Carla Gomes Machado

Temperatura e substrato para o teste de germinação de sementes de pinhão-manso

Nao existem criterios para a execucao de testes de germinacao para sementes de pinhao manso publicados nas normas oficiais para analise de sementes. Assim, objetivou-se com esta pesquisa determinar o substrato, temperatura e tempo de contagem para o teste de germinacao de sementes de pinhao-manso. Para o teste de germinacao utilizaram-se quatro repeticoes de 20 sementes, contabilizando-se diariamente as plântulas normais ate que a germinacao cessasse. Inicialmente, foram avaliados os substratos em semeaduras entre vermiculita, em rolo de papel, entre areia e entre solo na temperatura alternada 20-30oC. Os substratos mais favoraveis a germinacao foram avaliados numa etapa seguinte, nas temperaturas constantes de 25, 30 e 35°C e alternadas de 15-35°C; 20-35°C e 20-30°C. Concluiu-se que o teste de germinacao de sementes de pinhao-manso deve ser realizado na temperatura alternada 20-30oC, em substrato areia ou papel e com contagem final aos 10 dias da semeadura.

Estádios de colheita e repouso pós-colheita dos frutos na qualidade de sementes de mamoneira

This study aimed to assess the effect of the fruit harvesting stage process and the post-harvest resting period in the quality of castor bean seeds (Ricinus communis L.) AL Guarany 2002. Nine assessments were made on racemes, from 30 to the 142 days after anthesis (DAA), at 14-day intervals and four resting period conditions: without and with a 7-day resting period of seeds extracted (bare) of fruits and fruits attached to the raceme. The fruit colour and seed were then assessed: the water content, dry matter, seed germination percentage and vigour (germination first count, speed emergence index and electric conductivity). Seeds with maximum physiological quality and dry matter were obtained from fruit harvested at 86 DAA. The harvest can be carried out up to 128 DAA without reducing germination, but with losses due to falling fruit, seed dispersal to 100 days and reductions in vigour. The rest period allowed the harvest to be brought forward to 72 DAA without detriment to the germination percentage and dry matter, but with reductions in vigor. The colour of the fruits, seeds, and seed water content were effective parameters for the identification of the harvest point, particularly if used together.

Teste de envelhecimento acelerado em sementes de aveia preta

The present work had as its objective to study the traditional method of accelerated aging (with water), in black oats seeds with and without fungicid treatment, and the accelerated aging with saturated solution of salt (NaCl), by aiming to identify the exposition period and temperature that allow the classification of lots of black oats seeds in different vigour levels. The study was carried out by using five lots of black oats seeds. Tests were carried out to characterization of initial quality of the seed lots (tests of germination, seedlings emergency in the field, electrical conductivity, length of normal seedlings and mass of 1000 seeds) and the studies of accelerated aging consisted the traditional method (with water), with and without fungicid treatment, and accelerated aging with saturated solution of salt (NaCl) for periods of 24, 48, 72, 96 and 120 hours, conditioning at temperatures of 40, 43 and 45oC. The studies concluded that the test of accelerated aging is adequated to evaluate the vigor of black oats seeds using the test of traditional accelerated aging (with and without treated seeds) or with saturated solution of salt, both at 40oC during 24 hours.

Vermiculita como substrato para o teste de germinação de sementes de barbatimão

The objective of this research was to evaluate the use of vermiculite as a substrate for the germination test of ‘barbatimao’ seeds and to establish what would be the best granulometry and the best moisture intensity to germinate ‘barbatimao’ seeds. Four replications of 50 seeds were previously scarified with H 2 SO 4 for 60 minutes. Afterwards, the following germination substrates were evaluated: paper rolls moistened with water equivalent to 2.5 times the weight of the dry paper (control); micron, super thin, thin and average sized vermiculite moistened with 0.5, 1.0, 1.5 and 2.0 times the weight of the dry paper. The germination temperature was 30°C. The percentage of normal seedlings was obtained seven days after sowing (first count) and, then, weekly (up to 28 days). Average time and relative distribution of germination were calculated. It was concluded that the germination of ‘barbatimao’ seeds can be carried out with either fine vermiculite moistened with water equivalent to 2.0 times the weight of the dry paper or average sized substrate moistened with water equivalent to 0.5 to 2.0 times the weight of dry paper. These treatments resulted in higher and faster germination (21 days), similarly to the paper roll method.

Produção e características físicas de sementes de mamoneira em função da posição do racemo e do fruto

With the objective of evaluating production and physical characteristics of castor bean seeds affected by raceme and fruit position, a study was carried out under field conditions, in a Red Nitosol (Afisol), in Botucatu, Sao Paulo State. The cultivar AL Guarany 2002 was used. Its three first racemes were harvested and divided into three parts, which consisted of the treatments. Raceme length, number of leaves per raceme, fruit dimensions, fruit weight and number of seeds per fruit were determined to evaluate physical characteristics of the racemes and fruits; seed moisture content, size and weight of thousand seeds and seed production were determined to evaluate physical characteristics of the seeds. The treatments influenced physical characteristics of the racemes, fruits and seeds, besides the production of castor bean seeds; the number of fruits and the seed production were directly proportional, and smaller according to raceme development.

Qualidade fisiológica de sementes de milho tratadas com molibdênio

Seed treatment with micronutrients, such as molybdenum, ensures a greater uniformity of application. The amount of this element to be applied to seeds must be sufficient for crop development and production. The objective of the present study was to evaluate the physiological quality of corn seeds treated with molybdenum. Seed quality was evaluated by determining the water content, and from the germination test, the first count test and primary root emission. The treatments consisted of five hybrids (DOW CO32; DOW 2B587; DOW 2B688; Pioneer 30F35 and Pioneer 30K73) and five levels of molybdenum applied to the seeds (0; 7.5; 22.5; 67.5; 202.5 g ha-1 of molybdenum). The source of molydenum was sodium molybdate dyhidrate (39% of molybdenum) and the application was made by mixing with the liquid suspension of a carboxim+thiram fungicide on the seeds. The physiological quality of the corn seeds is adversely affected by increasing levels of molybdenum. The DOW 2B587 corn hybrid gave the best response to the application of the highest level of molybdenum compared to the other genotypes studied.

Adequação do teste de condutividade elétrica para sementes de Pisum sativum subsp. Arvense

A qualidade da semente na producao agricola e um dos principais fatores a ser considerado na implantacao da cultura, de forma que se torna importante a obtencao de informacoes sobre a germinacao e o vigor das sementes, alem da necessidade de avalia-los. Dentro desse contexto, este trabalho teve como objetivo adequar a metodologia do teste de condutividade eletrica para a avaliacao da qualidade fisiologica de sementes de Pisum sativum subsp. arvense. Para tanto, foram utilizados dez lotes de sementes da cultivar IAPAR 83, empregando-se periodos de condicionamento de 8, 16, 20, 24 e 28 horas, combinados as temperaturas de 20 e 25°C e volumes de 75 e 250mL de agua. Alem destes, foram conduzidos os testes de germinacao, primeira contagem de germinacao e emergencia de plântulas. Para ambas as avaliacoes, foram utilizadas quatro repeticoes de 50 sementes. Os testes de vigor, assim como o teste de germinacao foram sensiveis para avaliar a qualidade das sementes dos diferentes lotes estudados, porem houve variacoes na ordenacao deles quanto ao vigor. O volume de agua, o tempo e a temperatura de embebicao influenciaram os valores de condutividade eletrica. Concluiu-se que o teste de condutividade eletrica utilizando 250mL de agua, na temperatura de 25°C por 24 horas e promissor para a diferenciacao de lotes de sementes de P. sativum subsp. arvense.

Tipos de substratos para germinação de sementes de palmeira- real-australiana (Archontophoenix alexandrae H. Wendl. & Drude)

The objective of this work was to evaluate germinative performance of king palm seeds in different substrates and to set appropriate particle size and moisture for this substrate. Sowing was done with for replications of 25 seeds in soil, sand, paper rolls, and vermiculite of different size: micron (0.15-0.20mm), superfine (0.21-0.30mm), fine (0.30-0.50mm) and medium (1.19-0.50 mm) moistened with 0.5, 1.0, 1.5 and 2.0 times its weight in water. Germination test was carried out at 20-30°C, evaluating the first test count seven days after sowing and germination was evaluated weekly until 35 days, when abnormal seedlings and dead seeds were also counted. Germination average time and relative frequency were calculated. Micron vermiculite moistened with 1.0 times its weight in water presented the best performance as substrate for germination test of king palm seeds because it possibilities maximum germination of seeds (90%) and germination rate, requiring an average time of 15.3 days in this process.