Tratamentos pré-germinativos em sementes de cajá (Spondias mombin L.)

The germination of Spondias mombin seeds is slow and irregular – it takes between 6 and 24 months for the process to complete.  This causes the plantlets producer serious difficulties since the plantlets are more expensive to produce and frequently are of different heights.  The objective of this project was to establish techniques and strategies of Spondias mombin seed selection to promote and speed up germination. Having that in mind, two experiments were carried out. In the first, seeds (which are of the nucular type) of two colors (beige and brown) and four classes of size (small, medium-small, medium-large, and large) had their length, width, and weight determined. In the second experiment, the color (beige and brown) classified seeds were submitted or not to a fungicide treatment and to mechanical scarification of the endocarp (base, apex, lateral, and no scarification). The experiments were distributed according to a completely random design with four 20 seeds replications in the following factorial arrangements: 4x2 (size x color) and 4x2x2 (scarification x color x fungicide). Seedling emergence in sand, first count of germination, and mean time for germination were weekly determined up to 730 days; these evaluations were based on the determination of normal seedlings counting.  Choosing brown and medium-large seeds is an efficient strategy to accelerate seedling emergence. Treating the seeds with fungicide was harmful to the germination process.  The lateral scarification of brown seeds permitted a reduction in the period necessary for the completion of germination from 489 to 336 days.As sementes de cajá apresentam germinação lenta e desuniforme, pois o processo normalmente tem duração de seis meses e dois anos. Tal característica constitui-se em entrave para os viveiristas, pois onera os custos de produção e resulta em mudas com tamanhos diversos. O objetivo deste trabalho foi estabelecer técnicas e estratégias de seleção de sementes de cajá (Spondias mombin L.) que promovam ou acelerem a germinação. Para tanto, foram realizados dois experimentos. No primeiro, foram avaliadas sementes (nuculânios) de duas cores (bege e marrom) e quatro classes de tamanho (pequena, média-pequena, média-grande e grande) caracterizadas por meio do comprimento, largura e massa. No segundo experimento, as sementes classificadas quanto à cor (bege e marrom) foram submetidas ou não à aplicação de fungicida e à escarificação mecânica do endocarpo (base, ápice, lateral e sem escarificação mecânica). Os experimentos foram instalados em delineamento inteiramente casualizado com quatro repetições de 20 sementes, nos seguintes arranjos fatoriais: 4 x 2 (tamanho x cor) e 4 x 2 x 2 (escarificação x cor x fungicida). Avaliou-se a emergência de plântulas em areia, primeira contagem e o tempo médio da emergência. Em ambos os estudos, a emergência foi avaliada semanalmente, até os 730 dias. Concluiu-se que a seleção de sementes marrons e média-grandes (31 x 18 cm e 2,16 g) constituiu-se em uma estratégia eficiente para aumentar e acelerar a emergência de plântulas. O tratamento das sementes com fungicida (metalaxil-M+fludioxonil) foi prejudicial ao processo germinativo. A utilização de sementes marrons e escarificadas na lateral possibilitou a aceleração da germinação (tempo médio de 489 para 336 dias)

Production fields and physiological quality of Panicum maximum jacq. cv. mombasa seeds

The physiological quality of seeds is influenced by the climatic factors of production fields. The identification of the best conditions of P. maximum cv. Mombasa production fields allows the improvement of the seed sector. The aim of this work was to identify which climatic conditions of production fields can affect the physiological quality of P. maximum cv. Mombasa seeds. Nineteen plots from states of São Paulo (six from municipalities of Auriflama and three from Guzolândia) and Goiás (eight from Quirinópolis and two from Serranópolis), were collected by soil sweeping. The following parameters were evaluated: water content, germination rate, first germination count and germination rate index, seedling emergence in sand and field. Completely randomized design was used for all variables, with the exception of seedling emergence in field, since this variable required block design. Means were compared by the Scott-Knott test, at 5% probability. For the identification of the influence of climatic conditions on the physiological quality of seeds, multivariate statistical analysis was applied through Group and Principal Component Analysis. Production fields of Panicum maximum cv. Mombasa seeds presenting maximum temperatures above 32 ºC at flowering and natural fall stages produce seeds of low physiological quality. Production fields in which precipitation and high temperatures occur during natural fall and harvest of P. maximum cv. Mombasa seeds are not favorable to the production of seeds with high physiological quality

Seed conditioning process in the sanitary quality of marandu grass seeds

The purpose of seed conditioning process is to separate seeds and their associated structures into different fractions and retain only good and healthy seeds. Thus, the aim of this study was to evaluate the effects the stages of seed conditioning have on the sanitary quality of marandu grass seeds. The seeds were sampled before and during the seed conditioning process, i.e., after exiting the air-screen cleaner and sieves (seeds discharged from the top, middle and bottom sieves), the first gravity separator (seeds drifting around the table, upper and intermediate discharge) and second gravity separator (upper, intermediate and lower discharge). The sanitary analysis was performed using the filter paper method with and without surface disinfestation of the seeds, which were incubated at 20±2°C, with a photoperiod of 12 hours for seven days. The experiment was conducted in a completely randomized design, in a 2x6 factorial scheme (surface disinfestation x stages of the seed conditioning process) and ten replications. The data was submitted to analysis of variance, using the F test and, when significant, the means of the treatments were compared using the Tukey test at 5% probability. It was concluded that it is not possible to improve the sanitary quality of marandú grass seeds through the seed conditioning process

Dormancy overcoming in seeds of cajá-manga (Spondias dulcis)

The propagation of ‘cajá-manga’ (Spondias dulcis) is usually performed by seeds. The presence of dormancy is an obstacle for seedling production and the commercial use of its main product, the fruit. This research aimed to evaluate the use of phytoregulators associated with the scarification of the distal region of the embryo in dormancy overcoming and in the standardization of germination of ‘cajá-manga’ seedlings. Endocarps extracted from fruits of six matrices were subjected to the following treatments: control (T1), mechanic scarification in the distal region of the embryonic axis (T2); all following treatments involved scarification and imbibition in a solution of: water for 6h (T3); GA3 (750 mgL-1) for 6h (T4); GA3 (350 mg L-1) for 12h (T5); Cytokinin (750 mg L-1) for 6h (T6); Cytokinin (350 mg L-1) for 12h (T7); GA3 and Cytokinin (750 mg L-1) for 6h (T8); and GA3 and Cytokinin sowing 25 endocarps in expanded polystyrene trays using a washed sand substrate. The following variables were evaluated: emergence, first emergence count, emergence speed index, mean emergence time, shoot and root length of seedlings, and relative emergence frequency. The experimental design was in randomized blocks, with 9 treatments and four replications consisting of 25 endocarps each. The data obtained were subjected to the F Test at a 1% level of probability, as well as to the Scott-Knott method. The use of mechanic scarification in the opposite region of the embryonic axis, followed by the imbibition in a solution of gibberellin + cytokinin at the concentration of 350 mgL-1 for 12 hours is promising for dormancy overcoming in seeds of Spondias dulcis.The propagation of ‘cajá-manga’ (Spondias dulcis) is usually performed by seeds. The presence of dormancy is an obstacle for seedling production and the commercial use of its main product, the fruit. This research aimed to evaluate the use of phytoregulators associated with the scarification of the distal region of the embryo in dormancy overcoming and in the standardization of germination of ‘cajá-manga’ seedlings. Endocarps extracted from fruits of six matrices were subjected to the following treatments: control (T1), mechanic scarification in the distal region of the embryonic axis (T2); all following treatments involved scarification and imbibition in a solution of: water for 6h (T3); GA3 (750 mgL-1) for 6h (T4); GA3 (350 mg L-1) for 12h (T5); Cytokinin (750 mg L-1) for 6h (T6); Cytokinin (350 mg L-1) for 12h (T7); GA3 and Cytokinin (750 mg L-1) for 6h (T8); and GA3 and Cytokinin sowing 25 endocarps in expanded polystyrene trays using a washed sand substrate. The following variables were evaluated: emergence, first emergence count, emergence speed index, mean emergence time, shoot and root length of seedlings, and relative emergence frequency. The experimental design was in randomized blocks, with 9 treatments and four replications consisting of 25 endocarps each. The data obtained were subjected to the F Test at a 1% level of probability, as well as to the Scott-Knott method. The use of mechanic scarification in the opposite region of the embryonic axis, followed by the imbibition in a solution of gibberellin + cytokinin at the concentration of 350 mgL-1 for 12 hours is promising for dormancy overcoming in seeds of Spondias dulcis

Water stress on the physiology of germination and seedling morphoanatomy Myracrodruon urundeuva Fr. All. (Anacardiaceae)

The Caatinga Biome, even with the approach of recent years, is a region lacking of information that enables the understanding of how plants survive on stress conditions. Species that make up this biome, Myracrodruon urundeuva Fr. All. stand out for timber and medicinal properties, suffering for decades, intense and predatory exploitation, leading to compose the official IBAMA list of endangered flora. The aim of this work was to select individuals of M. urundeuva through viability and vigor tests and to evaluate the effect of water stress on seedling emergence of normal and morphoanatomy. For such individuals mastic were selected in three areas of Paraiba State, a municipality of the ray tracing and two in Boa Vista, in which diasporas were collected and sent to the Laboratory of Seed Analysis (LAS) UFPB, Areia-PB. Initially it has proceeded to determine the water content (TA) and the following assessments: Germination test (GT), emergency testing (ET), first count of germination and emergence (FCG and FCE), germination speed index and emergency speed index (GSI and ESI), length and dry weight of seedlings. The methodology for implementing saline accelerated aging was also determined. Thereafter individual diasporas (matrix) more vigorous of the three areas were subjected to water stress under conditions of retention capacity of the soil levels: 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 and 60%. In this step we assessed the TA, TE, PCE, IVE, length and dry weight of roots and shoots of seedlings. To evaluate the morphoanatomy, diasporas mastic were subjected to the same continuous water conditions, described above, and a second temporary water condition. For this, they were initially sown in the soil retention capacity of 60%, then to simulate drought with stopping of watering until obtaining the capacities of 10, 15, 20, 25 and 30% retention. After subjected to continuous and temporary water conditions, morphoanatomical characteristics evaluated were: number of leaves, length and width of the primary, length, width and thickness of the central leaflet leaf; length, width and thickness of the cotyledon; number of stomata in the leaf and cotyledon length and diameter of the stem and root. In the initial evaluation of the seeds was observed that individuals of M. urundeuva germination and vigor have differentiated between the collection areas, as well as within the same area, demonstrating the adaptive plasticity of the species. The accelerated aging test in saline temperature of 41 °C during 24 hours is recommended due to the reduction of fungi, the eleventh individual, the stronger this test. When the eleventh individual diasporas were subjected to water stress, it was found that they have some degree of demand relative to water in the early periods of development. The structural and physiological assessments seedlings have adaptive characteristics for perpetuation over time and space in a natural environment. As for water regimes applied in the evaluation of morphoanatomical characteristics, treatments affected seedling development of mastic, and capabilities between 50 and 60% retention of the best treatments for the production of normal seedlings, for most variables.O Bioma Caatinga, mesmo com o enfoque dos últimos anos, é uma região carente em informações que permita o entendimento de como as plantas sobrevivem a condições de estresse. Das espécies que compõem esse Bioma, Myracrodruon urundeuva Fr. All. destacase pelas propriedades medicinais e madeireiras, sofrendo, ao longo de décadas, intensa e predatória exploração, levando-a compor a lista oficial do IBAMA da flora brasileira ameaçada de extinção. Assim, o objetivo deste trabalho foi selecionar indivíduos de M. urundeuva através de testes de viabilidade e vigor, assim como avaliar o efeito do estresse hídrico na emergência de plântulas normais e na morfoanatomia das mesmas. Para tal, indivíduos de aroeira foram selecionados em três áreas do Estado da Paraíba, uma no município de São João do Cariri e duas em Boa Vista, nos quais os diásporos foram coletados e encaminhados ao Laboratório de Análise de Sementes (LAS) da UFPB, em Areia-PB. Inicialmente procedeu-se a determinação do teor de água (TA) e as seguintes avaliações: Teste de germinação (TG), teste de emergência (TE), primeira contagem de germinação e emergência (PCG e PCE), índice de velocidade de germinação e emergência (IVG e IVE), comprimento e massa seca de plântulas. Também foi determinada a metodologia para execução do teste de envelhecimento acelerado salino. Posteriormente os diásporos do indivíduo (matriz) mais vigoroso das três áreas foram submetidos ao estresse hídrico, em condições de capacidade de retenção do solo nos níveis: 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 e 60%. Nesta etapa avaliou-se o TA, TE, PCE, IVE, comprimento e massa seca da raiz e parte aérea de plântulas. Para avaliação da morfoanatomia, os diásporos de aroeira foram submetidos às mesmas condições hídricas contínuas, descritas anteriormente, e uma segunda condição hídrica temporária. Para isso, os mesmos foram semeados inicialmente na capacidade de retenção do solo de 60%, para em seguida simular o déficit hídrico, com cessamento das regas até a obtenção das capacidades de 10, 15, 20, 25 e 30% de retenção. Após submetidas às condições hídricas contínuas e temporárias, as características morfoanatômicas avaliadas foram: número de folhas, comprimento e largura da folha primária, comprimento, largura e espessura do folíolo central; comprimento, largura e espessura do cotilédone; número de estômatos na folha e no cotilédone, comprimento e diâmetro do caule e da raiz. Na avaliação inicial dos diásporos observou-se que, os indivíduos de M. urundeuva possuem germinação e vigor diferenciados entre as áreas de coleta, assim como dentro de uma mesma área, demonstrando a plasticidade adaptativa da espécie. O teste de envelhecimento acelerado salino na temperatura de 41 ºC durante o período de 24 horas é recomendado devido à redução de fungos, sendo o indivíduo onze, o mais vigoroso por este teste. Quando os diásporos do indivíduo onze foram submetidos ao estresse hídrico, verificouse que os mesmos possuem determinado grau de exigência em relação à água nos períodos iniciais de desenvolvimento. As avaliações fisiológicas e estruturais das plântulas apresentam características adaptativas para perpetuação ao longo do tempo e no espaço em ambiente natural. Quanto aos regimes hídricos aplicados na avaliação de características morfoanatômicas, os tratamentos afetaram o desenvolvimento de plântulas de aroeira, sendo as capacidades entre 50 e 60% de retenção os melhores tratamentos para a produção de plântulas normais, para maioria das variáveis analisadas

Quality of Brosimum gaudichaudii seedlings and seeds collected in two different locations

The seed provenance can interfere with their size, as well as in the growth of saplings and susceptibility to stress. The aim of this study was to evaluate the quality of Brosimum gaudichaudii Trécul seeds and seedlings obtained from two different locations. Seeds were collected in two municipalities in the state of Goiás - Iporá and Jataí, in 2018. Individual seed size mass and dimension, seedling emergence percentage and speed, as well as initial growth, leaf chlorophyll index, biomass and seedling quality index (SQI) were determined. Such parameters were determined at 40, 70, 100, 130, 160 and 190 days after sowing (DAS). Individual size mass and dimension of seed collected in Iporá were superior to those collected in Jataí. Despite this, the seedling emergence percentage and seedling mortality were not affected by the different origins of seeds. As expected, there was increase in height, stem diameter and number of leaves of seedlings during the analyzed period, on the other hand, the chlorophyll index remained constant. The initial growth of seedlings differed between origins. The dry biomass did not vary between seedlings from the different origins, with greater allocation of biomass in roots. The SQI of seedlings produced from seeds collected in Iporá was higher than those collected in Jataí. Despite the quality verified for seeds and seedlings from the two origins, seeds collected in Iporá presented larger dimensions than those collected in Jataí, generating seedlings with greater initial growth and higher quality

Overcoming dormancy in seeds of Dietes bicolor (Steud.) Sweet ex Klatt

Seminiferous propagation of Dietes bicolor is hindered by the probable physical and/or morphophysiological dormancy. The objective was to analyze the efficacy of different methods of overcoming dormancy in D. bicolor seeds to determine a possible pre-germination treatment for the species. Two experiments were conducted: (I) Evaluation of the breaking of physical dormancy, in which the treatments of mechanical scarification were carried using sandpaper #100; chemical scarification with sulfuric acid (H2SO4) for 5 and 10 minutes and immersion in hot water (70 ºC), also, for 5 and 10 minutes, were evaluated. The intact seed was considered a control. (II) Evaluation of morphophysiological dormancy, in which the seeds were submitted to combined treatments of stratification of hot temperature (20-35 °C) and/or cold temperature (9 ºC), distributed in periods of 0, 1, and 2 weeks, totalizing 9 treatments. In both experiments, germination percentage (G), germination speed index (GSI), and first count (FC) were determined, using a randomized block design, and evaluated by the Scott-Knott test at 1% and Dunnett’s test at 5%. The use of H2SO4 10 minutes induced 42% germination, 0.52 GSI, and 18% FC, but only FC was significantly different from the control. In the second trial, the treatment that spent only two weeks in hot temperatures (20-35 ºC) showed the highest germination (30%), compared to the control (G = 22%). These results provide relevant information for understanding the physiology of D. bicolor germination, in addition to contributing to the optimization of pre-germination practices for this important ornamental species. 

Duração do teste de germinação de sementes de Brachiaria humidicola (Rendle) Schweick

The period of 21 days suggested by the Brazilian Rules for Seed Testing for the germination test of B. humidicola seeds seems too long for seed producing companies and laboratories since they depend on the results for decisions concerning the storage or the commercialization of the seed lots. So, the objective of this work was to evaluate the possibility of getting germination results of B. humidicola seeds in a shorter period. The procedures consisted in submitting the seeds to a dormancy breaking treatment and to alternating temperatures during the germination test. Seed samples of nineteen S1 and S2 seed lots were submitted to the following treatments: moistening the germination substratum with 1) deionized water (check treatment), 2) a KNO3 (0.2%) solution, and 3) scarifying the seeds with sulfuric acid for 10 minutes. The germination test was conducted under the conditions of 1) alternating temperatures of 20 and 35 °C and 2) alternating temperatures of 15 and 35 °C both with 8 hours of light. Normal seedlings were evaluated in daily countings. The results showed that the germination test of B. humidicola seeds may be carried out under alternating temperatures of 15 and 35 °C without breaking seed dormancy with a final evaluation of the germination 10 days after the sowing of the seeds.O período de 21 dias recomendado pelas Regras para Análise de Sementes para o teste de germinação de sementes de B. humidicola é considerado excessivo por produtores, comerciantes e laboratórios de análise de sementes, que dependem dos resultados do teste para o controle de qualidade e a comercialização. Desta forma, o objetivo do trabalho foi avaliar a possibilidade de reduzir o período necessário para a condução do teste de germinação de sementes de B. humidicola, estabelecendo o método para superação da dormência e a temperatura ideal. Dezenove lotes de sementes comerciais S1 e S2 recém-recebidos na unidade de beneficiamento foram avaliados quanto à germinação, em quatro subamostras de 100 sementes por tratamento, constituído de: substrato umedecido com água deionizada (testemunha), substrato umedecido com KNO3 (0,2%) e escarificação com ácido sulfúrico por 10 minutos. Para o teste de germinação, foram avaliadas duas condições de temperaturas alternadas (20- 35 ºC e 15-35 ºC), com luz (8h). Para definição do período do teste, foram realizadas contagens diárias de plântulas normais e, para cada tratamento, foram ajustadas curvas para avaliação da germinação. No delineamento experimental, os lotes foram considerados as repetições, obtendo-se as estimativas dos parâmetros do modelo de regressão segmentada para cada tratamento. O teste de germinação de sementes de B. humidicola pode ser conduzido a 15-35 oC, sem tratamento para a superação da dormência, com avaliação final aos 10 dias após a semeadura

The envelope method and substrate wetting in the germination test of onion seeds

ABSTRACT The Rules for Seed Analysis reports the use of a paper envelope in germination tests, but without any description of the exact method. The objective of this study was to evaluate the viability of the envelope method and the optimal level of substrate wetting when performing germination tests of onion seeds. The study was performed in two stages. In the first stage, a batch of seeds was evaluated using two seeding methods (on paper and in a paper envelope) and five levels of substrate wetting with differing amounts of water: 1.5, 2.0, 2.5, 3.0, and 3.5 times the dry mass of the paper. A completely randomized design was used in a 2×5 factorial scheme. In the second stage of the study, the two seeding methods mentioned in the prior were tested in eight seed batches using a completely randomized design and a 2×8 factorial scheme. The degree of moisture, germination, and the first count of germination were evaluated. The time spent for the installation, seeding, counting, and disassembling of the germination test were determined. It was concluded that the envelope method is fit for use in onion seed germination tests. The optimal amount of water to add to the substrate is 2.5 times the dry mass of the paper substrate. The envelope method is fast, practical, and more efficiently uses space within germinator chambers, making it easily incorporable into routine tests within seed analysis laboratories

Conditioning in the promotion and uniformization of Umbu seed germination

Abstract Seed dormancy may decrease during storage and some environmental conditions may accelerate this process. The aim of this work was to determine efficient techniques to condition umbu seeds in order to promote and standardize their germination. Seeds were stored for 180 days in paper bags kept in five ambient conditions: laboratory (25 ºC and 55% RH); warm oven (40 °C and 53% RH); hot oven (50 °C and 49% RH); dry chamber (18 °C and 65% RH) and cold chamber (10 °C and 65% RH). Seed quality was evaluated every 60 days by means of the following tests and determinations: water content; germination test (25 °C and 55% RH, weekly evaluated up to 91 days after sowing); first count test (14 days); germination rate index; mean germination time and electrical conductivity. The conditioning of umbu seeds in laboratory, or in warm oven (40 ºC) used efficient techniques to promote and standardize germination; under these conditions, after six months of storage, germination increased from 31% to 84 and 74%, respectively