Fernando Augusto Henning

Alterações fisiológicas em sementes de arroz expostas ao frio na fase de germinação

Cold is one of the main problems for rice cultivation in Rio Grande do Sul because the vast majority of cultivars in use are of tropical origin. The occurrence of low temperatures combined with the susceptibility of the materials used can cause serious damage to the establishment of the crop reducing the plant stand. The objective of this study was to evaluate the physiological changes in different rice cultivars, when exposed to low temperature during germination. Seeds from four cultivars, BRS Agrisul, BRS Chui, Lemont and Oro were used and evaluated regarding low temperature tolerance by the cold test. To evaluate the physiological changes, isoenzyme analyses of alcohol dehydrogenase and esterase were performed at temperatures of 25 oC (ideal for germination) and 13 oC (low temperature). The other characteristics evaluated were germination, germination speed, coleoptile length and dry weight at 25 oC and 13 oC. According to cold test results, seeds of the Lemont and Oro cultivars presented better tolerance to the low temperature. In the isoenzyme analysis, the cold caused an increase in the expression of the isoenzyme alcohol dehydrogenase and reduction in the esterase isoenzyme expression. For the other ratings, the cold caused damage to all the characteristics evaluated, especially in the BRS Agrisul and BRS Chui cultivars.

Composição química e mobilização de reservas em sementes de soja de alto e baixo vigor

CHEMICAL COMPOSITION AND RESERVE MOBILIZATION IN SOYBEAN SEEDS WITH HIGH AND LOW VIGOR The study of vigour effect on the initial stages of soybean seeds development is important, once it includes the period of crop establishment. Seeds with low vigour may result in reduction of emergence rate and dry matter production, which may affect the crop establishment. The aims of this study were to quantify chemical components and to evaluate the capacity of seed reserve mobilization in germination of soybean seeds with high and low vigour. Three cultivars, BRS 243RR, BRS 246RR and CD 219RR were studied. The characterization of seed vigour was performed by the accelerated aging test. To determine seed chemical composition, soluble sugar, starch and soluble protein were quantified; in addition alpha amylase isoenzyme activity was also evaluated. The capacity of seed reserve mobilization during germination was evaluated by seedling dry matter and length. According to the results of this study, high vigour soybean seeds exhibit higher content of soluble proteins, starch and soluble sugars. Besides, they showed higher capacity of seed reserve mobilization during germination, resulting in a better performance for seedlings development.

Bioprotetores e fungicidas químicos no tratamento de sementes de soja

Several pathogens can damage the soybean seed quality. Seeds treatment offers additional assurance to the establishment of farming at reduced costs, used mainly with the purpose of improving germination in infected seeds, controlling pathogens transmitted by seeds and protecting seeds from soil borne fungi. Significant increase of soybean seed treatment with fungicides demands research on alternative solutions, like bioprotectors, used with the intention of reducing the use of chemical pesticides, risks to operators and possible damages to Bradyrhizobium inoculation. The aim of this research was to evaluate the efficacy of seed treatment with bioprotectors agents and chemical fungicides in soybean emergency and seeds sanity. Biological agents Biotrich (Trichoderma), HFF Turfa Fertil and (Bacillus pumilus) and chemical fungicides carbendazin + thiram, carboxin + thiram and difenoconazole + metalaxyl were tested. Evaluation of products performance was carried out in laboratory, where the seed sanity was evaluated through blotter test, green house, where the plants emergency was evaluated, and in the field, plants emergency and plants height were evaluated. Better results were obtained with chemical fungicides especially benzimidazoles group associated to contact fungicide (thiram). These products promoted an adequate plant stand, even with sowing coinciding with drought periods. According to results obtained in this work, biological protectors do not offer protection to seeds in the soil reducing plant emergency.

Qualidade fisiológica e sanitária de sementes de Feijão-miúdo beneficiadas em mesa gravitacional

The objective of this work was to evaluate the effect of the gravitational table in the sanitary and physiological quality in seeds lots of (Vigna unguiculata (L.) Walp). After the cleanness, seeds of four genotypes (Peanut, Bay, Mosqueado and Preto) had been submitted to the action of the gravity table with discharge divided in three fractions: superior, intermediate and inferior. It is admitted himself as inferior extremity, the situated one in the lowest point of the discharge when considered the lateral inclination of the table and, as superior, the opposing one. Physiological quality of the seeds was evaluated by germination test and vigor (accelerated aging, electric conductivity and cold test). For evaluation of the sanitary quality the blotter test was used. It was observed that the separation of the seeds through the gravitational table provided positive alterations in the physiological and sanitary quality of the lots of beans-small seeds for all the evaluated genotypes, justifying her use in the improvement of seeds of beans-small.

Structural differences between soybean seeds coat with contrasting permeability.

A exposicao das sementes de soja a ciclos alternados de elevada e baixa umidades antes da colheita, provocado pela ocorrencia de chuvas frequentes, orvalho ou as flutuacoes diarias da umidade relativa do ar, resulta na deterioracao por umidade, a qual pode ser apontada como a principal causa para a baixa qualidade das sementes. Alguns trabalhos tem evidenciado a existencia de genotipos de soja contrastantes para qualidade fisiologica de sementes. Tais diferencas podem existir em virtude da total ou parcial impermeabilidade do tegumento a penetracao de agua, o que torna as sementes menos susceptiveis aos danos mecânicos, as adversidades climaticas e a deterioracao por umidade. O objetivo desse estudo foi avaliar a qualidade fisiologica das sementes dos genotipos de soja CD-202 (tegumento amarelo, permeavel e susceptivel a deterioracao) e TP (tegumento preto, semi-permeavel e resistente a deterioracao) e identificar diferencas estruturais existentes entre os tegumentos desses genotipos. Na determinacao da qualidade fisiologica das sementes utilizaram-se os testes de germinacao e vigor (condutividade eletrica e envelhecimento acelerado). Para avaliacao da estrutura dos tegumentos, foram coletadas sementes de soja em diferentes estadios de desenvolvimento (25, 40 e 55 dias apos a antese). Essas amostras foram encaminhadas ao Laboratorio de Imunologia e Microscopia Eletronica da Embrapa Clima Temperado, onde os tecidos de tegumento foram visualizados em microscopio otico Olympus BX 51 com aumento de 40x, atraves de cortes histologicos na regiao oposta ao hilo. De acordo com os resultados do trabalho, sementes do genotipo TP apresentaram qualidade fisiologica superior em relacao ao genotipo CD-202. Quanto a caracterizacao morfologica, foram detectadas diferencas entre as estruturas dos tegumentos de soja de coloracao preta e amarela, as quais podem estar relacionadas a qualidade de sementes.

cDNA-AFLP na identificação de genes relacionados a qualidade fisiológica

Some studies have reported the existence of contrasting soybean genotypes for seed physiological quality. Differences such as presence of seeds with total or partial impermeability for water absorption through the seedcoat make them less susceptible to mechanical damage, adverse weather and deterioration. The semi-permeable seed coat trait can be used in soybean crop breeding programs to be incorporated in genotypes with high production. However, is necessary to characterize genes involved with the trait. Molecular biology tools, such as the cDNA-AFLP technique, can be used to identify genes involved in seed physiological quality. The objective of this study was to evaluate the efficacy of the cDNA-AFLP technique to obtain gene fragments differently expressed among soybean seedcoats with contrasting permeability. Seeds from two genotypes, CD-202 (susceptible to deterioration and permeable yellow coat) and TP (resistant to deterioration and semi-permeable black coat) were produced in greenhouse under homogeneous conditions. Seeds were harvested at different times (25, 30, 35, 40 e 55 days after anthesis). The total RNA was extracted using Pure Link Plant RNA reagent. The Double Stranded cDNA Synthesis Kit was used to obtain cDNA double strand. The AFLP technique was applied and 64 primer combinations were tested. This tool permitted the identification of 47 gene fragments differently expressed among coats from the two genotypes and was shown to be an efficient alternative to studies related to the identification of genes involved in seed quality.

Qualidade fisiológica, sanitária e análise de isoenzimas de sementes de aveia-preta tratadas com diferentes fungicidas

Black-oat is a rustic grass used as livestock fodder as well as winter green fertilization in crop rotation systems. Low sanitary quality of black oat seeds due to inadequate handling at harvest and in after-harvest phase is one of the limiting factors to production. The objective of this study was to evaluate the performance of a bioprotetor (Trichoderma spp.) and chemical fungicides (Carbendazin + Thiram and Carboxin + Thiram) in the physiological and sanitary quality of black oat seeds and in their enzymatic activities. After the treatment the physiological quality of the seeds was evaluated by germination and vigor tests (speed of emergence and first germination count). The sanitary analysis was carried out by the blotter test. Alcohol desidrogenase, acid fosfatase and esterase activity were evaluated by electrophoresis. Vigour and germination tests showed that seeds treated with chemical fungicides performed better. In the sanitary analysis, the presence of fungi Bipolaris sorokiniana and Fusarium graminearum was observed. The treatment with bioprotetor did not differ statistically from the control, showing higher fungi incidence when compared to the seeds treated with chemical fungicides. In relation to biochemical alterations, the treated seeds and the ones treated with bioprotetor presented an increase in the isoenzymatic activity in all the evaluated enzymes indicating degenerative transformations due to fungi action.

Dissimilaridade genética em população segregante de soja com variabilidade para caracteres morfológicos de semente

The soybean seed coat is a structure associated with seed germination, vigor and longevity. Soybean genotypes show genetic variability regarding the seed coat traits, which can be used in soybean breeding programs. The objectives of this study were: to analyze the genetic similarity of a segregant soybean population for morphological seed traits using morphological and molecular markers (AFLP, RAPD and SSR) and to establish the correlation between the dissimilarity matrices obtained using different marker classes. The population was obtained by crossing between two contrasting soybean genotypes: the cultivar CD 202 (female parent) with a yellow coat, and the genotype TP (male parent) with a black coat. The morphological traits evaluated were coat and hilum colors, hilum spread, pubescence and flower colors. Molecular markers were obtained by AFLP, RAPD and SSR techniques. Based on estimated similarity matrices, dendrograms were developed and the correlations between all matrix pairs and dendrograms estimated. The results showed that AFLP markers are more efficient for accessing the genetic variability of this population. Only the dissimilarity matrix and the dendrogram obtained by AFLP markers showed a positive correlation with the dissimilarity matrix and dendrogram obtained by morphological data.