Maristela Panobianco

Condutividade elétrica e teor de água inicial das sementes de soja

The initial seed water content can influence significantly the electrical conductivity results, and can make difficult the test standardization. The present work was carried out in order to study the effect of initial seed water content on the electrical conductivity results and to determine an equation to correct this influence. Six soybean cultivars were used, for two years, each cultivar having lots with high, medium and low seed vigor. Seed water content of each lot was adjusted to 7, 9, 11, 13, 15 and 17% before electrical conductivity test was run. The equation to correct the electrical conductivity values was calculated based on regression, including the two years data. The initial seed water content proved to be of high influence on the electrical conductivity interpretation and the equation is efficient to eliminate the effect of initial seed water content on the electrical conductivity data.

Electrical conductivity of the seed soaking solution and soybean seedling emergence

Vigor of soybean [Glycine max (L.) Merrill] seeds can be evaluated by measuring the electrical conductivity (EC) of the seed soaking solution, which has shown a satisfactory relationship with field seedling emergence, but has not had aproper definition of range yet. This work studies the relationship between EC and soybean seedling emergence both in the field and laboratory conditions, using twenty two seed lots. Seed water content, standard germination and vigor (EC, accelerated aging and cold tests) were evaluated under laboratory conditions using -0.03; -0.20; -0.40 and -0.60 MPa matric potentials, and field seedling emergence was also observed. There was direct relationship between EC and field seedling emergence (FE). Under laboratory conditions, a decreasing relationship was found between EC and FE as water content in the substrate decreased. Relationships between these two parameters were also found when -0.03; -0.20 and -0.40 MPa matric potentials were used. EC tests can be used successfully to evaluate soybean seed vigor and identify lots with higher or lower field emergence potential.

Electrical conductivity testing of corn seeds as influenced by temperature and period of storage

The objective of this work was to evaluate the effects of temperature (10, 20, 30, 20/10 and 30/10oC) and period of storage on electrical conductivity (EC) in four seed lots of corn (Zea mays L.), as well as the mineral composition of the soaking solution. EC test determines indirectly the integrity of seed membrane systems, and is used for the assessment of seed vigor, because this test detects the seed deterioration process since its early phase. The research comprised determinations of water content, germination, accelerated aging (AA), cold (CT) and EC vigor tests, and determinations of Ca2+, Mg2+ and K+ release to the solution, after seed soaking of four corn seed lots. The evaluations were performed each four months during a period of 16 months. For statistical analysis, a completely randomized split plot design was used with eight replications. Except for seed lots stored at 10oC, all vigor evaluations revealed a decline in vigor, but AA and CT showed more sensitiveness to declines of seed physiological quality than EC. Potassium was the main leached ion regardless of the storage temperature.

Testes de vigor para avaliação de sementes de pepino

RESUMO – Dentro de um programa de controle de qualidade, a avaliacao do vigor de sementes efundamental e necessaria para o sucesso da producao. O trabalho teve por objetivo comparardiferentes metodos para avaliacao do potencial fisiologico de sementes de pepino. Para tanto,cinco lotes de sementes do hibrido Safira foram submetidos aos seguintes testes: germinacao,primeira contagem de germinacao, condutividade eletrica (4x50 sementes; 25oC; 50 e 75mL; 12, 18e 24h), germinacao a baixa temperatura (4x50 sementes; 18oC; contagens aos quatro e oito diasapos a semeadura); envelhecimento acelerado tradicional (41oC; 48, 72 e 96h) e com solucaosaturada de NaCl (41oC; 72 e 96h). Pelos resultados obtidos, pode-se concluir que os testes decondutividade eletrica (50 e 75mL; 12, 18 e 24h) e de envelhecimento acelerado com o uso desolucao salina (41oC, por 72h), possibilitam a melhor identificacao de lotes com diferentes niveis dequalidade fisiologica.Termos para indexacao:

Manganês e potencial fisiológico de sementes de soja

This work was carried out in order to study the influence in soybean crop of manganese applying, using different source and way, on the physiological potential of produced seeds and the weight of 1000 seeds. The treatments consisted of two sources (MnSO4.4H2O and Mn Oxi-Sulphate) applied into the soil and four sources (MnSO4.4H2O, chelate Cl-, chelate NO3- and chelate SO42-) applied through the leaves. Using the produced seeds the standard germination, weight of 1000 seeds and vigor as accelerated aging and electrical conductivity were evaluated. Based on these results it can be concluded that there was a positive effect of the applied Mn on the weight of 1000 seeds and that the physiological potential of seeds wasnt influenced by the manganese supply.

Accelerated aging and seedling field emergence in soybean

Information regarding the relationship between laboratory seed vigor testing and seedling field emergence is very important to estimate seed performance after sowing and help producers adopt the best procedures to improve stand establishment. The objective of the present study was to relate accelerated aging (AA) test results to soybean [Glycine max (L.) Merrill] seedling field emergence results based on data obtained over three agricultural years. The following evaluations were made: seed water content, standard germination, accelerated aging, electrical conductivity, and seedling field emergence. There was a close association between planting environmental conditions, seed physiological quality and seedling field emergence. The most accurate predictions were obtained for AA values > 90%, when field emergence was higher than 80% (r2 = 0.90). Based on the results it was concluded that the AA test provided an accurate estimate of field emergence of soybean seedlings. However, as seedbed environmental conditions became less favorable, the ability of the AA test to estimate field performance significantly decreased.

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.

Teste de condutividade elétrica para avaliação do potencial fisiológico de sementes de aveia preta

Electrical conductivity test for assessing the physiological potential of black oat seeds Companies have been increasingly seeking to improve the internal control of seeds quality and, faster methods to assess seeds vigor, such as electrical conductivity test, is a useful tool in decision making about the final destination of the lots. Thus, the objective of the present study was to evaluate the electrical conductivity test to estimate the vigor of black oat seeds, in order to establish an ef ficient methodology for implementation. Were used four lots of black oats cultivar ‘IAPAR 61 (Ibipora)’, being assessed: a) number of seeds: 50 to 100 seeds in shell, b) soaking volumes: 50, 75 and 100 mL of deionized water, c) soaking periods: 4, 8, 16 and 20 hours, under constant germinator temperature at 20 °C. At the same time, moisture content of seeds and the conduct of germination and seedling emer gence were evaluated in the field. Data were analyzed in completely randomized design, with four replicates. The electrical conductivity test for black oat seeds can be achieved by using 100 seeds in shell, soaked in 100 mL of deionized water, at 20 °C, for 16 or 20 hours.