46 exhibited semidwarf type when compared to the tall cultivars BH-1146. The lines 9, 10, 11 and the cultivars Alondra-S-46 were resistant to stem rust, presenting at seedling stage, resistance to six races under greenhouse conditions. The lines 11, 16, 18 and the cultivars BH-1146 presented low levels of the leaf rust from natural infection out in the field. The line 7 with long heads, the lines 7 and 8 with large number of spikelets per spike, the line 2 presenting high head fertility and the line 21 exhibiting heavy grains were considered as good genetic sources of these characteristics for the wheat breeding program. The lines 1, 3, 5, 12, 13, 14, 16, 17, 18, 19, 21 and the cultivars BH-1146 were tolerant to the presence of 10 mg/liter of Al in the nutrient solution.