Controlled Deterioration Test Research Articles

Teste de deterioração controlada em sementes de maxixe

O potencial fisiológico de sementes, determinado pela germinação e vigor, é diretamente responsável pelo desempenho das sementes em campo, refletindo dessa forma na produtividade de diversas espécies de hortaliças de importância econômica. Diante disso, a pesquisa teve como objetivo estudar a metodologia do teste de deterioração controlada, procurando-se verificar sua eficiência para identificação de diferentes níveis de vigor de lotes de sementes de maxixe (Cucumis anguria L.), cv. Liso. Para tanto, cinco lotes de sementes foram submetidos aos testes de germinação, emergência de plântulas em casa de vegetação, envelhecimento acelerado com solução saturada de NaCl, condutividade elétrica e deterioração controlada (sementes com graus de umidade de 19; 21 e 24%, a 45ºC, durante 24 e 48 horas). A combinação 24% de água/24 h/45ºC no teste de deterioração controlada mostrou-se eficiente para detectar diferenças de vigor entre os lotes de sementes de maxixe.

Testes para monitorar a qualidade fisiológica de sementes de Brachiaria brizantha (A. Rich.) Stapf. durante o armazenamento

O trabalho teve como objetivo avaliar a eficiência dos testes de envelhecimento acelerado e de deterioração controlada para monitorar a qualidade fisiológica de sementes de B. brizantha durante o armazenamento. Três lotes de sementes não escarificadas e escarificadas com H2SO4 concentrado foram acondicionados em embalagem permeável e armazenadas em condições de ambiente no Laboratório de Sementes do DFT/UFV no período de dezembro de 1999 a agosto de 2000. Foram, então, submetidos aos testes de germinação, envelhecimento acelerado a 43ºC/48h e 60h a 100% e 76 % UR, deterioração controlada a 45ºC/24h em sementes com 20 e 24% de umidade e índice de velocidade de emergência de plântulas. As avaliações foram feitas aos 0, 60, 120, 180 e 240 dias de armazenamento. O envelhecimento acelerado conduzido a 43ºC e 100% UR por 48h foi o procedimento mais eficiente para monitorar o comportamento das sementes de B. brizantha durante o armazenamento, fornecendo informações correlacionadas ao índice de velocidade de emergência das plântulas.

Envelhecimento acelerado e deterioração controlada em sementes de amendoim

Pesquisas têm sido desenvolvidas visando determinar os procedimentos para a avaliação de diferenças no potencial fisiológico de lotes de sementes, com destaque aos testes de vigor. O objetivo deste trabalho foi estudar o envelhecimento acelerado e a deterioração controlada para avaliação do vigor de sementes de amendoim (Arachis hypogaea). Quatro lotes de sementes de amendoim da cultivar Tatu foram submetidos ao teste de envelhecimento acelerado, em caixas tipo gerbox, com temperatura de 42ºC ou 43ºC, por 48 horas e 72 horas, com e sem o emprego de solução saturada de NaCl, e ao teste de deterioração controlada, com teor de água de 15% e 20%, a 40ºC ou 45ºC, por 48 horas. O teor de água, a germinação e sanidade das sementes foram determinados. Pelos testes de germinação e de emergência, não houve diferença significativa de desempenho entre os quatro lotes. No teste de envelhecimento acelerado com solução salina, o período de 72 horas a 42ºC é suficiente para avaliar o potencial fisiológico das sementes. No teste de deterioração controlada, a combinação de 15% de teor de água nas sementes e 48 horas em banho maria a 45ºC é eficiente para detectar diferenças de vigor entre os lotes.

Genetic differences in seed longevity of various Arabidopsis mutants

Seeds gradually lose their viability during dry storage. The damage that occurs at the biochemical level can alter the seed physiological status and is affected by the storage conditions of the seeds. Although these environmental conditions controlling loss of viability have been investigated frequently, little information is available on the genetics of seed longevity. Using Arabidopsis mutants in defined developmental or biochemical pathways such as those affected in seed coat composition, seed dormancy, hormone function and control of oxidative stress, we tried to gain insight into the genes and mechanisms controlling viability of stored seeds. Mutations like abscisic acid insensitive3 (abi3) as well as abscisic acid deficient1 (aba1) show reduced longevity, which may be partially related to the seed dormancy phenotype of these mutants. Mutants with seed coat alterations, especially aberrant tests shape (ats), showed a stronger reduction in germination percentage after storage, indicating the importance of a ‘functional’ seed coat for seed longevity. A specific emphasis was placed on mutants affected in dealing with Reactive Oxygen Species (ROS). Because several pathways are involved in protection against ROS and because gene redundancy is a common feature in Arabidopsis, ‘double’ mutants were generated. These ‘double’ mutants and the corresponding single mutants were subjected to a controlled deterioration test (CDT) and a germination assay on hydrogen peroxide (H2O2) after prolonged storage at two relative humidities. CDT and germination on H2O2 affected all genotypes, although it appears that other effects like genetic background are more important than the deficiencies in the ROS scavenging pathway. Explanations for this limited effect of mutations affecting ROS scavenging are discussed.

Analysis of natural allelic variation of Arabidopsis seed germination and seed longevity traits between the accessions Landsberg erecta and Shakdara, using a new recombinant inbred line population.

Quantitative trait loci (QTL) mapping was used to identify loci controlling various aspects of seed longevity during storage and germination. Similar locations for QTLs controlling different traits might be an indication for a common genetic control of such traits. For this analysis we used a new recombinant inbred line population derived from a cross between the accessions Landsberg erecta (Ler) and Shakdara (Sha). A set of 114 F9 recombinant inbred lines was genotyped with 65 polymerase chain reaction-based markers and the phenotypic marker erecta. The traits analyzed were dormancy, speed of germination, seed sugar content, seed germination after a controlled deterioration test, hydrogen peroxide (H2O2) treatment, and on abscisic acid. Furthermore, the effects of heat stress, salt (NaCl) stress, osmotic (mannitol) stress, and natural aging were analyzed. For all traits one or more QTLs were identified, with some QTLs for different traits colocating. The relevance of colocation for mechanisms underlying the various traits is discussed.

Avaliação do vigor de sementes de melão pelo teste de deterioração controlada

O trabalho teve como objetivo determinar a eficiência do teste de deterioração controlada para avaliar o vigor de sementes de melão (Cucumis melo L.). Inicialmente, sementes de quatro lotes do híbrido Golden Mine tiveram o seu teor de água ajustado para 20 e 24%. Foram então submetidas à deterioração controlada em banho Maria, a 45º C, por 24 e 48 horas. Os resultados obtidos foram relacionados aos de germinação, primeira contagem de germinação, germinação a baixa temperatura, emergência de plântulas em solo e comprimento médio de plântula. Os resultados indicaram que a deterioração controlada a 45º C por 48 horas, utilizando-se sementes com grau de umidade de 24%, foi o procedimento mais eficiente para a separação dos lotes em níveis de vigor.

Teste de deterioração controlada para avaliação do vigor de sementes de feijão

O teste de deterioração controlada tem sido utilizado freqüentemente para avaliar o vigor de diversas espécies, podendo ser uma alternativa para avaliação do vigor em sementes de feijão. No entanto, as condições para a realização deste teste ainda não estão completamente definidas. Devido a isto o presente trabalho teve por objetivo determinar as condições mais adequadas para a condução do teste de deterioração controlada em sementes de feijão comparando sua eficiência com o teste de envelhecimento acelerado. Utilizaram-se cinco lotes de sementes de feijão, cultivar Iapar 44, com diferentes qualidades fisiológicas. A qualidade inicial de cada lote de sementes foi avaliada pelos testes de germinação, primeira contagem, envelhecimento acelerado, condutividade elétrica e emergência em campo. Foram ajustadas as umidades iniciais das sementes para 15, 20 e 25%, e para cada umidade inicial, foram utilizadas quatro combinações de períodos de deterioração de 24 e 48 horas e temperaturas de deterioração de 40 e 45°C. Os resultados permitiram concluir que o tratamento com sementes com umidade inicial de 20%, por 48 horas sob temperatura de 45ºC, apresenta alta correlação com o teste de envelhecimento acelerado.

Application of the controlled deterioration test to evaluate wheat seed vigour

The objective of this study was to determine which combination of moisture content (m.c.), time and temperature in the Controlled Deterioration (CD) test, could be used to monitor seed vigour of wheat Triticum aestivum seed. The combination of 45°C and 18% m.c. for 72h provided good discrimination of post-CD germination and showed a high capacity to be considered as the best CD test for wheat seeds.

Adequação da metodologia do teste de deterioração controlada para sementes de brócolis (Brassica oleracea L. - var. itálica)

A eficiência dos testes de vigor na avaliação da qualidade de sementes, depende da sua padronização para as diferentes espécies. Neste contexto, os objetivos deste trabalho foram elaborar as curvas de absorção de água para determinar o período necessário ao ajuste do teor de água das sementes e aprimorar o teste de deterioração controlada para sementes de brócolis. Foram utilizadas sementes de três variedades: dois lotes de Piracicaba precoce, dois lotes de Flórida e quatro lotes de Ramoso. Os lotes foram caracterizados mediante a determinação do teor de água e germinação; o vigor foi determinado pelos testes de primeira contagem, comprimento de plântula, emergência e índice de velocidade de emergência. Foram determinadas as curvas de absorção de água por 84 horas. Para averiguar a eficiência do teste de deterioração controlada para sementes de brócolis, foi feito o ajuste do conteúdo de água das sementes para: 18, 20, 21, 23 e 24%, sendo estas expostas a 45ºC em banho-maria, por 24 horas. O delineamento utilizado foi o inteiramente casualizado. As médias foram comparadas pelo teste de Tukey a 5% de probabilidade. As curvas de absorção permitiram estimar os períodos de 15, 20, 22, 32 e 48 horas para elevação do teor de água a 18, 20, 21, 23 e 24% respectivamente. O teste de deterioração controlada, para sementes de brócolis, propiciou resultados promissores, tendo sido eficiente na separação de lotes, em todos os teores de água estudados, tanto quanto os testes de emergência de plântula e índice de velocidade de emergência.

Characterization of green seed, an enhancer of abi3-1 in Arabidopsis that affects seed longevity.

Seeds are usually stored in physiological conditions in which they gradually lose their viability and vigor depending on storage conditions, storage time, and genotype. Very little is known about the underlying genetics of seed storability and seed deterioration. We analyzed a mutant in Arabidopsis disturbed in seed storability. This mutant was isolated as a grs (green-seeded) mutant in an abi3-1 (abscisic acid 3) mutant background. Genetic and physiological characterization showed that the monogenic grs mutant was not visibly green seeded and mapped on chromosome 4. This enhancer mutation did not affect the ABA sensitivity of seed germination or seed dormancy but was found to affect seed storability and seedling vigor. Seed storability was assessed in a controlled deterioration test, in which the germination capacity of the mutant decreased with the duration of the treatment. The decrease in viability and vigor was confirmed by storing the seeds in two relative humidities (RHs) for a prolonged period. At 60% RH, the mutant lost germinability, but storage at 32% RH showed no decrease of germination although seed vigor decreased. The decrease in viability and vigor could be related to an increase in conductivity, suggesting membrane deterioration. This was not affected by light conditions during imbibition, expected to influence the generation of active oxygen species. During seed maturation, ABI3 regulates several processes: acquiring dormancy and long-term storability and loss of chlorophyll. Our results indicate that GRS is a common regulator in the latter two but not of dormancy/germination.

Aerated hydration treatment improves the response of Brassica juncea and Brassica campestris seeds to stress during germination

Seed lots of Brassica juncea and Brassica campestris that differed in quality were subjected to aerated hydration (AH) for up to 24 h at 20°C. In both species, the rate of germination, final germination (% normal seedlings) and germination after the controlled deterioration test increased after AH treatment in seeds that initially had reduced seed quality. The optimum timing of treatment was 12 h in both species. The germination of two seed lots of Brassica juncea was tested before and after 12 h AH at a range of water potentials (0 to -1.00 MPa) and salinities (0-331.8 mmolal NaCI). Both the final normal germination (%) and germination rate, as measured by mean germination time, decreased as water stress (decreased water potential) and salinity increased. However in all cases the normal germination (%) was markedly higher for AH treated seeds. Thus at -0.73 MPa, the normal germination of untreated seed of the two lots was 47 and 55% (mean of two repeat runs) compared with 90 and 91% following AH. Similarly, at 220.3 mmolal NaCI, the normal germination of the two lots increased to 78 and 85% after AH treatment, compared with 43 and 57% for untreated seeds. The effect of AH treatment on germination at a range of temperatures (8-37°C) was examined for seed lots of Brassica campestris. Germination increased at temperatures both above (33-37°C) and below (8-10, 13-14°C) the optimum for germination (22-23°C), thus extending the range of temperatures for successful germination. These results are discussed in relation to establishment under stressful conditions and the role of germination advancement and metabolic repair during AH treatment.

Accelerated aging and controlled deterioration for the determination of the physiological potential of onion seeds

International research on vegetable seed vigor is not at the same level attained for grain crops species. This study was conducted to identify reliable procedures for the accelerated aging and controlled deterioration tests to rank onion (Allium cepa L.) seed lots according to their physiological potential. Six seed lots of the cultivars Aurora and Petroline were evaluated in the laboratory for germination, first count, seedling vigor classification, traditional and saturated salt accelerated aging (41ºC / 48 and 72 h), controlled deterioration (24% of water / 45ºC / 24 h) and seedling emergence tests. Seed moisture content after the saturated salt accelerated aging test was lower and uniform, which is considered an important advantage in comparison to the traditional procedure. The saturated salt accelerated aging (41ºC / 48 and 72 h) and controlled deterioration (moisture content adjusted to 24% / 45ºC / 24 h) tests were the best procedures to assess the physiological potential of onion seeds, and are indicated for use in quality control programs.

Envelhecimento acelerado e deterioração controlada em sementes de tomate

Sementes de tomate apresentam alto valor comercial e, por esse motivo, merecem atenção especial quanto ao potencial fisiológico, principalmente devido às dificuldades para o armazenamento; para tanto, estudos dirigidos à determinação do vigor devem ser utilizados e intensificados. Este trabalho teve por objetivo estudar o envelhecimento acelerado e a deterioração controlada para avaliação do potencial fisiológico de sementes de tomate. Para tanto, cinco lotes de sementes, dos híbridos Debora Plus e Bruna, foram submetidos aos testes de germinação, emergência das plântulas em casa de vegetação, envelhecimento acelerado (empregando-se os períodos de 48 e 72 horas, a 38°C ou 41°C, com e sem o uso de solução saturada de NaCl) e deterioração controlada (sementes com graus de umidade de 19%, 21% e 24%, a 45°C, durante 24 e 48 horas). A combinação 72h / 41°C / com ou sem o uso da solução saturada de NaCl, no teste de envelhecimento acelerado, e a combinação 24% de água / 24h / 45°C, no teste de deterioração controlada, são eficientes para detectar diferenças de vigor entre os lotes de sementes de tomate.

Testes de envelhecimento acelerado e de deterioração controlada para avaliação do vigor de sementes de soja

A avaliação do de vigor é um importante componente no controle de qualidade da indústria de sementes. A pesquisa, conduzida com sementes de soja [Glycine max (L.) Merrill], não classificadas pelo tamanho, dos cultivares BR-37 e Embrapa 48, teve como objetivos estudar diferentes procedimentos para a distribuição das amostras na superfície da tela metálica das caixas plásticas, que constituem compartimentos individuais (câmaras internas), durante os períodos de exposição ao envelhecimento acelerado e de comparar os resultados com os do teste de deterioração controlada. No teste de envelhecimento acelerado foram utilizadas quatro subamostras para cada lote, previamente pesadas (42,5 g) ou distribuídas de modo a formar uma camada única de sementes na superfície da tela metálica. A manutenção da umidade relativa no interior de cada caixa plástica foi efetuada de duas maneiras: através da adição de 40 mL de água (100% U.R.) ou de 40 mL de solução saturada de cloreto de sódio (76% U.R.). As caixas plásticas permaneceram em B.O.D., a 41°C, durante 48 ou 72 horas. Em seguida, conduziu-se teste de germinação, a 25°C, com avaliação única aos quatro dias. O teste de deterioração controlada foi conduzido a 40°C durante 48 horas, após o ajuste do grau de umidade das sementes para 15,5%, seguido por germinação durante quatro dias. Os dois sistemas usados para a distribuição das amostras mantiveram a sensibilidade do teste de envelhecimento acelerado para identificar diferenças no vigor dos lotes avaliados, independentemente do uso de água ou de solução salina e do período de envelhecimento. O teste de deterioração controlada constitui alternativa tão consistente quanto o teste de envelhecimento acelerado para a avaliação do vigor de sementes de soja.

Genetic analysis of seed-soluble oligosaccharides in relation to seed storability of Arabidopsis.

Seed oligosaccharides (OSs) and especially raffinose series OSs (RSOs) are hypothesized to play an important role in the acquisition of desiccation tolerance and consequently in seed storability. In the present work we analyzed the seed-soluble OS (sucrose, raffinose, and stachyose) content of several Arabidopsis accessions and thus identified the genotype Cape Verde Islands having a very low RSO content. By performing quantitative trait loci (QTL) mapping in a recombinant inbred line population, we found one major QTL responsible for the practically monogenic segregation of seed stachyose content. This locus also affected the content of the two other OSs, sucrose, and raffinose. Two candidate genes encoding respectively for galactinol synthase and raffinose synthase were located within the genomic region around this major QTL. In addition, three smaller-effect QTL were identified, each one specifically affecting the content of an individual OS. Seed storability was analyzed in the same recombinant inbred line population by measuring viability (germination) under two different seed aging assays: after natural aging during 4 years of dry storage at room temperature and after artificial aging induced by a controlled deterioration test. Thus, four QTL responsible for the variation of this trait were mapped. Comparison of the QTL genetic positions showed that the genomic region containing the major OS locus did not significantly affect the seed storability. We concluded that in the studied material neither RSOs nor sucrose content had a specific effect on seed storability.

Application of the Normal Distribution for Testing the Potential of the Controlled Deterioration Test

The idea of vigor testing by the controlled deterioration test is usually illustrated by nonlinear courses of germination loss during the aging period. The aim of this analysis was to estimate the discrimination power of the controlled deterioration test by applying the assumptions about the nonlinear course made for establishing the Ellis and Roberts seed viability equation. The calculations showed that during the aging period, the differences in germination between seed lots increase according to the assumed normal distribution, while the sampling error of the germination test increases according to the binomial distribution. A gain of discrimination power was achieved when initial germination was higher than 50% and the duration of the aging period was optimized to achieve an average germination after the aging period of 50%. Experimental errors of the aging tests impair the discrimination power, whereas deviations from the assumptions made for the seed viability equation show the potential to improve the discrimination power.

Comparação entre métodos para avaliação da qualidade fisiológica de sementes de pimentão

The objective of the study was to compare the efficiency of different physiological quality evaluation methods in bell pepper (Capsicum annumm L.) seeds. Five seed lots were submitted to the following tests: standard germination, electrical conductivity, accelerated aging (with and without a saturated NaCl solution) and controlled deterioration. From the results obtained, it was concluded that electrical conductivity, accelerated aging (with a saturated NaCl solution) and controlled deterioration tests (seeds with 24% water) showed to be more efficient in detecting differences among physiological quality levels of the samples evaluated.

Chlorophyll fluorescence of Brassica oleracea seeds as a non-destructive marker for seed maturity and seed performance

AbstractA method is proposed for assessing the maturity and quality of seeds, based on measuring the amount of chlorophyll fluorescence (CF) signals of intact seeds. In general, the amount of chlorophyll is directly related to the degreening process and thus the maturity. Cabbage seeds (Brassica oleracea var. capitata) were separated into three subsamples based on the CF signals of the individual intact seeds. Seeds with the lowest amount of CF had the highest percentage of germination and normal seedlings. In a controlled deterioration test, the subsample with the lowest CF signal had slightly lower germination and normal seedling percentages than the non-treated seeds, whereas the seeds with the highest CF signals had much lower germination and normal seedling percentages. Advantages of the CF method for determining seed maturity and seed quality are its high sensitivity and fully non-destructive nature and the high speed at which the fluorescence is generated and measured.

Use of seed vigour tests to predict field emergence of lucerne(Medicago sativa)

Abstract The suitability of three vigour tests (electrical conductivity at different soaking periods, controlled deterioration at 20% seed moisture content, and germination index) for indicating field emergence of lucerne seed lots was studied using 10 seed lots with similar germination percentages. The seed emergences were assessed in glasshouse pot trails using field soil at 30, 50, 70, or 90% soil water‐holding capacity (WHC), and in field plots at two sowing dates. The seed lots differed significantly in seed vigour and in seedling emergence. The lower vigour seed lots had the lower seedling emergence rates both in the glasshouse and in the field. The standard germination test and the germination index did not show any significant correlation with seedling emergence in any glasshouse or field trial. Compared with the standard germination test, the electrical conductivity test was the most reliable for predicting seedling emergence in drier soils with significant correlation coefficients of r = ‐0.701 to ‐0.829 for soil held at 30% WHC and r = ‐0.696 to ‐0.850 in a field trial with two sowing dates. The controlled deterioration test also gave a significant correlation with seedling emergence under a moisture condition of 30% WHC. The results of electrical conductivity tests obtained from seed soaked for 4–20 h were significantly correlated with those from a 24‐h soaking (r = 0.952∗∗ to 0.999∗∗), which suggests that the soaking period for lucerne seed in the electrical conductivity test could be shortened.

Assessment of soybean seed vigour tests for eastern Australia

Vigour testing was undertaken on seed from 4 soybean [Glycine max (L.) Merr.] cultivars taken from field trials in eastern Australia. The seed from each cultivar exhibited moderate to good germination and a range in vigour. Vigour tests consisted of the controlled deterioration and modified versions of the accelerated aging test. Accelerated aging was carried out in 4 ways using 2 periods of incubation (76 and 96 h), with or without the seed protectant Thiram to control saprophytic fungi. Results were compared with seedling emergence from the same seed samples when planted in a controlled environment glasshouse. A combination of 2 day/night temperatures, cold (18/13�C), warm (33/28�C), and 3 soil moisture regimes, dry (-0.3 MPa), field capacity (-0.01 MPa) and saturated soil, produced a total of 6 different environments. Emergence was also recorded under a moderate daylnight temperature of 23/18�C in soil at field capacity. The standard germination test and modified accelerated aging test with a 72-h incubation period with Thiram were significantly (P<0.01) correlated with emergence from all 7 soil environments. A 96-h period of accelerated aging (with or without Thiram) tended to suppress germination and there was no correlation with emergence from most soil environments. The controlled deterioration test correlated with seedling emergence from most soil environments except for dry soil. The vigour test which gave the best indicator of performance under a range of different seedbed moisture and temperature conditions was the modified accelerated aging test using a 72-h incubation period with Thiram.