Geri Eduardo Meneghello

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.

Expressão diferencial de isoenzimas durante o processo de germinação de sementes de arroz em grandes profundidades de semeadura

The germination process consists of a complex and regulated group of physiologic and biochemical events that happen in the seed soon after beginning water absorption. The restart of the embryo growth due to water absorption involves the reactivation of many enzymes that will hydrolyze reserve substances, to supply redox potential and energy for germination. Plantlet emergence in monocotyledonous depends, principally, on the sowing depth and other factors such as genetic potential and seed vigor, because the embryo is nurtured by the seed stores along. In this study, isoenzimatic patterns of Esterase (EST), Acid Phosphatase (ACP), Malate Dehydrogenase (MDH), Alcohol Dehydrogenase (ADH) and Glutamate Oxalacetate Transaminase (GOT) were analyzed among germination processes at 20 cm in 34 red rice ecotypes and 5 commercial cultivars with the objective of identifying differential expression variations in the isoenzimatic systems analyzed. The five isoenzimatic systems analyzed showed variations in the enzymatic expression, mainly when compared with the patterns of the dry seed with the developing plantlets. From the results obtained it was concluded that ere is differential expression in the isozyme genes Esterase (EST), Acid Phosphatase (ACP), Malate Dehydrogenase (MDH), Alcohol Dehydrogenase (ADH) and Glutamate Oxalacetate Transaminase (GOT), showing participation in the germination process in rice.

Teste de respiração para avaliar a qualidade fisiológica de sementes de girassol

The increased demand for high quality oilseeds, such as sunflower, has encouraged interest in faster tests to distinguish seed lots, and allow prompt decisions during different stages of seed production, storage, and marketing. The objective of this study was to evaluate the efficiency of the Pettenkofer method for determining respiratory activity, which can be used to differentiate the vigor of different cv. MG2 sunflower seed lots. Besides determining respiratory activity, the germination, electrical conductivity, total dry weight, fresh weight and seedling length were measured. The results permitted the classification of seed lots according to their potential performance. The Pettenkofer apparatus provided an efficient and fast separation of seed lots and the measurement of respiratory activity is promising for identifying differences in the physiological quality of sunflower seeds.

IDENTIFICAÇÃO DO ESTÁDIO ADEQUADO PARA REALIZAÇÃO DE ANÁLISES ISOENZIMÁTICAS NA CARACTERIZAÇÃO DE CULTIVARES DE ARROZ 1

Enzymatic systems commonly used in cultivar characterization are products of gene expression and are, therefore, highly influenced by development stages, the organ from which they are collected and the environment. Usually, these factors are not considered when several enzymatic complexes are used from a single protein extraction, resulting in an inefficient reading and interpretation of the results. This study was carried out to evaluate the adequate stage for protein extraction for each enzymatic complex, when there is a maximum phenotypic expression, to be used in rice isoenzymatic characterization. Two lots, one of high and one of low physiologic quality, for each of the rice varieties El Paso L144, IRGA 417 and EEA 406, were analyzed using the Esterase, Acid Phosphatase, Glutamate Dehydrogenase, Glutamate Oxalacetate Transaminase, and Malate Dehydrogenase analyses. Six development stages (0, 2, 4, 6, 8 and 10 days) were used for protein extraction. Results suggested that each isoenzymatic complex requires an adequate moment for protein extraction; it was not possible to identify a development stage where the maximum phenotypic expression of the Esterase, Acid Phosphatase, Glutamate Dehydrogenase, Glutamate Oxalacetate Transaminase, and Malate Dehydrogenase isoenzymatics complexes presented the same profile; it is not recommended to analyze several isoenzymatics complexes from a single protein extraction; the physiologic quality of EEA 406 seeds affected the Esterase and Glutamate Oxalacetate Transaminase isoenzymatic profiles.

Qualidade fisiológica de sementes de arroz submetidas à radiação gama

The objective of this research was to evaluate the effects of the gamma radiation (Co60) on the physiological quality of rice seeds. The research was carried out through three tests; in the first test rice seeds were irradiated at dosages of 0; 1; 2.5 and 5Gy, while for the second and third tests the seeds were subjected to accelerated aging before being irradiated. For the second test the seeds were divided into wet and dry and both groups subjected to accelerated aging previous to irradiation at dosages of 0; 1; 2.5 and 5Gy. For the third test the seeds were dried after being subjected to accelerated aging, and then irradiated at dosages of 0, 10, 25 and 50Gy. To assess the physiological effects of the gamma radiation, all seeds were tested for germination and their germination speed index recorded. Seedling growth was graded through the measurement of the lengths of the first leaf and seminal root system and total seedling dry weight, across all tests. The enzymatic activity of acid phosphatase and alpha-amylase was measured on dry seeds from the second test. The results from all tests indicate that the applied gamma radiation dosages did not cause any changes to the physiological quality of rice seeds.

Influência dos diferentes períodos de colheita na expressão de isoenzimas em sementes de cevada

O objetivo foi avaliar os padroes isoenzimaticos de Esterase (EST - EC 3.1.1.1), Fosfatase Acida (ACP - EC 3.1.3.2), Malato Desidrogenase (MDH - EC 1.1.1.37), Alcool Deshidrogenase (ADH - EC 1.1.1.1) e Glutamato Oxalacetato Transaminase (GOT - EC 2.6.1.1), em sementes e plântulas de dois cultivares de cevada (MN 721 e Scarlett). As sementes foram fornecidas pela empresa Westermann, localizada no municipio de Piratini, Rio Grande do Sul, onde foi realizado o cultivo da cevada em 2007. Foram colhidas em tres epocas com diferentes percentuais de umidade, secas a 13% de umidade e armazenadas em câmara fria. Os cinco sistemas isoenzimaticos analisados apresentaram variacoes na expressao, principalmente quando comparados entre sementes e plântulas. Concluiu-se que ha variacao no padrao de expressao das enzimas EST, ACP, MDH, ADH e GOT entre sementes e plântulas. A expressao das enzimas EST e GOT foi pouco e muito influenciada pela epoca de colheita, respectivamente.

Avaliação de genótipos de milho para semeadura precoce sob influência de baixa temperatura

Corn (Zea mays L.) is a characteristic plant of tropical climates that requires heat and humidity to produce satisfactorily and to provide compensatory incomes. Several factors can compromise seed germination and plant emergence in the field, and it is important to consider sowing in soils with low temperatures. In regions where low temperature conditions predominate, the use of more tolerant seeds to this stress condition would be important. Corn seeds present genetic variability for germination at low temperatures. The objective of this study was to classify corn genotypes for germination at low soil temperatures. Sixteen 16 genotypes from the breeding corn program of the company KSP Sementes and Pesquisas Ltda. were evaluated, 10 lines at different endogamic stages, six cross pollination populations and three 3 single commercial hybrids, recommended for earlier sowing in southern Brazil. The physiological quality was evaluated by the tests of germination, first count of germination, plant growth, dry matter, shoot and root area AT 25°C and 10°C. The eletroforetic patterns of the isoenzimatic systems of the acid phosphatase, esterase and peroxydase were also evaluated. The tested materials could be ranked from the results for tolerance to low temperatures, showing that there is variability between them and the possibility of using the best performers in earlier sowings in southern Brazil.

Resposta fisiológica de sementes de algodão tratadas com tiametoxam sob estresse térmico

This study aimed to verify the effect of seeds treated with thiamethoxam on the emergence, growth and chlorophyll content of seedlings of two cotton cultivars subjected to abiotic stress. The seeds used were from the DeltaOpal and NuOpal cultivars, each one represented by three lots, previously subjected to determination of moisture content, germination and vigor (low temperature germination). Then, the seeds from each lot, treated with thiamethoxam at a dose of 600 mL of product per 100 kg-1 seed or not, were exposed to temperature (18, 25 and 35 °C) and water availability (40, 60 and 80%) stress conditions. The emergence percentage, the root and shoot length, and the chlorophyll content were evaluated. The growth of cotton seedlings from the DeltaOpal and NuOpal cultivars, subjected to low temperature conditions and water availability of 40 to 60%, is favored by seed treatment with thiamethoxam. Seed treatment with thiamethoxam increases chlorophyll content during the development of cotton plants.

Thiamethoxam: An Inseticide that Improve Seed Rice Germination at Low Temperature

Researches were made to establish the activity of the active ingredient on the physiology of the plant, when applied the soybean seed treatment. It was observed that seed germination index and seedling vigor were higher than those of plants in plots without seed treatment. It was also found that, under water stress conditions soybean plants from seed treated with thiamethoxam showed better growth, such as increased length and root volume, faster ini‐ tial development, higher leaf area, height, number of pods and green colored more intense.