Norberto A. Lavorenti

Evaluation of the effects of sugarcane straw coverage in moisture and water loss of soil.

In the period from June 23 to July 23, 2006, in the regional environment of Araras-SP, it was studied the influence of sugarcane straw coverage harvested mechanically in water content of a dystrophic dark-red Latosol, A moderate and clayey texture. The variation of volumetric water content of soil in these plots was assessed in layers of 0 to 0.20 m and 0.20 to 0.40 m deep. The experimental treatments consisted of covering the soil with quantities of sugarcane straw equivalent to 0 and 1.5 kg.m-2 (0 and 1.5x104 kg.ha-1), the first representing the condition without straw and the second condition with straw . The results collected in the 0-0.20 m layer showed that during the study period there was a decrease in soil water content of 0.103% per day provided with straw and 0.223% per day without straw, or more than double the water loss recorded previously. When it was considered the soil layer of 0.20-0.40 m, the decrease in soil water content was much lower than that of the previous situation, the order of 0.116% per day provided with straw and 0.159% per day without straw. An important point to note is that the treatments used in the experiment had a decisive influence on the direction of water movement in the soil.

Reação do trigo à Magnaporthe grisea nos diferentes estádios de desenvolvimento

The blast of wheat (Triticum aestivum) was first reported in the State of Parana in 1986 and has now spread to all the major wheat growing areas of Brazil. The relation between leaf and neck blast resistance was studied utilizing three isolates and 15 wheat varieties. The relationship between incidence of blast in wheat spikes and infection of harvested seeds was examined using inoculation tests with three fungal isolates on five wheat cultivars. The varieties showing susceptible reaction at seedling stage were also susceptible to spike infection. The BH1146 was the sole variety resistant at seedling stage, which subsequently produced a significantly lower the incidence and severity of blast. A high positive correlation was observed between incidence and severity of diseased heads. The percentage of infected seeds was less in varieties exhibiting a resistant reaction to spike infection than in susceptible varieties.

Toxicidade de flúor em cultivares de milho em área próxima a uma indústria cerâmica, Araras (SP)

The emission of fluoride gases, particles or fluoridric acid is commonly observed in industries that submit terrigenous materials to high temperatures, such as in the ceramic industry. Unusual abnormalities in leaves of adult plants that have been suspected to be fluorine toxicity have been observed in corn experiments carried out in the Center of Agricultural Sciences of the Federal University of Sao Carlos, Araras, SP, Brazil. The symptoms in the corn leaves started as discolouring of internerval cells of completed developed leaves followed by marginal burning of its tips. The objectives of this work was to evaluate the amount of fluorine (F) in corn leaves with injury symptoms, probably from airborne fluorides nearby a ceramic industry, and to verify differences among corn cultivars for the symptoms severity. Leaf analysis in samples collected in corn plants growing 350 and 1.000 m far from a ceramic industry confirmed fluorine concentration as high as four times the normal, ranging from 126 to 160 mg kg-1. Although the genotypes in those two experimental fields showed distinct reactions, it was not possible to correlate any reduction in production with severity of symptoms.

Comparação entre métodos de avaliação de transmissão de Pyricularia grisea através de sementes em triticale

Methods to examine transmission of Pyricularia grisea from seeds to seedlings of triticale Triticale (X. triticosecale ) is the most recent host of Magnaporthe grisea (Pyricularia grisea), the causal agent of blast, in Sao Paulo state. Severe yield losses occurred in large areas in the southern part of the state in 2001. It is speculated that seed borne infection played a vital role in the outbreak and dissemination of this disease. Nevertheless, transmission of disease from seeds to seedlings is still a matter of controversy, in both rice (Oryza sativa) bl ast and wheat (Triticum aestivum) blast. One reason for this debate may be associated with the method used in those studies. The present work was designed to examine the seed borne transmission of P. grisea from seeds to seedlings in triticale under different methods using 100% infected seeds and controlled temperature of 21 °C and 12 h cycles of light. The treatments were as followed: a) seeding in sterilized soil; b) moist but not flooded seeding in sterilized soil; c) seeding in water-agar media; d) seeding in filter paper. The treatments were arranged in a randomized block design with four replications. Transmission of P. grisea from seeds to seedlings was found in all methods with two types of symptoms: death of seedlings and symptoms on leaves with no death. The rate of transmission of these symptoms was similar in all methods, suggesting that any of these methods could be used. Healthy seedlings with no visible blast symptoms emerged from infected seeds in all methods.

Combinação de métodos paramétricos e não-paramétricos na análise de estabilidade de cultivares de cana-de-açúcar

Resumo€Œ€A presenca e a magnitude da interacao genotipoŒambiente sao fatores que determinam odesempenho de cultivares nos diversos ambientes de producao. A€forma de teste e interpretacao dessainteracao tem sido muito discutida na literatura agronomica, e vAErios mOtodos tŒm sido propostos. Oobjetivo deste trabalho foi testar uma combinacao de mOtodos paramOtricos e nao-paramOtricos paraavaliacao da interacao genotipoŒambiente de forma simples e fAEcil. Foram utilizados os resultadosexperimentais de trŒs grupos de cultivares de cana-de-acœcar, de acordo com suas caracteristicas dematuracao (precoce, mOdia e tardia), em mOdia de trŒs cortes, em cinco locais da regiao Oeste do Estadode Sao Paulo. Os€testes utilizados, alOm de simples, permitiram indicar as melhores cultivares paraaquela regiao e para cada Opoca de colheita, e confirmaram, atravOs de modelos probabilisticos, asrecomendacies anteriormente realizadas pelos melhoristas.Termos para indexacao:

Análise da segregação de avirulência de Magnaporthe grisea do trigo

A segregacao de avirulencia entre progenies de cruzamento entre isolados de Magnaporthe grisea provenientes de trigo (Triticum aestivum) foi estudada utilizando cinco variedades de trigo. A populacao segregante desse estudo foi formada por 37 progenies resultantes do cruzamento entre dois isolados de campo que diferiram na reacao de avirulencia/virulencia a essas variedades. Os resultados obtidos mostraram que para as variedades CNT 8, BR 17 e OR 1 a relacao avirulencia/virulencia foi de 1:1, demonstrando segregacao de um gene de avirulencia, que foi diferente para cada uma das variedades. A segregacao observada para as variedades BR 31 e Iapar 3 foi de 1:3 avirulencia/virulencia indicando segregacao de um gene de avirulencia e do supressor desse gene de avirulencia. Alem disso, a recombinacao sexual entre isolados de M. grisea em condicoes de laboratorio possibilitou produzir isolados virulentos a todas as variedades podendo ser uma das causas para a quebra de resistencia de variedades resistentes.

Effect of the spontaneous fermentation and the ageing on the chemo-sensory quality of Brazilian organic cachaça

This study verified the effect of the spontaneous fermentation/natural ferment (NF) on the chemo-sensory quality of cachaca, comparing to the commercial ferment (CF). The effect of ageing (maturation) was also analysed in the beverage. Microbiological analysis (plating on selective media for total/wild yeast and bacteria counting) and physico-chemical analysis (pH, acidity and soluble solids) were performed in the samples of the must and the ferment collected during three cycles of fermentation in a semi-industrial scale. Samples of cachaca were stored in 5-L oak containers for 45 days, subsequently analyzing the physico-chemical characteristics (pH, acidity, alcohol content, copper and secondary compounds) and sensory acceptability (aroma, flavour, colour, body and global impression). The fermentation with NF showed higher number of wild yeasts; however there was no difference in the number of bacteria comparing to CF. An intense acidification occurred during the preparation of NF, which was also observed in the initial cycles of fermentation, but decreased afterwards. Greater alterations in cachaca composition were found to be more exclusively related to the maturation than to the type of ferment, except for the acidity. However, there was a significant loss of aroma, flavour and global impression after maturation but only in cachaca produced with the CF. The results revealed a strong interaction between ferment and maturation of the beverage, suggesting that substances produced by the microorganisms from different inocula during fermentation reacted differently with the wood components of the barrels influencing the sensory attributes.