Maria Amelia dos Santos

Isolamento e avaliação da atividade nematicida de constituintes químicos de Mucuna cinerea contra Meloidogyne incognita e Heterodera glycines

Phytochemical investigation of the aerial parts and roots of Mucuna cinerea led to the isolation of a mixture of fatty acids, triacylglicerols, b-sitosterol, stigmasterol, stigmasterol glucoside, daucosterol, asperglaucide (4) and the isoflavonoids prunetin (1), genistein (2), medicarpin (3), daidzein (5), 7-O-a-glycopiranosyl daidzein (6). An in vitro bioassay was carried out with compounds 1-4, at the concentration of 50 and 5 mg mL-1 against the phytonematodes M. incognita and H. glycines. Although the four compounds showed some nematocidal property, the most active was (1), causing 70% mortality of M. incognita at the concentration of 50 mg mL-1.

Genetic variability among and within races of Heterodera glycines Ichinohe assessed by RAPD markers.

Heterodera glycines Ichinohe, the soybean cyst nematode (SCN) was detected in Brazil in 1992 and since then it has been causing losses to Brazilian soybean crop yields. SCN populations have great genetic diversity which makes it difficult to manage this disease. The objectives of this research were to investigate the genetic variation of 16 SCN populations sampled in middle western and southeastern Brazil, utilizing random amplified polymorphic DNA (RAPD) techniques, and to establish useful and specific RAPD markers for SCN race 3. RAPD markers demonstrated genetic variability among and within SCN populations, and they could be used for monitoring nematode population dynamics. The OPA-07 primer was a reliable molecular marker for race 3, while electrophoretic profile analysis of DNA fragments amplified with OPA-10 primer detected slight variation within those populations identified as race 3. The SCN population from Chapadao do Ceu, GO - sample 2 - was the most genetically distant from the other populations.

Efeito do silicato de cálcio e da autoclavagem na supressividade e na conducividade de dois solos à Rhizoctonia solani

The effect of calcium silicate slag and soil sterilization on the natural suppressiveness of a Typic Acrustox (clay Dark Red Latosol ¾ LEa) and the natural conduciveness of an Oxic Haplustoll (TRe) to Rhizoctonia solani were studied under greenhouse conditions. The experimental design was a three-replicate completely randomized one, with 2 x 3 x 2 factorial combination of the following treatments: two soil kinds (LEa and TRe, collected at 0-20 cm layer); three treatments with and without soil sterilization, calcium silicate slag and nontreated control; and uninfested and infested with R. solani. Each soil material was infested previously with 800 mg of the inoculum per kg soil. Application of silicate was done mixing 0,63 g of this product with 1 kg each soil material and incubated for 30 days. The application ofsilicate increased the exchangeable Ca2+ and bases amount in both soils. The decrease in the aluminum saturation level from 70 to 19% and the increase in base saturation from 9 to 21% altered significantly the natural suppressiveness of LEa to R. solani. Application of silicate to the TRe had no effect on its conduciveness, for its natural eutrophic character, which is benefic to R. solani development. Sterilization by autoclavation did not influence disease development on bean by R. solani. This suggests that possibly other abiotic factors were responsible for either suppressiveness or conduciveness of these soils.

Soil microbial response to glucose and phosphorus addition under agricultural systems in the Brazilian Cerrado

Conventional tillage (CT) and no-tillage (NT) management systems alter soil nutrient availability and consequently modify soil microbial response to nutrient additions such as carbon (C) and phosphorus (P). The objective of this study is to evaluate microbial response to the addition of C (glucose) and P (Na2HPO4.7H2O) under CT and NT in the brazilian Cerrado. In response to glucose addition, the NT system yielded higher microbial respiration rates and glucose consumption than the CT system. The best microbial response to C addition was after 0 - 12 h incubation in NT and 0 - 24 h in CT. The addition of P produced higher demand under CT than NT. After incubation, biochemical indicators such as microbial respiration, glucose consumption, dehydrogenase activity and metabolic yield confirmed the higher glucose demands under NT and higher phosphorus demands under CT. These results demonstrate that C and P addition alter significantly the microbial response, suggesting that soil microorganisms present nutrient differential demands between CT and NT management systems.

UFUS Riqueza: a new soybean cultivar for the state of Minas Gerais

O lancamento de cultivares tem garantido maior produtividade associada a maior tolerância as adversidades climaticas. UFUS Riqueza apresenta resistencia a deiscencia natural e as doencas: pustula bacteriana, crestamento bacteriano, mancha olho de ra, podridao parda da haste, cancro da haste e necrose da haste e um potencial produtivo alcancando 3,475 kg ha-1, 18 % de oleo e 39 % de proteina nos graos.

UFUS Guarani: new soybean cultivar for the state Minas Gerais

Day by day alternatives in genetic improvement are being been sought to ensure higher crop productivity. UFUS Guarani developed by the Federal University of Uberlandia is resistant to natural dehiscence and to the diseases: Sudden death syndrome (SDS), frogeye leaf spot, downy mildew, bacterial pustule, stem canker and stem necrosis; the potential yield is 3494 kg ha-1, the grain oil content is 18% and protein content 38%.

Sintese e avaliação da atividade nematicida dederivados da piperazina

In the search for new synthetic nematicides, eight piperazine derivatives were prepared. These compounds, and also two commercially available piperazine derivatives and piperazine, were submitted to a biological assay to evaluate their activity against the phytonematodes Meloidogyne incognita and Heterodera glycines. At the concentration of 20 mg mL-1, the compounds caused 3 to 73% mortality of M. incognita and 7 to 58% mortality of H. glycines.