RESUMO: A germinação de sementes é um processo complexo controlado por muitos fatores, nos quais mecanismos físicos e bioquímicos estão envolvidos e a mobilização de reservas é decisiva para que esse processo ocorra. Embora a mobilização de reservas de sementes seja considerada um processo pós-germinativo, a mobilização das proteínas de reserva de sementes ocorre durante a germinação. Este estudo teve como objetivo quantificar as proteínas de sementes de genótipos de feijão durante os diferentes tempos de hidratação, a fim de compreender o processo de mobilização proteica e se há relação desse componente bioquímico com o vigor das sementes. Este estudo foi realizado utilizando sementes com diferentes níveis de vigor, genótipos com maior (13, 42, 55 e 81) e menor (07, 23, 44, 50, IPR-88-Uirapurú e Iapar 81) qualidade fisiológica. Os genótipos de alto vigor apresentaram maior eficiência na hidrólise e mobilização do componente proteico, pois apresentaram baixo teor de globulinas nos cotilédones na protrusão radicular em relação aos genótipos de baixo vigor (07, 23 e 50). A proteína inibidora da alfa-amilase, observada em todos os genótipos, está envolvida com o maior tempo necessário para a protrusão da radícula, de acordo com a diferença de intensidade da banda nos genótipos 07, 44 e Iapar 81.

ABSTRACT: Seed germination is a complex process controlled by many factors, in which physical and biochemical mechanisms are involved and the mobilization of reserves is crucial for this process to occur. Although, seed reserve mobilization is usually thought to be a post-germination process, seed reserve proteins mobilization occurs during germination. This study quantified seed proteins of bean genotypes during different hydration times, in order to understand the process of protein mobilization and whether there is relationship of this biochemical component with seed vigor. This study was conducted using seeds with different levels of vigor, genotypes with highest (13, 42, 55 and 81) and lowest (07, 23, 44, 50, IPR-88-Uirapurú and Iapar 81) physiological quality. High vigor genotypes showed greater efficiency in hydrolysis and mobilization of protein component, because they presented low globulins content in cotyledons at radicle protrusion in relation to low vigor genotypes (07, 23 and 50). The protein alpha-amylase inhibitor, observed in all genotypes, is involved with the longer time needed for radicle protrusion, according to the band intensity difference in genotypes 07, 44 and Iapar 81.

ABSTRACT. Seed reserve mobilization is considered a post-germination process; however, seed storage protein mobilization occurs during germination. Thus, the knowledge of seed protein composition is important to understand various processes during germination, and it be associated with seed vigor. Therefore, this study aimed to characterize landrace genotypes of common bean (Phaseolus vulgaris) through fractionation of seed storage proteins during germination and to verify the association between seed protein composition and seed vigor. Genotypes of the highest (55 and 81) and lowest (23 and 50) physiological quality were selected. Protein content analysis, profiling, and characterization were performed by combining different hydration times. Mass spectrometry involving in-gel digestion and MALDI-ToF analysis was employed for the qualitative identification of proteins. Glutelin extraction detected the enzyme lipoxygenase in genotypes 55 and 81 alone. In plants, this enzyme may be involved in diverse physiological processes, including growth and development, pest resistance, senescence, and response to wounding. In the process of germination, lipoxygenase removes reactive oxygen species during reserve mobilization; therefore, lipoxygenase may be a candidate biochemical marker for high-vigor genotypes.

ABSTRACT. Rock dusts in association with organic sources have been used in agriculture to improve soil chemical characteristics and food composition. In this context, this study aimed to evaluate the effect of the rock dusts siltstone, tephrite, and olivine melilitite pure or combined and associated or not with cattle manure on the chemical composition of soybean seeds of the cultivar BRS 232 grown on a Cambisol and Nitisol subjected to these treatments and conventional fertilization. For this, an experiment was carried out with pots in a greenhouse using a Cambisol and Nitisol to cultivate the soybean from January to May 2019 until seed production. The seeds were harvested, ground, and sieved through a 1 mm mesh sieve to determine the nutrient, phytate, and crude protein contents. The effects of the rock dusts on the chemical composition of seeds were directly related to the chemical characteristics of the evaluated soils. The tested rock dusts had a more pronounced response in the Cambisol (poorer soil) than in the Nitisol (more fertile). The contents and accumulation of nutrients in the seeds, as well as the total dry matter production in both soils subjected to the treatments with the rock dusts olivine melilitite and siltstone + olivine melilitite, pure and combined with manure, were similar and, in some cases, higher than the treatments subjected to conventional fertilization. The combination of manure and rock dusts provided an increase in the concentration of nutrients in both soils, resulting in their higher availability for plants and directly reflecting on the chemical composition of seeds.

Resumo: A composição das reservas está diretamente relacionada à manifestação do vigor da semente. No entanto, a manifestação do potencial fisiológico de linhagens e híbridos a partir da hidrólise de reservas não está elucidada. O objetivo neste trabalho foi verificar se há diferenças na hidrólise de compostos de reserva de sementes de linhagens ou híbridos de milho durante a germinação e verificar se eventuais alterações estão associadas ao vigor de sementes. A qualidade fisiológica foi avaliada pelo teste de germinação e de vigor por envelhecimento acelerado e teste de frio. A dinâmica de hidrólise foi determinada durante a embebição e germinação temporalmente em 0 h (sementes quiescentes), 12 h, 24 h, 30 h e 48 h por meio da determinação do conteúdo de ácido fítico e fósforo inorgânico, proteína total e solúvel, amido e açúcar solúvel. As linhagens apresentaram maior tempo para protrusão radicular e menor vigor em relação aos híbridos. As maiores taxas de hidrólise em linhagens foram observadas da fase I e ao final da fase II da germinação. Nos híbridos, as taxas se mantiveram, em média, constantes ao longo da germinação. As maiores diferenças na hidrólise dos compostos de reserva ocorre na fase II da germinação e diferenciam o metabolismo germinativo de híbridos e linhagens.

Abstract: Storage reserves composition is directly related to the manifestation of seed vigor. However, the physiological potential expression in inbred lines, as well as hybrids from the storage reserves hydrolysis, is not clear. Thus, the aim of this study was focused on verifying if there are differences in the hydrolysis of seed storage reserve of maize inbred lines or hybrids during germination, and also checking if the changes in hydrolysis are associated with seed vigor. The seeds of inbred lines and hybrids were submitted to germination test, vigor by accelerated aging and cold tolerance. Biochemical profiling (total protein content, soluble proteins, phytate, inorganic phosphorus, starch, and soluble sugars), was temporally determined at 0 h (quiescent seeds), 12 h, 24 h, 30 h, and 48 h after imbibition. The seeds of inbred lines showed a longer time for root protrusion and less vigor when compared to hybrids. The highest hydrolysis rates in inbred lines were observed in phase I and at the end of phase II of germination. In hybrids, the rates remained, on average, constant throughout germination. The greatest differences in the hydrolysis of reserve compounds occur in phase II of germination and differentiate the germination metabolism of hybrids and inbred lines.

Resumo: A amostragem representativa do lote é importante na análise da qualidade das sementes. O objetivo neste trabalho foi verificar se a amostragem durante o fluxo de beneficiamento e a amostragem com o uso de caladores após o acondicionamento das sementes pode interferir na análise da qualidade fisiológica e sanitária de lotes de sementes de soja. O trabalho foi realizado com seis e doze lotes de sementes de soja produzidas nas safras 2017/2018 e 2018/2019, respectivamente. Para a amostragem dos lotes utilizaram-se dois métodos conforme descrito pelas Regras de Análises de Sementes: a) amostragem durante o fluxo de beneficiamento; b) amostragem dos lotes de sementes armazenados em “bags” com o uso de calador. Avaliou-se a qualidade das sementes pelo percentual de germinação, vigor por envelhecimento acelerado, tetrazólio e pela determinação da sanidade das sementes pelo blotter test. A amostragem durante o fluxo do beneficiamento e nos “bags” após o armazenamento, diferiu na expressão do vigor e da qualidade sanitária das sementes. A homogeneidade do lote é preponderante para verificar a diferença dos métodos de amostragem. A amostragem no fluxo do beneficiamento é mais representativa e pode ser indicada para o teste de germinação.

Abstract: Representative seed lot sampling is important in analyzing seed quality. This study aimed to determine whether sampling during processing and after packaging using samplers interferes in analyzing the physiological quality and health of soybean seed lots. The study was conducted with six and twelve soybean seed lots produced in the 2017/2018 and 2018/2019 growing seasons, respectively. Two sampling methods were used, according to the Rules for Seed Testing: a) sampling during processing; b) sampling of seed lots stored in bags using a sampler. Seed quality was assessed by germination percentage, accelerated aging, and tetrazolium tests to determine vigor, and seed health using the blotter test. Sampling during processing and after storage in bags differ in the expression of seed vigor and health. Seed lot homogeneity is essential to determine the difference between sampling methods. Sampling in the processing flow is more representative and may be indicated for the germination test.

RESUMO As principais causas da redução na porcentagem de emergência a campo é a ocorrência de estresses abióticos, especialmente o estresse hídrico e salino. Diversos estudos associam a maior concentração de prolina com a tolerância de cultivares a esses estresses. Entretanto, é necessário determinar como o genótipo e o vigor atuam durante a formação de plântulas, e como a concentração de prolina interage com esses fatores. O objetivo deste trabalho foi avaliar a relação da prolina com o genótipo e o vigor de sementes durante o estabelecimento das plântulas em condições de estresse hídrico e salino. Foram utilizados os genótipos BAF07, BAF13, BAF23, BAF42, BAF44, BAF55 e BAF112, as quais foram submetidas a germinação em estresse hídrico e salino. Aos 10 dias após a semeadura foram avaliados o comprimento, massa seca das plântulas e capacidade de mobilização de reservas, assim como o teor de prolina livre das plântulas. O uso de sementes de alto vigor e genótipos tolerantes influenciam na superação dos estresses hídrico e salino e devem ser utilizados como estratégia durante a semeadura e, a maior concentração prolina não apresentou associação com o maior vigor do lote de sementes ou aos genótipos tolerantes.

ABSTRACT Abiotic stresses, especially water and saline stress, are the main causes of reduced field emergence percentage. Several studies have associated the higher concentration of proline with the tolerance of cultivars to these stresses. However, one needs to determine how genotype and seed vigor act during seedling formation in the presence of stresses and how proline concentration interacts with these factors. The objective of this work was to evaluate the relationships of proline with genotype and seed vigor in seedling formation under drought and saline stress. The genotypes BAF07, BAF13, BAF23, BAF42, BAF44, BAF55 and BAF112 were used. They were subjected to germination tests under water and saline stress. At ten days after sowing, the following parameters were assessed: length, seedling dry mass and capacity to mobilize reserves, as well as the free proline content of the seedlings. Seed vigor and tolerant genotypes may help overcome water and saline stresses, and they should be used as a strategy during sowing. Also, higher proline concentrations are not associated with higher either vigor of the seed lot or tolerant genotypes.

Resumo: A deterioração de sementes é um processo contínuo e irreversível, atuando em estruturas e moléculas constituintes celulares e ocasionando a perda da qualidade fisiológica das sementes. Objetivou-se com este trabalho avaliar as alterações causadas pela deterioração artificial de sementes de trigo na germinação e desempenho de plântulas. Foram utilizadas sementes da cultivar TBIO Toruk, submetidas a diferentes tempos de envelhecimento artificial (2, 3, 4, 5, 6 e 7 dias). Após a obtenção dos lotes envelhecidos, juntamente com o lote original, foram conduzidos em laboratório os testes de germinação e desempenho de plântulas (comprimento total e massa seca total de plântulas e massa seca remanescente em endosperma). Foram quantificados o marcador de estresse oxidativo malondialdeído, a atividade da enzima alfa-amilase e a condutividade elétrica. O exsudato resultante da avaliação do teste de condutividade elétrica foi separado para a quantificação de açúcares solúveis totais, proteínas solúveis e fósforo. O processo de deterioração resultou em aumento da peroxidação de lipídeos e decréscimo da atividade inicial de alfa-amilase. Durante a germinação, os lotes mais deteriorados apresentaram maior perda de solutos e menor capacidade de síntese de alfa-amilase. Os lotes com maior nível de deterioração apresentaram decréscimo na viabilidade e formaram plântulas de menor desempenho.

Abstract: Seed deterioration is a continuous irreversible process that affects cell structures and molecules and compromises the physiological quality of seeds. This study aimed to assess the effect of artificial wheat seed deterioration on germination and seedling performance. The TBIO Toruk wheat cultivar was used, with seeds submitted to different artificial aging times (2, 3, 4, 5, 6 and 7 days). The original and aged seed lots were submitted to laboratory germination and seedling performance tests (seedling length, seedling dry weight and endosperm dry weight). Alpha-amylase activity, electrical conductivity and the oxidative stress marker malondialdehyde were quantified. The exudate resulting from the electrical conductivity test was separated to quantify total soluble sugars, soluble proteins and phosphorus. The deterioration process increased lipid peroxidation and decreased initial alpha-amylase activity. During germination, the most deteriorated lots exhibited greater solute loss and lower alpha-amylase synthesis capacity. The lots with the greatest deterioration showed reduced viability and produced worse-performing seedlings.

RESUMO Acredita-se que o uso de sementes de alto vigor aliado ao ajuste da densidade na semeadura pode garantir altas produtividades, porém esta prática levanta dúvidas quanto ao seu efeito no cultivo do arroz pela sua capacidade de perfilhamento. Desta forma, o objetivo do trabalho foi determinar a influência do ajuste da densidade de semeadura pelo vigor sobre o estabelecimento inicial de plântulas a campo. Realizou-se uma caracterização fisiológica utilizando teste de germinação, vigor pelo envelhecimento acelerado, condutividade elétrica, primeira contagem, comprimento de parte aérea, raiz e plântula e massa seca nas safras 2019/2020 e 2020/2021 sob delineamento inteiramente casualizado com quatro repetições. Em seguida, foi selecionado lotes de sementes, onde uma fração deles foi submetida a redução artificial do vigor. Posteriormente foi realizada a semeadura nas principais regiões produtoras de Santa Catarina, sob delineamento de blocos ao acaso com quatro repetições, considerando os tratamentos sem ajuste da densidade, com ajuste pela germinação e com ajuste pelo vigor no envelhecimento acelerado. Aos vinte e um dias após a semeadura foi avaliado as plântulas emergidas por área. Observou-se interação entre os fatores ajuste da densidade e qualidade da semente, já que mesmo com o ajuste da densidade pelo vigor, o lote de menor qualidade apresentou número de plântulas emergidas inferior, não equivalendo ao desempenho do lote com qualidade superior. Desta forma, conclui-se que o ajuste da densidade de semeadura pelo vigor aliado ao uso de sementes com alto vigor proporciona um incremento significativo na emergência de plantas no estabelecimento inicial a campo.

ABSTRACT The use of high-vigor seeds combined with seeding density adjustment at sowing is speculated to ensure high yields. However, certain doubts regarding the effect of this combined approach on rice cultivation remain owing to the tillering capacity. In this context, the present study aimed to determine the effects of seeding density adjustment according to vigor on the initial establishment of seedlings in the field. A physiological characterization was conducted using the germination test, vigor by accelerated aging, electrical conductivity, first count, shoot length, root length, total seedling length, and dry mass in the 2019/2020 and 2020/2021 growing seasons. The evaluations were conducted using a completely randomized design with four replications. Subsequently, the seed lots were selected, from which a fraction of seeds were submitted to artificial vigor reduction. Afterward, these seeds were sown in the main producing regions of the state of Santa Catarina, under a randomized block design with four replications. Three treatment groups were formed: one without density adjustment, one with adjustment by germination, and one with adjustment by vigor in accelerated aging. Twenty-one days after sowing, the number of emerged seedlings per unit area was determined. An interaction between the factors of adjustment for density and seed quality was observed. This was evidenced in the fact that even with the adjustment of density by vigor, the seed lot with lower quality presented the emergence of a lower number of seedlings, and the performance of these seeds was not equivalent to that observed in the lot with superior quality. Accordingly, it was concluded that the seeding density adjustment by vigor combined with the use of seeds with high-vigor is a suitable strategy for achieving a significant increase in plant emergence during the initial establishment in the field.

RESUMO O armazenamento é um conjunto de técnicas adotadas durante o período de entressafra visando o condicionamento das sementes para a manutenção da sua qualidade para a próxima safra. O estudo do efeito do armazenamento é importante para se conhecer a performance da dormência sob diferentes ambientes e a influência da temperatura e umidade relativa do ar no armazenamento sobre as sementes de arroz. Portanto, objetivou-se avaliar a qualidade fisiológica das sementes no armazenamento, para compreender se as condições ambientais influenciam na superação da dormência e na qualidade fisiológica das sementes de arroz. O experimento foi conduzido em delineamento inteiramente casualizado em esquema fatorial: armazenamento x tempos de avaliação x cultivar. Foram submetidas ao armazenamento em câmara seca (10 (C e 50% UR) e convencional (sem controle de temperatura e umidade relativa do ar), sementes de cultivares de arroz provenientes da Região do Alto Vale do Itajaí, SC, safras 2016/17 e 2017/18. Realizou-se os testes de germinação, vigor após o envelhecimento acelerado e tetrazólio durante o armazenamento. A dormência foi afetada pelas condições de armazenamento. E afetou a germinação e o vigor das sementes. Conclui-se que as condições de temperatura e umidade no armazenamento afetam a superação da dormência de sementes de arroz. A câmara seca (10 ºC e 50% UR) favorece a superação da dormência e a manutenção da qualidade fisiológica das sementes dos cultivares de arroz Epagri 109, SCS121 CL, SCS122 Miura e Primoriso CL.

ABSTRACT Storage is a set of techniques adopted during the off-season, aiming at conditioning the seeds to maintain their quality for the next harvest. The study of effect by storage is important to know the performance of dormancy under different environments and the influence of temperature and relative humidity in the storage on rice seeds. Therefore, the objective was to evaluate the physiological quality of seeds in storage, to understand whether environmental conditions influence in overcoming dormancy and the physiological quality of rice seeds. The experiment was conducted in a completely randomized design in a factorial scheme: storage x evaluation times x cultivar. Seeds of rice cultivars from the Alto Vale do Itajaí, SC, from the 2016/17 and 2017/18 seasons were submitted to storage in a dry chamber (10 ºC and 50% RH) and conventional (without temperature and relative humidity control). Germination, vigor by accelerated aging and tetrazolium tests during storage were performed. Dormancy was affected by storage conditions. And it affected the germination and vigor of the seeds. It is concluded that the temperature and humidity conditions in the storage affect the overcoming of the dormancy of rice seeds. The dry chamber (10 ºC and 50% RH) favors the overcoming of dormancy and the maintenance of the physiological quality of the seeds of the rice cultivars Epagri 109, SCS121 CL, SCS122 Miura and Primoriso CL.

RESUMO: O conhecimento do efeito do inóculo na semente é importante para conhecimento do nível de tolerância do patógeno pela semente. Objetivo deste trabalho foi avaliar o efeito da incidência do fungo Microdochium allbescens sobre a qualidade fisiológica das sementes de diferentes cultivares de arroz irrigado. O estudo foi realizado nos laboratórios de análises de sementes (LAS), fitopatologia e na casa de vegetação, localizados no Centro de Ciências Agroveterinárias da Universidade do Estado de Santa Catarina, Lages, SC. Utilizaram-se sementes de seis cultivares de arroz irrigado produzidas na Região do Alto Vale do Itajaí na safra 2016/17. Os lotes foram submetidos ao teste de sanidade de sementes, identificando-se quatro lotes por cultivar com incidência natural de M. albescens, sendo designados dois lotes de cada cultivar com incidência superior a 40% e dois lotes igual ou inferior a 40%, totalizando 24 lotes de sementes. Foram realizadas as seguintes avaliações nos lotes: germinação, teste de envelhecimento acelerado, emergência em casa de vegetação aos 14 dias, índice de velocidade de emergência (IVE), velocidade de emergência (VE), comprimento de parte aérea, comprimento de raiz e massa seca. Houve interação significativa entre cultivar e nível de incidência apenas nas variáveis germinação, vigor e comprimento de raiz. A massa fresca, comprimento da parte aérea e IVE não foram afetados, independente do cultivar e incidência do fungo na semente. Os cultivares de arroz irrigado SCS118 Marquês e SCSBRS Tio Taka são suscetíveis à alta incidência (> 40%) do fungo M. albescens.

ABSTRACT: Knowledge of the effect of the seedborne inoculum is important for knowing the level of tolerance of the pathogen by the seed. This research evaluated the effect of the incidence of the fungus Microdochium albescens on the physiological quality of the seeds of different cultivars of irrigated rice. The study was carried out in the seed testing laboratory (STL), phytopathology laboratory and in greenhouse, located at the Center of Agroveterinary Sciences of the Santa Catarina State University, Lages, SC, Brazil. Seeds from six irrigated rice cultivars produced in the Alto Vale do Itajaí Region in the 2016/17 harvest, were used. The lots were submitted to the seed health test, identifying four lots per cultivar with a natural incidence of M. albescens, with two lots of each cultivar with an incidence greater than 40% and two lots equal or less than 40%, totaling 24 seed lots. The following evaluations were carried out on the lots: germination, accelerated aging test, emergence in a greenhouse at 14 days, emergence speed index (ESI), emergence speed (ES), shoot length, root length and fresh and dry mass. There was a significant interaction between cultivar and level of incidence only in the variables germination, vigor and root length. Fresh mass, shoot length and ESI were not affected, regardless of cultivar and incidence of fungus in the seed. The irrigated rice cultivars SCS118 Marquês and SCSBRS Tio Taka are susceptible to a high incidence (> 40%) of the fungus M. allbescens.

ABSTRACT Producing high-quality seeds for agroecological agriculture is needed because the plants will be exposed to a diversity of environments and management practices. Sowing times and population densities can influence the quality of seeds produced by landraces. Further, seeds for agroecological cultivation must not be contaminated by transgenes. In this context, it is necessary to know the agronomic performance of landraces outside of the recommended growing period to avoid gene flow with transgenic cultivars. Thus, the objective of this work was to determine the germination rate, vigor and sanitary quality of seeds of maize genotypes cultivated in an agroecological system at different sowing times and densities. A split-split-plot design was used in the 2016/2017 and 2017/2018 growing seasons. The physiological quality evaluation was based on germination and vigor tests, and the sanitary quality was obtained by visually examining the seeds. The results showed a significant simple effect of genotype, sowing time and density, as well as double and triple interactions among factors for all evaluated traits. The most suitable time for sowing the corn landraces evaluated in an agroecological system in western Santa Catarina is September, when the seeds exhibited the highest percentage of germination and vigor and there was a lower incidence of pathogens. At this time, a density of 55,000 plants·ha–1 had the best result for germination. Late sowing was tested to avoid gene flow from transgenic varieties that usually are sown in September, but the results indicated penalties, such as a decrease in seed yield and quality.

RESUMO A eficiência da mobilização de reservas em sementes pode ser afetada pelas características do genótipo e sua qualidade fisiológica inicial, sendo determinantes na escolha de cultivares que apresentem melhor desempenho fisiológico a campo. O estudo teve como objetivo avaliar a mobilização de reservas em diferentes cultivares de feijão com contraste no vigor, buscando determinar como esse processo se diferencia entre esses lotes e cultivares. Foram utilizadas seis cultivares produzidas nas safras 2017/2018 e 2018/2019 em Lages, Santa Catarina, Brasil. A qualidade fisiológica das cultivares foi definida pelo teste de germinação, teste de envelhecimento acelerado, comprimento de plântulas e pelo índice de vigor, sendo determinados dois grupos de vigor (maior e menor vigor). A mobilização de reservas foi avaliada pela massa seca de sementes e de plântulas, utilização de reservas da semente, taxa de utilização de reservas da semente, taxa de mobilização de reservas para a plântula e pela eficiência de uso das reservas da semente. As cultivares caracterizadas como de maior vigor apresentaram maior taxa de utilização de reservas, taxa de mobilização de reservas para a plântula e maior eficiência de uso de reservas, favorecendo a formação de plântulas vigorosas. A avaliação da mobilização de reserva é uma alternativa para o uso em programa de controle de qualidade e seleção de cultivares com maior vigor.

ABSTRACT The efficiency of seed reserve mobilization (SRM) can be affected by genotype characteristics and seed initial physiological quality, which are determinant for the choice of cultivars that present plants with high physiological performances. The objective of this study was to evaluate the SRM in different common bean cultivars with different vigor and determine the differences in this process between seed lots and cultivars. Six common bean cultivars were grown in the 2017-2018 and 2018-2019 crop seasons in Lages, Santa Catarina, Brazil. The physiological quality of the cultivars was defined by germination test, accelerated aging test, seedling length, and vigor index, establishing two vigor groups (high vigor and low vigor). SRM was evaluated based on seed and seedling dry weights, use of seed reserves, use rate of seed reserves, SRM rate to the seedling, and use efficiency of seed reserves. The high-vigor cultivars presented higher use rates of seed reserves, SRM rate to the seedling, and use efficiency of seed reserves, favoring the development of vigorous seedlings. The evaluation of SRM is an alternative to improve control of internal seed quality and selection of high-vigor common bean cultivars.

ABSTRACT This study aimed to evaluate changes in germination and in the amount of carbohydrates, starch, proteins, and lipids of A. angustifolia seeds at different stages of development. Seeds were collected in the Cotyledonary Stage and Stages I, II, III and IV. Germination, moisture content, dry matter amount, and levels of carbohydrates, starch, proteins, lipids and fatty acids were determined. Both embryo and megagametophyte contained the starch as the large reserve content, while proteins and mainly lipids represented only a small proportion. During seed development, the highest values for germination, starch and soluble carbohydrate content were observed at stage IV. Although, soluble protein content had decreased from Cotyledonary Stage to Stage III, an increase at Stage IV was observed in the embryo. No difference was observed in lipid content. Linoleic acid was more abundant in fatty acids. Thus, A. angustifolia embryo showed an increase soluble protein content, an accumulation of dry matter and soluble carbohydrate content at Stage IV. It seems that these compounds collaborate to faster and higher germination.

ABSTRACT. The objective of this work was to evaluate the alterations of antioxidant enzyme reserves and antioxidant enzymes during germination under water deficit in maize hybrids and to associate with seed vigor, determining the mechanisms related to tolerance for this stress. Two three-way maize hybrids were characterized by their vigor at different levels of water deficit induced by polyethylene glycol 6000. Next, the seeds were hydrated at different osmotic potentials (0.0, -0.3, and -0.9 MPa) and removed at different times to assess the levels of the total soluble protein, total soluble sugars, proline, starch, and antioxidant enzymes, such as superoxide dismutase, catalase and ascorbate peroxidase. The analysis of variance, Tukey test at 5% and principal component analysis (PCA) were used. The vigorous hybrid (HT1) was more efficient than the low vigor hybrid seeds (HT2) in mobilizing the total soluble protein during the initial stages of germination and the total soluble sugars before and after root protrusion under water deficit in addition to increasing the catalase activity at the different osmotic potentials that were assessed.

RESUMO: O fungo Microdochium albescens é um dos principais patógenos associados às sementes de arroz irrigado no sul do Brasil. O objetivo do presente estudo foi quantificar a transmissão de M. albescens de sementes naturalmente infectadas para a coroa, coleóptilo e primeira folha verdadeira das plântulas de seis cultivares semeadas em sistema de cultivo pré-germinado de arroz irrigado. A semeadura foi realizada em substrato saturado com água, utilizando quatro lotes de sementes não tratadas para cada uma das seis cultivares. Aos 14 dias após a semeadura, a coroa, o coleóptilo e a primeira folha verdadeira das plântulas foram cuidadosamente dissecados, desinfestados e plaqueados em meio de cultura batata-sacarose-ágar. M. abescens foi transmitido de forma assintomática para coroa, coleóptilo e primeira folha verdadeira, nas taxas de 39,3%, 25,8% e 5,4%, respectivamente (estes valores representam a incidência média das seis cultivares). Este é o primeiro relato de M. albescens transmitido de sementes infectadas para plântulas de arroz irrigado em sistema de semente pré-germinada.

ABSTRACT: The fungus Microdochium albescens is one of the main pathogens associated with irrigated rice seeds in southern Brazil. The objective of the present study was to quantify the transmission of M. albescens from naturally infected seeds to the crown, coleoptile, and first true leaf of the seedlings of six cultivars growing in pre-germinated cultivation system of irrigated rice. Seeding was carried out on a water-saturated substrate, using four untreated seed lots for each of the six cultivars. At 14 days after sowing, the crown, coleoptile, and first true leaf of the seedlings were carefully highlighted, and the samples were disinfected and plated onto potato-sucrose-agar culture medium. M. albescens was transmitted asymptomatically to crown, coleoptile, and first true leaf, at rates of 39.3%, 25.8%, and 5.4%, respectively (these values represent the average incidence of the six cultivars). This is the first report that proves that M. albescens is transmitted from infected seeds to irrigated rice seedlings in a pre-germinated seed system.