Tolerance level of green seed in soybean seed lots after storage

The occurrence of green soybean seed due to forced maturation or premature plant death caused by drought or foliar and/or root diseases has been common in several Brazilian production areas. Physiological quality of seed lots with green seed may have their germination and vigor potentials affected and therefore discarded by the grain industry. The objective of this experiment was to determine the maximum tolerated level of green seed in soybean seed lots, which is information of major importance for seed producers when taking the decision whether to sell these lots. Soybean seed of the cultivars CD 206, produced in Ubirata, Parana, and ‘FMT Tucunare,’ produced in Alto Garças, Mato Grosso, were used in the study. Green seed and yellow seed of both cultivars were mixed in the following proportions: 0%, 3%, 6%, 9%, 12%, 15%, 20%, 30%, 40%, 50%, 75% and 100%. Seed quality was evaluated by the germination, accelerated aging, tetrazolium and electrical conductivity tests. The contents of a, b and total chlorophyll in the seed were also determined. A complete randomized block design in a factorial scheme (two cultivars x 12 levels of green seed) was used. Seed quality was negatively affected and chlorophyll contents incremented with the increase in the percentage of green seed. Seed germination, viability and vigor, measured by the accelerated aging test, were not reduced with levels of up to 3% green seed, for both cultivars. Levels above 6% green seed significantly reduced the quality of the seed. The quality of seed lots with 9% or more green seed was significantly reduced to the point that their commercialization is not recommended.

Respiratory activity for the differentiation of vigor on soybean seeds lots

Currently, the highest interest with respect to the assessment of seed physiological quality is to obtain reliable results in a relatively short period of time. This initiative allows for prompt decisions during different phases of seed production primarily after physiological maturity. This research was performed to verify the efficiency and rapidity of the method of Pettenkofer to determine the respiratory activity and to differentiate vigor levels of soybean seed lots. Three lots of soybean seeds cv. 8000 were used. Seed performance was determined by respiratory activity, compared to the following tests: standard germination, germination first count, electrical conductivity, seedling emergence, seedling shoot and root length and total dry mass. Results ranked seed lots according to defferences in physiological quality. Seed imbibition and conditioning period in Pettenkofer's equipment were enough to detect differences in vigor among seed lots, showing that the determination of the respiratory activity is a promising procedure to identify differences in vigor levels among soybean seed lots.

Radiographic analysis in castor bean seeds (Ricinus communis L.)

Castor bean cropping has great social and economic value, but its production has been affected by factors such as low quality seeds used for sowing. The quick and precise evaluation of seed quality by x-ray test is known as an effective method to evaluate seed lots, but little is known about the interpretation between of the type of radiographic image and the seed quality correlation. The potential of x-ray analysis as a marker of seed physiological quality and as an initial process for the implementation of the use of computer-assisted image analysis was investigated using castor bean seeds of the different cultivars. The seeds were classified according to internal morphology visualized in the radiography and subjected to the germination test, emergency and seedling growth rate. It was possible to identify the different types of internal tissues, morphological and physical damage in castor bean seeds using the x-ray test. Tissues generating translucent images, embryo deformation, or tissues with less than 50% of endosperm reserves or spotted, negatively affected the physiological potential of the seed lots. Radiographic analysis is effective as an instrument to improve castor bean seed lot quality. This non destructive analysis allows the prediction of seedling performance and enabled the selection of high-quality seeds under the standards of a sustainable and precision agriculture

Using Tomato Analyzer software to determine embryo size in x-rayed seeds

A primary interest of image analysis of X-rayed seeds is to identify whether the extent of fill in the embryo cavity is associated with to seed physiological quality. The objective of this research was to verify the accuracy of the freely available Tomato Analyzer (TA) software developed at The Ohio State University to determine the ratio of embryo size over total seed area. Seeds of pumpkin, watermelon, cucumber and cotton were X-rayed and analyzed by the software which defines seed and embryo boundaries and automatically generates numerical values to quantify that ratio. Results showed that the TA has the sensitivity to evaluate the extent of embryo growth within the cucurbits and cotton seeds and is a promising alternative for this assessment in other seed species.

Storage of 'Swingle' citrumelo seeds in different maturation stages subjected to fungicide treatment

The establishment of citrus orchards with rootstocks from seed with a low physiological quality has been a recurring problem. Low quality seeds directly affect both the final stand and the time required for seedling production. The irregular maturation of fruits, seed recalcitrance, and the high incidence of fungi, make long term storage difficult, even at low temperatures. This study evaluated the storage potential and the use of fungicide treatments on 'Swingle' citrumelo seeds extracted from fruits collected at two maturation stages, green or ripe. The seeds were subjected to a thermal treatment, treated with Derosal, Thiram or Tecto+Captan fungicides, packaged in impermeable polyethylene bags and stored in a cold chamber for nine months. Every three months, the physiological and sanitary qualities of the seeds were evaluated from germination and sanitary tests and also from enzyme profiles. Seeds from green fruits deteriorated less than those from mature fruits; deterioration increased up to nine months of storage; treatment with the Tecto+Captan mixture gave effective pathogen control and maintained seed quality during storage. The germination of the green and ripe seeds is satisfactory (70%) after three months storage.

Partial characterization of genes from the embryonic axis of Melanoxylon brauna Schott. (Leguminosae-Caesalpinioideae) seeds

The objective of this study was to partially characterize some genes involved in the desiccation tolerance of the embryonic axis of Melanoxylon brauna seeds subjected, or not, to oven fast-drying. Seeds were initially dried rapidly in an oven at 40 ºC, 50 ºC, 60 ºC, 70 ºC, and 80 °C, for 24, 48 and 72 h and then subjected to germination tests and moisture content determination. Degenerate primers were designed for 19 genes. The CDNA was used as a template for PCR amplifications using the degenerate primers, and the PCR products obtained were purified, cloned and sequenced. The seeds showed a gradual reduction in percent germination with increasing temperature and drying time. Nucleotide sequences of the cloned fragments related to genes CAT1, SPS1, Abi5, Transk and PM25 were obtained. The similarity analysis with the sequences deposited in databases revealed similarities with genes CAT1, SPS1, Transk and PM25 from other plant species. The nucleotide sequences obtained from the respective genes will be used for designing specific primers for gene expression analyses during seed germination in order to understand the causes for loss of physiological quality of Melanoxylon brauna seeds.

Performance of lowland rice seeds coated with dolomitic limestone and aluminum silicate

The objective of this study was to evaluate the performance of seeds of two cultivars of lowland rice (Oryza sativa L.), coated with dolomitic limestone and aluminum silicate. It was used a completely randomized experimental design, with the treatments arranged in a 4 X 2 factorial scheme [4 treatments: dolomitic limestone; dolomitic limestone + aluminum silicate; aluminum silicate, at the dosages of 50 g/100 kg of seeds; and control (without the products) X 2 cultivars: IRGA424 and IRGA 422 CL], totaling eight treatments with four replications each. The variables analyzed were: fresh and dry weights of aerial biomass; plant height; leaf area at 10, 20, and 30 days after emergence (DAE). The physiological quality of seeds was also assessed using tests of: seed emergence; first count of germination; emergence speed index; and field emergence. It was concluded that the coating of rice seeds with dolomitic limestone and aluminum silicate does not affect seed germination and field seedling emergence. Aluminum silicate used via seed coating on cultivar IRGA 424 promoted greater leaf area, after 20 DAE. The dolomitic limestone and the aluminum silicate used via seed coating generated plants with larger dry biomass, after 20 DAE, for the cultivar IRGA 422 CL.

Influence of lignin content in soybean seed coat on the incidence of the storage fungus Aspergillus flavus

Seed quality may be affected by several factors, including permeability, color, and lignin content in the seed coat. This study aimed at evaluating influence of lignin content in the tegument of seed samples of six different soybean cultivars, in which half of each sample was inoculated with the fungus Aspergillus flavus, on the physical and physiological quality, and on the seed health, during 180 days storage period, under cold chamber with controlled conditions of temperature and RH. For that, at each interval of 60 days, samples were removed, and the physiological quality of these seeds was assessed by means of moisture and lignin contents; and by tests of seed health, germination, and electrical conductivity. The moisture content of seeds remained constant during all storage period. In the seed health test, it was found that inoculation was efficient, once the minimum incidence of the fungus in the inoculated seeds was 85%. In the germination test, there was a trend of reduction on percentage germination with the increase in storage period. However, there was an increase on electrical conductivity of seeds assessed. It was concluded that there is no interference of the lignin content in the seed coat on the resistance to infection by the fungus Aspergillus flavus, even after seed storage for a period of 180 days.

Detection of adventitious presence of genetically modified seeds in lots of non transgenic soybean

The difficulty on identifying, lack of segregation systems and absence of suitable standards for coexistence of non trangenic and transgenic soybean are contributing for contaminations that occur during productive system. The objective of this study was to evaluate the efficiency of two methods for detecting mixtures of seeds genetically modified (GM) into samples of non-GM soybean, in a way that seed lots can be assessed within the standards established by seed legislation. Two sizes of soybean samples (200 and 400 seeds), cv. BRSMG 810C (non-GM) and BRSMG 850GRR (GM), were assessed with four contamination levels (addition of GM seeds, for obtaining 0.0%, 0.5%, 1.0%, and 1.5% contamination), and two detection methods: immunoassay of lateral flux (ILF) and bioassay (pre-imbibition into 0.6% herbicide solution; 25 ºC; 16 h). The bioassay is efficient in detecting presence of GM seeds in seed samples of non-GM soybean, even for contamination lower than 1.0%, provided that seeds have high physiological quality. The ILF was positive, detecting the presence of target protein in contaminated samples, indicating test effectiveness. There was significant correlation between the two detection methods (r = 0.82; p < 0.0001). Sample size did not influence efficiency of the two methods in detecting presence of GM seeds.

Produção e qualidade fisiológica de sementes de soja avaliadas na semeadura de inverno

O cultivo da soja fora da época convencional pode ser uma alternativa de rotação de cultura além de proporcionar sementes de melhor qualidade fisiológica, que podem ser utilizadas na semeadura da próxima safra diminuindo o período de armazenamento. O trabalho de pesquisa teve por objetivo avaliar o comportamento de sete cultivares de soja, em três densidades populacionais, quanto ao porte e altura de inserção da primeira vagem, assim como quanto à produção e qualidade fisiológica das sementes, semeadas no período de inverno, na região de Selvíria-MS. O delineamento experimental foi em blocos casualizados, com quatro repetições, dispostos em esquema fatorial 7 ×3. Os tratamentos constaram de sete cultivares (IAC-16, IAC-Foscarin 31, FT-2, IAC-17, IAC-8, Doko e FT-Cristalina) e três densidades de plantas (300, 400 e 500 mil plantas ha-1). O ciclo da soja foi reduzido no cultivo de inverno, principalmente nos cultivares considerados tardios. O fotoperíodo no cultivo de inverno reduziu o período entre o florescimento e a maturação. O cultivar IAC-8 foi o menos sensível ao fotoperíodo, possuindo maturação em época semelhante aos cultivares tardios, e apresentou as melhores características agronômicas para o cultivo no período de inverno. É aconselhável o aumento de densidade de semeadura quando do uso de cultivares precoces em cultivos de inverno. Não é aconselhável armazenar sementes em condições ambientes, principalmente com valores de germinação próximo ao limite inferior desejável (80%).

Adequação do teste de condutividade elétrica para determinar a qualidade fisiológica de sementes de jacarandá-da-bahia (Dalbergia nigra (Vell.) Fr.All. ex Benth.)

Para testar o efeito da temperatura e do tempo de embebição nos valores de condutividade elétrica e verificar sua aplicabilidade para determinar a qualidade fisiológica de sementes de Dalbergia nigra (jacarandá-da-bahia), foram utilizadas sementes colhidos em três anos (lote I _ 1998; lote II _ 1997 e lote III - 1994). Inicialmente determinou-se o teor de água e depois conduziu-se os testes de germinação em laboratório e viveiro, utilizando-se quatro repetições de 25 sementes. Para estudar a condutividade elétrica (CE) foram utilizadas quatro repetições de 50 sementes. Cada subamostra foi colocada em recipiente contendo 75ml de água deionizada, embebidas por 6, 12, 18, 24, 30 e 36 horas, a 20, 25 e 30ºC. Sementes do lote II apresentaram maiores valores na primeira contagem da germinação, diferindo significativamente dos demais lotes. O lote III apresentou qualidade inferior. Com o aumento do período e da temperatura de embebição ocorreu aumento nos valores de CE das sementes dos três lotes. O lote III mostrou qualidade fisiológica inferior a dos lotes I e II, que apresentaram valores mais elevados de CE. Não houve diferenciação entre os lotes I e II. Concluiu-se que o teste de CE foi eficiente para diferenciar os lotes de sementes de Dalbergia nigra, com alto grau de associação com o teste de germinação.

Efeito do número de sementes e do volume de água na condutividade elétrica de sementes de Dalbergia nigra (Vell.) Fr.All. ex Benth.

O presente trabalho teve como objetivos verificar o efeito do número de sementes e do volume de água utilizada no teste de condutividade elétrica (CE) para avaliar o vigor de três lotes de sementes de Dalbergia nigra (jacarandá-da-bahia) e correlacionar esses resultados com os dados de germinação em laboratório e em viveiro. Os testes de germinação em laboratório e viveiro foram conduzidos com quatro repetições de 25 sementes. O teste de CE foi realizado com 25, 50 e 75 sementes embebidas a 75, 100 e 125ml de água, por diferentes períodos. A porcentagem de germinação e de plântulas normais em laboratório, indicaram o lote III como de qualidade inferior aos lotes I e II. A primeira contagem da germinação e o índice de velocidade de germinação em laboratório e a emergência, índice de velocidade de emergência e porcentagem de plântulas normais em viveiro identificaram o lote II como superior ao lote I e o III como inferior. A CE diminui com o aumento do volume de água e aumentou com o período de embebição. A diferenciação dos lotes foi mais eficiente, quando se utilizou 75ml de água deionizada e amostras de 50 sementes com pelo menos 36 horas de embebição, com valores de CE menores nos lotes I e II do que no lote II. Os coeficientes de correlação simples entre a CE e as demais características avaliadas, em laboratório e viveiro, foram elevados e significativos, evidenciando alta associação entre os mesmos. Assim, pode-se recomendar que o teste de CE seja conduzido a 25ºC, com amostras de 50 sementes embebidas em 75ml de água deionizada, por períodos iguais ou superiores a 36 horas de embebição, para determinar a qualidade fisiológica de lotes de sementes de jacarandá-da-bahia.

Testes bioquímicos para avaliação do vigor em sementes de Mimosa caesalpiniaefolia Benth

Mimosa caesalpiniaefolia Benth. is a forest species of the Mimosaceae family, recommended for recovery of degraded areas. The evaluation of vigor by biochemical tests have been an important tool in the control of seed quality programs, and the electrical conductivity and potassium leaching the most efficient in the verifying the physiological potential. The objective, therefore, to adjust the methodology of the electrical conductivity test for seeds of M. caesalpiniaefolia, for then compare the efficiency of this test with the potassium in the evaluation of seed vigor of different lots of seeds M. caesalpiniaefolia. To test the adequacy of the electrical conductivity were used different combinations of temperatures , 25 °C and 30 ºC, number of seeds , 25 and 50, periods of imbibition , 4 , 8 , 12 , 16 and 24 hours , and volumes deionized water, 50 mL and 75mL. For potassium leaching test, which was conducted from the results achieved by the methodology of the adequacy of the electrical conductivity test, to compare the efficiency of both tests , in the classification of seeds at different levels of vigor, and the period 4 hours also evaluated because the potassium leaching test can be more efficient in the shortest time . The best combination obtained in experiment of electrical conductivity is 25 seeds soaked in 50 mL deionized or distilled water for 8 hours at a temperature of 30 ° C. Data were subjected to analysis of variance, the means were compared with each other by F tests and Tukey at 5 % probability, and when necessary polynomial regression analysis was performed. The electrical conductivity test performed at period eight hour proved to be more efficient in the separation of seed lots M. caesalpiniaefolia at different levels of vigor compared to the potassium test

Qualidade física e fisiológica de sementes da leguminosa forrageira Macrotyloma axillare cv. Java

É de interesse prático, quando se dispõe de diferentes lotes de sementes, conhecer a qualidade fisiológica intrínseca a cada um. Objetivou-se determinar a qualidade fisiológica de lotes de sementes da leguminosa forrageira tropical, Macrotyloma axillare cv. Java, com utilização de diferentes metodologias para realização dos testes germinação e vigor. Determinou-se a pureza física dos lotes, o peso de mil sementes, a germinação com e sem escarificação (TG) e o vigor (índice de velocidade de germinação (IVG), primeira contagem, envelhecimento acelerado e condutividade elétrica) de três lotes de sementes. Diferenças na qualidade fisiológica inicial de sementes escarificadas foram observadas pelo teste de germinação. Pelos resultados dos testes de primeira contagem e IVG não foi possível detectar diferenças na qualidade fisiológica das sementes; o envelhecimento acelerado das sementes escarificadas pode ser realizado a 41º C por 72 horas ou a 45º C por 48 horas; o teste de condutividade elétrica mostrou-se adequado para diferenciar os lotes, a partir de 48 horas de embebição.

Desempenho de sementes de algodão tratadas quimicamente e armazenadas

Considerando que o armazenamento desempenha papel decisivo na manutenção da qualidade da semente, desenvolveu-se este trabalho com o objetivo de avaliar a qualidade fisiológica e fitossanitária de sementes de algodão, tratadas quimicamente e armazenadas por doze meses. Foram utilizados dois lotes de sementes de algodão cv. DeltaPine-AC90, deslintados quimicamente, que foram submetidos aos tratamentos fungicidas e inseticidas: testemunha; Disulfoton + Carboxin + Thiram; Carbofuran + Carboxin + Thiram; Imidacloprid + Tolylfluanid + Pencycuron. As sementes foram armazenadas em armazém sem controle de temperatura e umidade relativa do ar. Foram retiradas amostras de sementes no início do armazenamento e a cada dois meses e avaliadas quanto ao teor de água, à porcentagem de germinação, ao vigor (testes de envelhecimento acelerado e de germinação à baixa temperatura), à sanidade e à emergência das plântulas. O delineamento utilizado foi o inteiramente casualizado, em esquema fatorial, com quatro repetições. Verificou-se redução da germinação e do vigor de sementes em função do armazenamento. A redução da qualidade fisiológica associou-se com o aumento na ocorrência de Aspergillus sp. e Penicillium sp. nas sementes. A manutenção da qualidade de sementes de algodão foi obtida até o oitavo mês de armazenagem, podendo-se concluir que: a eficiência do tratamento químico de sementes de algodão depende da combinação de produtos utilizados; não se deve tratar com fungicida sementes de algodão com baixo nível de vigor; a ocorrência dos fungos Aspergillus sp. e Penicillium sp. aumentou com o período de armazenamento nas sementes sem tratamento e que a manutenção da qualidade de sementes de algodão para comercialização depende da sua qualidade inicial e do período de armazenamento.