Thermal studies on protein isolates of white lupin seeds (Lupinus albus)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Genetic diversity of three size classes of seeds of Eucalyptus globulus ssp. globulus

Variation in seed size is often observed in samples of eucalypt seeds and this leads to heterogeneous populations of plants, principally through variation in the early stages of plant development. It follows that samples of seeds more uniform in size could produce more uniform populations of plants. In studies of Eucalyptus globulus ssp. globulus it was of interest to determine whether or not the genetic diversity within a population, through the use of isozyme markers, was altered in the subpopulations developed from seeds of different size classes. A commercial sample of seed was separated by seed size into three subpopulations and the percentage germination and mean fresh weight of the seedlings were determined. Proteins extracted from leaves of the seedlings were separated by electrophoresis and tested for activity of eight different enzymes. These eight enzymes showed activity at 20 loci and mean genetic diversity and fixation index were determined using 13 of these loci. The subpopulation of the smallest seeds contained a greater proportion of abnormal seeds and had a lower percentage germination and plant weight compared to the other subpopulations. No significant differences were found in the number of alleles per locus, percentage of polymorphic loci, mean heterozygosity. The major part of the endogamy, indicated by F statistic, was found within the subpopulations: F-(IS) = 0.518; F-(ST) = 0.010 and F(IT) = 0.523. We conclude that the use of seeds of uniform size will lead to more uniform germination and plant growth without alteration in overall genetic diversity.

Imbibition phases and germination response of Mimosa bimucronata (Fabaceae: Mimosoideae) to water submersion

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Genetic diversity in Egeria densa and E. najas in Jupia Reservoir, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Quinolizidine alkaloids in Ormosia arborea seeds inhibit predation but not hoarding by agoutis (Dasyprocta leporina)

Quinolizidine alkaloids (QAs) are secondary compounds found in seeds of many species of plants, possibly protecting them against pathogens and seed predators. QAs were isolated from Ormosia arborea seeds and bioassayed against red-rumped agoutis (Dasyprocta leporina, Rodentia: Caviomorpha) to verify if they inhibit seed predation and food hoarding (seed dispersal). Three treatments were used: (1) seeds of O. arborea, (2) palatable seeds of Mimusops coriacea (Sapotaceae) treated with MeOH, and (3) seeds of M. coriacea treated with QAs dissolved in MeOH in similar concentration to that present in O. arborea. Palatable seeds were significantly more preyed upon than seeds treated with QAs and Ormosia seeds, but QAs did not influence hoarding behavior. QAs in O. arborea may have a strong effect in avoiding seed predation by rodents, without reducing dispersal.

Bioactive Compounds in Lipid Fractions of Pumpkin (Cucurbita sp) Seeds for Use in Food

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Polyembryony increases embryo and seedling mortality but also enhances seed individual survival in Handroanthus species (Bignoniaceae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Millet seeds mixed with phosphate fertilizers

O tamanho reduzido das sementes de milheto dificulta sua semeadura uniforme, principalmente para os produtores que não possuem semeadoras apropriadas. Assim, a mistura das sementes com os fertilizantes fosfatados vem sendo utilizada para facilitar a semeadura. Entretanto, o período de contato pode provocar prejuízos na germinação e no vigor. Avaliou-se a qualidade fisiológica das sementes de milheto submetidas a diferentes períodos de contato (0, 6, 12, 24, 48, 72, 96 e 120h) com os fertilizantes superfosfato simples (SFS) e superfosfato triplo (SFT), em um experimento em delineamento inteiramente casualizado em esquema fatorial 8x2 (n=4). Os atributos químicos e físicos dos fertilizantes foram previamente determinados. Foi utilizada a proporção de 1 kg de sementes para 2,5 kg de fertilizante. Após manutenção da mistura em saco plástico no laboratório, as sementes foram separadas dos fertilizantes e submetidas à determinação de umidade, germinação, primeira contagem e condutividade elétrica. Paralelamente, na casa de vegetação, em caixas plásticas contendo terra, determinou-se a emergência e o índice de velocidade de emergência, sem e com a manutenção dos fertilizantes. Porque apresentam resíduos ácidos, tanto SFS como SFT afetaram de maneira semelhante e negativamente a germinação e o vigor das sementes de milheto em mistura, na medida em que se aumentou o período de contato.

Seed weight of Xylopia aromatica (Annonaceae): quality evaluation from X-ray and seedling emergence

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Oviposition preference of Bemisia tabaci (Genn.) biotype B (Homoptera: Aleyrodidae) for bean genotypes containing arcelin in the seeds

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Semi-selective culture medium for Curtobacterium flaccumfaciens pv. flaccumfaciens isolation from bean seeds

Curtobacterium wilt has become an important disease of beans in several localities in the country. Its causal agent, Curtobacterium flaccumfacciens pv. flaccumfaciens (Cff), survives and is disseminated through seeds. To date, few studies have been conducted with the objective of developing an effective and low-cost culture medium to isolate this bacterium from bean seeds, for health analysis purposes. Usually, the culture media employed for coryneform bacteria isolation contain specific carbon sources and antimicrobial products not available in the Brazilian market. A culture medium known as MSCFF was developed (peptone - 5 g, meat extract - 3 g, sucrose - 5 g, agar 15 g, skim milk powder* - 5 g. Congo red* - 0.05 g-, chlorothalonil* - 0.01 g, thiophanate methyl* - 0.01 g, nalidixic acid* - 0.01 g, nitrofurantoin* - 0.01 g. oxacillin* 0.001 g, sodium azide* - 0.001 g and distilled water q.s. 1L; *added after autoclaving the basal medium), which has the ability to inhibit growth of a large amount of saprophytic bacteria, but with low supressivity to Cff isolates. The MSCFF medium was highly effective for Cff isolation from naturally infected bean seeds and could be used for routine detection of this bacterium in bean seeds.

Study of seed-germination and etiolation of seedlings in Emilia-sonchifolia (l) dc and Emilia-fosgerbii nicolson (Asteraceae)

The germination of seeds of Emilia sonchifolia (2n) and E. fosgerbii (4n) was analysed and our results indicate that the former present light insensitive seeds and the latter germinated only under continuous white light. The germination of seeds under shade light presented no differences between both species, However under continuous white light, which maintain 70% of Pfr, the velocity of germination was greater in Emilia sonchifolia when compared to Emilia fosbergii, indicating that the threshold of 4n seeds were greater than 2n seeds. The analysis of the fluence response curves for etiolating process indicated that the process presented no differences between both species. The same was observed for the effect of the shade light in the etiolating process.

Curtobacterium flaccumfaciens pv. Flaccumfaciens detection in bean seeds using a semi-selective culture medium

The bacterial wilt caused by Curtobacterium flaccumfaciens pv. flaccumfaciens is currently considered one of the most important bacterial bean disease in Brazil. One of the most effective control methods against this disease is the use of healthy seeds. However, no methods are known that could be routinely used to detect this bacterium in bean seeds under Brazilian condition. The aim of this work was to evaluate qualitative and quantitative detection methods for Curtobacterium flaccumfaciens pv. flaccumfaciens in naturally-infected bean seeds, and the detection of this pathogen in thirty bean seed samples, by sowing onto a semi- selective culture medium the leachate obtained from soaked bean seeds. Both the qualitative and quantitative methods were effective for detecting the presence of the bacteria in the seeds samples analysed. The qualitative method proved more practical for rotine use; of the thirty bean seed samples analyzed by this method, fifty percent were infected with Curtobacterium flaccumfaciens pv. flaccumfaciens.

On the germination and dormancy of dispersal units of Brachiaria decumbens STAPF

The effect of light and temperature on germination of Brachiaria decumbens as well as the action of some dormancy breaking chemicals were tested. Two seed batches stored different times were used. The results show that seeds failed to respond to alternating temperature regimes and different light qualities. Seeds were indifferent to white light at 25 degrees C. KNO3, ethanol and H2SO4 failed to break seed dormancy, whereas KCN and H2O2 partially reduced dormancy of two month stored seeds. The results suggest a metabolic character of dormancy in ''new'' (freshly collected) seeds and confirm the occurence of two types of dormancy in B. decumbens seeds.

Antifungal amides from Piper arboreum and Piper tuberculatum

In continuation of our study of the Piperaceae we have isolated several amides, mainly those bearing isobutyl, pyrrolidine, dihydropyridone and piperidine moieties. Bioactivity-guided fractionation of extracts from leaves of Piper arboreum yielded two new amides, N-[10-(13,14-methylenedioxyphenyl)-7(E),9(Z)-pentadienoyl]-pyrrolidine (1), arboreumine (2) together with the known compounds N-[10-(13,14-methylenedioxyphenyl)-7(E)-pentaenoyl]-pyrrolidine (3) and N-[10-(13,14-methylenedioxyphenyl)-7(L, 9(E)-pentadienoyl]-pyrrolidine (4). Catalytic hydrogenation of 3 yielded the amide iV-[10-(13,14-methylenedioxyphenyl)-pentanoyl]-pyrrolidine (5). We also have isolated six amides (6-11) and two antifungal cinnamoyl derivatives (12, 13) from seeds and leaves of Piper tuberculatum. Compounds 1-11 showed antifungal activity as determined by direct bioautography against Cladosporium sphaerospermum while compounds 3-4 and 6-13 also showed antifungal activity against C. cladosporioides. (C) 2002 Published by Elsevier B.V. Ltd.