Rosemeire Carvalho da Silva

Viability of barley seeds by the tetrazolium test

The tetrazolium test is used to control seed quality of various plant species since it allows a rapid evaluation of viability. Freshly harvested barley seeds show dormancy that can make the germination test ineffective for an immediate evaluation. Therefore, the development of more efficient methods, such as the tetrazolium test, is necessary. The objective of this research work was to study various procedures for performing the tetrazolium test on barley seeds. Five lots of cv. BRS 195 barley seeds were used and subjected to the following treatments: two different methods of seed preconditioning (direct immersion in H 2 O and between sheets of moistened paper towels); two types of preparation for staining (longitudinal cross-section of the seed through the embryo with immersion of one half in a 2,3,5 triphenyl tetrazolium chloride solution or placing both halves on top of filter paper moistened with the tetrazolium salt solution); two methods of staining (on top of filter paper and direct immersion in the tetrazolium salt solution). Three concentrations of the tetrazolium salt solution (0.1%, 0.5%, and 1.0%) were used. It was concluded that the tetrazolium test on barley seeds may be accomplished with preconditioning by direct immersion in H 2 O and staining by immersing in a 0.1% or 0.5% concentration of tetrazolium salt solution or staining on top of filter paper moistened with such solution at a 1.0% concentration.

Luz e temperatura na germinação de sementes de pimenta longa (Piper hispidinervum) e pimenta-de-macaco (Piper aduncum)

The species Piper hispidinervum and Piper aduncum stand out as producers of essential oils, rich in compounds, such as saffrol and dillapiol, which are of interest to the fragrance and pesticide industries. These species are being domesticated and studies about their seed germination process are scarce and the aim of this study was to develop an efficient protocol for germination tests with which to evaluate seed viability in P. hispidinervum and P. aduncum. The study was carried out in July and August, 2008, when the seeds were submitted to different combinations of temperature and light: 20 oC and 25 oC with diffuse, white light; and 20-30 oC with alternating dark (16 h) and light (8 h) periods, totaling 5 treatments. The treatment with 25 oC and white light gave the best results in terms of higher percentages and germination rates, and therefore, these conditions are recommended for evaluating seed physiological quality of long pepper and monkey pepper.

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.

Técnicas para superação da dormência de sementes de guanandi

O objetivo deste trabalho foi avaliar tipos de preparo de sementes de guanandi (Calophyllum brasiliense), com vistas a superacao da dormencia fisica e mecânica, e verificar a influencia da temperatura e do substrato sobre a germinacao. Foram avaliados tres substratos (papel, areia e vermiculita), duas temperaturas de germinacao (25 e 30oC) e quatro tipos de preparo das sementes: sementes integras; sementes nuas, sem tegumento e endocarpo; sementes com punctura no endocarpo, na regiao proxima ao eixo embrionario ou na regiao oposta ao eixo embrionario; e sementes cortadas a 1/3 da regiao oposta ao eixo embrionario. Foram realizados testes de vigor (indice de velocidade de germinacao e emergencia de plântulas em campo), e a curva de embebicao foi obtida para os diferentes tipos de preparo da semente. A retirada total do envoltorio (endocarpo e tegumento) e necessaria para a completa superacao da dormencia fisica e mecânica das sementes de guanandi. A germinacao das sementes deve ser realizada em substrato papel a temperatura de 30oC.

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.

Germinação e desenvolvimento inicial de plântulas de soja convencional e sua derivada transgênica RR em condições de estresse salino

Brazil stands out as the largest worldwide producer of transgenic soybeans and has extended its production mainly to regions with saline soils, where there is accumulation of salts that interferes in seed germination and seedling development. The object of this research was to evaluate the effect of saline stress on the germination and initial development of soybean conventional seedling and its transgenic derivatives Roundup Ready (RR) submitted to different salinity conditions. For that purpose two lots of soybean seeds were used (CD 206 and CD 206 RR), the treatments consisted of the following levels of NaCl: 0, 5, 15, 30, 60 and 120mmol L-1. The evaluation of physiological seed quality was obtained by germination test, root and seedling length, seedling dry mass and volume of roots. The salt stress reduced germination of seeds of both genotypes, and the development of seedling of genotype transgenic RR is less sensitive in conditions of greater salinity (60 to 120mmol L-1 of NaCl).

Características morfofisiológicas dos frutos e das sementes de guanandi durante a maturação e o ponto de coleta

The objective of this work was to determine the relationship of the morphological and physiological characteristics of guanandi (Calophyllum brasiliense) fruit and seeds with ripening and harvesting time. The reproductive cycle of a native plant population, located in the coast of the state of Paraná, Brazil, was monitored from anthesis until fruit dispersion, during three years. Monthly harvests were performed, and the morphological and physical aspects (color, size, dry mass, and moisture content) of fruit and embryos were evaluated, as well as the physiological ones (germination and vigor) of seeds. The ripening process of guanandi seeds occurred between 200 and 240 days after anthesis (DAA), with anthesis peak in February and fruit dispersion in October. The maximum dry matter mass accumulation was not synchronized with the maximum physiological potential of the seeds. Germination potential was reached close to the middle of the maturation process, and maximum vigor at the end of the cycle. Fruit external color did not change from 110 DAA onwards. The morphological characteristics related to harvesting time are fruit pulp and embryo weakly adherent to the endocarp and to the tegument, respectively, as well as the dark-brown color of these tissues.

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%.

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.