Camila Ribeiro de Souza Grzybowski

Metodologia alternativa para condução do teste de envelhecimento acelerado em sementes de milho

Some vigor tests are routinely used by seed industry for internal programs of seed quality control. Then, it is requested the use of efficient methods to obtain quick answers to take right decisions related to the management, discard and trade of seed lots. This research was carried out in order to study the possibility to short the period to get the accelerated aging test (AA) results, using the tetrazolium test (TZ) instead of germination test (GT) to evaluate the seed performance after the seed aging. Tem corn seed lots were used, with and without fungicide treatment. The data obtained using the alternative method (AA+TZ) were compared with those determined by the traditional one (AA+GT). There was discrimination among seed lots using the traditional AA test and aging combined with TZ test. The corn seed vigor can be evaluate using the TZ test after seed aging instead of germination test. It allows similar results with the advantage of reducing the test period from eight to three days.

Electrical conductivity of different common bean seeds genotypes

The electrical conductivity test is a fast and non-subjective method used to assess seed physiological potential. Thus, the objective of this study was adapting the methodology for conducting the electrical conductivity test in common bean seeds and investigate effects of genotype in results of the test, comparing cultivars of the two trade groups: Carioca and Black. The study was conducted in two phases: 1- tests with combinations of different temperatures (20, 25, 30, and 35 °C) and five different inhibition periods (4, 8, 16, 20 and 24 h); and 2- assessment of influence of genotype by comparing results obtained on the seeds of both groups. Tests of accelerated aging and seedling emergence in field were also performed. It was concluded that, for seeds of common beans, electrical conductivity test may be performed with samples of 50 seeds per replication, soaked into 75 mL deionized water, incubated at 25 °C, and performing reading of results after 20 or 24 h. It was also concluded that test efficiency is variable according to genotype, and that for the trade group Carioca, there is not genotype effect; although the same results have not occurred for results obtained for the trade group Black.

Vigour in maize seeds: influence on seedling development under conditions of salt stress

O uso de sementes de alto vigor pode ser uma estrategia para reduzir problemas no desenvolvimento de plântulas e permitir o estabelecimento adequado do estande sob diferentes condicoes ambientais, especialmente em condicao de estresse, como o salino. Neste sentido, objetivou-se avaliar a influencia do vigor de sementes de milho sobre o desempenho germinativo e desenvolvimento de plântulas, quando expostas a diferentes niveis de estresse salino. Utilizaram-se sementes de cultivares de dois hibridos simples, representados por quatro lotes cada, sendo realizadas inicialmente a determinacao do teor de agua e a emergencia de plântulas em campo. Para verificar o comportamento do vigor foram semeadas 200 sementes em rolo de papel toalha umedecido com diferentes solucoes de NaCl em cinco concentracoes (0; 25; 50; 75 e 100 mol m-3). As variaveis analisadas foram: porcentagem de germinacao, comprimento da parte aerea e da raiz, volume radicular e materia seca das plântulas. O vigor das sementes nao influenciou a germinacao das sementes de milho quando submetidas a estresse salino, nas concentracoes testadas; porem, interferiu positivamente no desenvolvimento de plântulas ate a concentracao de 50 mol m-3 de NaCl (CE ≤ 5,11 dS m-1). As variaveis volume radicular e massa seca de plântulas sao as mais indicadas para avaliar o efeito do estresse salino no desenvolvimento das plântulas de milho.

Comparação da qualidade fisiológica de sementes de soja convencional e de sua derivada transgênica

Os avancos na pesquisa tem resultado em varias opcoes praticas ao agricultor moderno, como o surgimento da soja transgenica. No entanto, vem sendo levantada a hipotese de que sementes de soja convencional, e sua versao transgenica RR, apresentam diferencas quanto a qualidade fisiologica. Dessa maneira, objetivou-se comparar a qualidade fisiologica de sementes de soja convencional e sua derivada transgenica RR, por meio de varios testes empregados na analise de sementes. Para isso, foram utilizados oito lotes de sementes de soja, sendo quatro lotes da cultivar CD 206 e quatro da cultivar CD 206 RR, produzidas no Estado do Parana. As sementes foram avaliadas quanto ao grau de umidade, curva de embebicao e comportamento nos testes de germinacao, emergencia de plântulas em casa de vegetacao, tetrazolio (viabilidade e vigor), envelhecimento acelerado e pelos indices de velocidade de germinacao e velocidade de emergencia. Com base nos resultados obtidos, concluiu-se que as sementes de soja convencional apresentaram potencial fisiologico superior em relacao as da derivada transgenica.

Adaptação do teste de tetrazólio para avaliação da viabilidade e do vigor de sementes de girassol

The objective of this work was to evaluate methodologies for performing the tetrazolium test in the evaluation of the viability and vigor of sunflower seeds, and to establish seed quality classes for test interpretation. Different methodologies were evaluated for extracting the pericarp and seed coat, besides water priming for 16 and 18 hours (25°C), and staining with tetrazolium solution (30oC) at the concentrations of 0.1 and 0.5%, for 2, 3, and 4 hours; and of 1.0%, for 1, 2, and 3 hours. After the definition of the most adequate methodology for performing the test, vigor classes were established according to seedling emergence on field. Five vigor classes were established, which had perfect correlation with seedling emergence. For the viability assessment of sunflower seeds, the pericarp and the seed coat should be removed after a lengthwise cut of up to 1/3 seed length, water priming should be carried out for 16 hours, and staining should be done with tetrazolium solution at 0.1%, during 3 hours.

Testes de estresse na avaliação do vigor de sementes de milho

When sowing maize, such adverse factors as flooding and temperatures below those recommended can hinder establishment of the stand. There is therefore a need to find alternatives for the determination of seed vigour under adverse conditions, with a view to helping the system of production. This work aimed to estimate the physiological quality of maize seed under conditions of hydric and thermal stress, studying the methodology of testing by submersion in water and germination at low temperatures. To carry out the experiments, ten lots of two single hybrids (30F35R and 30P70H) were used, giving five lots of each. Evaluation of the initial quality of the lots was determined by water content, the cold test and the tests of germination and seedling emergence; the methodologies studied to evaluate vigour were: a) submersing the seeds in water, combining different periods (24, 36 , 48 and 72 hours) and temperatures (20, 25 and 30 °C); and b) germination at low temperature, testing at 15 °C for eight days and at 16, 17 and 18 °C for seven days. The test for submersion in water is promising for the evaluation of the vigour of maize seeds under conditions of stress through immersion of the seeds in water for 48 hours at 25 °C.

PHYSIOLOGICAL POTENTIAL AND CONSERVATION OF MURUCI (Byrsonima crassifolia) SEEDS

O objetivo deste trabalho foi avaliar o potencial fisiologico de sementes de Byrsonima crassifolia e estudar procedimentos dos testes de germinacao e de tetrazolio, bem como sua conservacao, testando combinacoes de embalagem e ambiente. Foram utilizados pirenios do clone Acu, coletados de plantas matrizes da Colecao de Germoplasma de murucizeiro da Embrapa Amazonia Oriental, em Belem - PA, Brasil. No estudo de germinacao foram testadas diferentes temperaturas (25, 30, 35 e 20 - 30 oC), procurando-se definir a melhor metodologia e as datas de avaliacao do teste, bem como a caracterizacao das plântulas. Na avaliacao da viabilidade pelo teste de tetrazolio, testou-se combinacoes de formas de hidratacao (por imersao e entre papel), periodos de coloracao (3 e 4 h) e concentracoes da solucao de tetrazolio (0,5; 0,7 e 1,0%). O armazenamento dos pirenios de muruci foi avaliado aos tres, seis e 12 meses, em embalagens de polietileno e papel tipo Kraft, sob condicoes de câmara seca e refrigerador. O delineamento experimental foi inteiramente casualizado, com quatro repeticoes e os dados submetidos a analise de variância. Conclui-se que o potencial fisiologico das sementes de B. crassifolia pode ser avaliado pelo teste de germinacao conduzido entre areia, com temperatura alternada de 20-30 oC, ou com o uso do teste de tetrazolio (com coloracao por tres horas na solucao de tetrazolio a 1,0%) como avaliacao rapida da viabilidade. Os pirenios de muruci podem ser conservados em embalagem de polietileno ou papel tipo Kraft por ate 12 meses, em câmara com temperatura de 16 oC e umidade relativa de 50 a 60%.

Quality of organically produced bell pepper seeds

The production of bell pepper seeds may be affected by the plant management and harvesting point of fruits. The goal of this study was to evaluate the quality of organically produced bell pepper seeds according to free plant growth, branch thinning and ripening stage. The experiment was conducted in a greenhouse with randomized block design; plants were tutored to parallel tape supports, with and without branch thinning, and fruits were harvested at three ripening stages (completely green, green/reddish and red). The following determinations were made: seed moisture content of at the time of harvest and after post-harvest rest, number of seeds per fruit, seed germination, and seedling emergence. It is possible to conclude that the production of bell pepper seeds in an organic system is viable, resulting in seeds with a germination percentage and seedling emergence above 90%. The management system of plants without branch thinning results in the production of seeds with greater viability and higher quantity per fruit. The cultivation of bell peppers for seed production may be carried out with fruits at the green ripening stage (51 days after anthesis), without any quality loss.

Maturation and germination of Vernonanthura discolor seeds

Vernonanthura discolor is a native species with potential for reclamation of degraded lands, and the manufacture of wood panels. This study has aimed to evaluate the process of maturation and germination of Vernonanthura discolor seeds, determining the harvest time, and conducting the germination test. A periodic monitoring of the reproductive development of sources of Vernonanthura discolor was conducted, located in the municipality of Bocaiuva do Sul, PR, Brazil; and starting from the anthesis, weekly collections of seeds were performed to evaluate the percentage of dry matter, germinating power, and vigor, in order to identify the physiological maturity of the seeds. In the germination test, two combinations of four temperatures (20, 30, 20-30 and 30 °C), and two light regimes were tested, seeking to define the best methodology and evaluation dates of the test. It was concluded that the seeds physiological maturity Vernonanthura discolor reached 45 days after the anthesis, when the maximum values of dry weight, germination and vigor are achieved. Germination test may be conducted on blotting paper at 20 or 25 °C with a supply of light, or at 25 °C in the dark, the first count being on the 13th and the last one on the 29th day after seeding.

Redução do período para avaliação da qualidade fisiológica de sementes recém-colhidas de aveia preta

Black oat seeds exhibit dormancy when newly harvested, which is normally broken in the interval between harvest and the sowing season. Dormancy, however, becomes a limiting factor in the estimate of the physiological quality of the seeds soon after harvest, requiring the use of methods for breaking dormancy, which delays making decisions in regard to the destination of seed lots. Given this situation, the aim of the present study was to evaluate the possibility of reducing the period for obtaining results in the germination test of newly harvested black oat seeds, studying variations on the recommended methods for breaking dormancy. Five seed lots of newly harvested seeds of cultivar IAPAR 61 (Ibiporã) were used, for which the following determinations were done: moisture content, germination test, and tetrazolium test. The following methods were tested for breaking dormancy: pre-cooling at 5 – 10 oC for three and five days; and pre-drying at 33 oC for five and seven days. Based on the results obtained, it was concluded that there is the possibility of reducing the period recommended for estimating the germination of newly harvested black oat seeds through the use of pre-drying of the seeds for five days or of pre-cooling for three days.