Maria Carmen Bhering

Adequação da metodologia do teste de tetrazólio para avaliação da qualidade fisiológica de sementes de melancia

This study was conducted with the objective of adjusting the methodology of the tetrazolium test for physiological quality evaluation of watermelon seeds. In the first stage, the most appropriate tetrazolium test procedure was determined. The following procedures were evaluated: seed moistening in wet paper towel for 16 and 24 h and immersion in water at 40oC for 30, 40 and 60 minutes for tegument removal , and for 30, 40 and 60 minutes for removal of embryo surrounding membrane. Then, the seeds were placed in 0.075% tetrazolium solution at 40oC, in the dark, for 30, 40 and 60 minutes. Each sample tested by tetrazolium test was also evaluated for germination and seedling emergence tests establishing criteria for viability and vigor evaluation. In the second stage, the most appropriate tetrazolium methodology was applied to eight seed lots and the results were compared for germination, first count, accelerated aging and seedling emergence tests. Five classes of viability were established: vigorous (classes 1 and 2), viable (classes 1 to 3) and non-viable and dead seeds (classes 4 and 5, respectively). The results indicated that the tetrazolium test was efficient for viability and vigor evaluation of watermelon seeds. The seeds should be immersed in water at 40oC for 40 minutes for removal of the tegument followed by 60 minutes for the removal of the endosperm membrane. The ideal staining was obtained after 60 minutes immersion in a 0.075% tetrazolium solution at 40oC.

Avaliação do vigor de sementes de melancia (Citrullus lunatus Schrad.) pelo teste de envelhecimento acelerado

The objective of this study was to determine the efficacy of the accelerated aging test for vigor evaluation in watermelon seeds. Four seed lots from the Crimson Sweet cultivar were submitted to accelerated aging at 41 and 45°C for 48, 72 and 96 hours, at 100 and 76% relative humidity. The results were related with standard germination, first count, cool germination and seedling emergence in soil. It was concluded that the traditional methodology of the accelerated aging test (100% RH) was shown to be more efficient than the alternative method (76% RH) for vigor evaluation of watermelon seeds. Accelerated aging at 41°C and 100% RH for 48 hours was the most consistent procedure to indicate seed vigor levels.

Teste de envelhecimento acelerado em sementes de pimenta

The objective of this study was to adequate the methodology of accelerated aging test for vigor evaluation of pepper seeds. Six seed lots of pepper were tested for germination, germination at first count, cool germination and accelerated aging. For accelerated aging, the following methods were tested: traditional (100% RH) and modified (76% RH), at 38, 42 and 45oC for 48, 72 and 96 hours. The accelerated aging test was efficient for vigor evaluation of pepper seeds producing results similar to the first count and cool germination test, especially when conducted at 38 or 42oC for 96 hours by both traditional and modified methods.

Teste de condutividade elétrica para avaliação do vigor de sementes de cebola

The electrical conductivity test has potential for use in vegetable seed quality control programs. However, as some factors can affect the results, procedure tests must be defined to produce consistent results. This study aimed to evaluate the effect of seed moisture content, water volume and imbibition period on the efficiency of the electrical conductivity test to evaluate onion seed vigor. The physiological quality of the seeds was evaluated by the germination test, first count, controlled deterioration, cool germination and seedling emergence in commercial substratum. Electrical conductivity tests were determined at 2, 4, 6, 8, 24 and 48 hours imbibition, using four subsamples of 50 seeds of 10, 15 and 20% moisture content, soaked in 25 and 50mL water, at 25oC. It was concluded that the electrical conductivity test was efficient for vigor evaluation of onion seeds, but the shorter imbibition periods (up to 8 hours) were not sensitive to identify the seed vigor level. Seeds of 10% moisture content soaked in 25 or 50mL water for 24 hours provided the most accurate separation of lots in different vigor levels.

Qualidade fisiológica de sementes de tomate em função da idade e do armazenamento pós-colheita dos frutos

The objective of this study was to evaluate the effects of age and post-harvest storage period of tomato fruits (Kada cv, Santa Cruz group) on seed quality. Fruits were harvested at 40, 50 and 60 DAA and stored for 0, 4, 8 and 12 days before seed extraction. The seeds were fermented for two days at 25oC to remove the mucilage. The following characteristics were evaluated: seed moisture and dry matter content, standard germination, first count, speed emergence index, accelerated aging and electrical conductivity. The post-harvest storage of fruits harvested at 60 DAA reduced the seed quality. For the fruits harvested at 50 DAA, 8 days-storage contributed to increasing the speed of emergence. Early harvest (40 DAA) was beneficial to physiological seed quality, when related to post harvest fruit storage for 12 days.

Teste de condutividade elétrica para semente de pimenta

This study was carried out with the objective of verifying the effect of pepper seeds number, water volume and imbibition period on the electrical conductivity test results and correlating these data with germination, first count, accelerated aging and seedling length tests results. The electrical conductivity test was conducted with 25 and 50 seeds per replication, imbibed in 25 and 50 mL of water at 25oC for 1, 2, 3, 4, 5, 6, 7, 8, 12, 16, 24, and 48 hours. The electrical conductivity test was efficient to evaluate pepper seeds vigor, but 25 showed to be an inadequate number of seeds when the objective was to identify seed lot vigor level. Better results were obtained when samples of 50 seeds, soaked for 1 hour in 25 mL of water were used.

Uso do teste de tetrazólio para avaliação da qualidade fisiológica de sementes de abobrinha

165RESUMO – O trabalho teve como objetivo desenvolver metodologia apropriada para o uso doteste de tetrazolio em sementes de abobrinha, visando determinar a viabilidade e o vigor. Osseguintes procedimentos foram avaliados: umedecimento das sementes em papel toalha por 16 e24h, a 25°C; imersao direta em agua, em câmara BOD, a 40°C, por 15, 30 e 60 minutos para a remocaodo tegumento e por mais 30 e 60 minutos para retirada da membrana que envolve o embriao. Osembrioes foram entao imersos em solucao de tetrazolio a 0,05 e 0,075% por 30, 60 e 90 minutos, emcâmara BOD, a 40°C, para coloracao. Paralelamente, foram conduzidos testes de germinacao evigor, estabelecendo-se cinco classes de viabilidade e vigor. A metodologia desenvolvida foiaplicada a oito lotes, sendo aferida com os resultados dos testes de germinacao, envelhecimentoacelerado e emergencia de plântulas em areia. O teste de tetrazolio mostrou-se eficiente para avaliara viabilidade e o vigor das sementes de abobrinha. O metodo de pre-condicionamento mais eficientefoi imersao direta em agua, a 40°C, por 30 minutos para a remocao do tegumento e por mais 30minutos para a retirada da membrana interna. A coloracao ideal dos embrioes foi obtida apos 60minutos de imersao em solucao de tetrazolio a 0,05 ou 0,075% a 40°C.Termos para indexacao:

Comparação entre testes de vigor para avaliação da qualidade fisiológica de sementes de tomate

The objective of this study was to compare different methods for vigour evaluation of tomato seeds. Four seed lots of the Santa Clara cultivar were evaluated by the following tests: standard germination, first count of germination test, cool germination, accelerated aging, controlled deterioration and seedling emergence in soil. It was concluded that the accelerated aging and the first count of germination tests were not efficient in detecting differences among vigour levels of seed lots seed lot vigor levels. The cool germination and seedling emergence in soil tests identified seed lots of with high and low vigour levels. Similar classification in vigour levels were was obtained by the controlled deterioration test conducted at 41oC for 48h and 24% seed moisture content.

Avaliação do vigor de sementes de melão pelo teste de deterioração controlada

The objective of this study was to determine the efficacy of the controlled deterioration test for the evaluation of melon seed vigor. Four seed lots of the Golden Mine hybrid with two moisture content levels (20 and 24%) were submitted to controlled deterioration, at 45o C, for 24 and 48 hours. The results were related to germination, first count, cool germination, seedling emergence and seedling length tests. It was concluded that the controlled deterioration test was efficient to determine different vigor levels of melon seeds. The controlled deterioration test, performed at 45o C for 48 hours, with seeds at 24% moisture content, was the most efficient to indicate seed vigor levels.

Floral biology and characterization of seed germination in physic nut (Jatropha curcas L.)

The objective of this study was to characterize morphologically the seed germination and floral biology of Jatropha curcas grown in Vicosa, Minas Gerais state. The floral biology study was made on fresh inflorescences of 20 plants. For the post-seminal development study, the seeds were submitted to laboratory and greenhouse germination test. J. curcas has flowers of both sexes within the same inflorescence, with each inflorescence having an average of 131 flowers, being 120 male and 10.5 female flowers. Low numbers of hermaphrodite flowers were also found, ranging from 0 to 6 flowers per inflorescence. The germination of J. curcas begins on the third day with radicle protrusion in the hilum region. The primary root is cylindrical, thick, glabrous and branches rapidly, with about 4-5 branches three days after protrusion, when the emergence of the secondary roots begins. Seed coat removal occurs around the 8th day, when the endosperm is almost totally degraded and offers no resistance to the cotyledons that expand between the 10th and 12th day. A normal seedling has a long greenish hypocotyl, two cotyledons, a robust primary root and several lateral roots. On the 12th day after sowing, the normal seedling is characterized as phanerocotylar and germination is epigeal.