O presente trabalho foi conduzido com objetivo de avaliar o efeito da semeadura, na época de "safrinha", sobre o potencial fisiológico e a sanidade das sementes de cinco cultivares de soja (Glycine max (L.) Merrill). Para tanto, foram conduzidos três ensaios, em dois anos agrícolas (1998/99 e 1999/00), com delineamento em blocos completos casualizados, instalando-se um ensaio em cada época de semeadura (15/11, 15/01 e 15/02). Os cultivares estudados foram BRS 132, BRS 133, BRS 134, BR 16 e FT-Estrela. As sementes foram avaliadas por meio dos testes de germinação e de vigor (primeira contagem, classificação do vigor das plântulas, envelhecimento acelerado, comprimento das plântulas e biomassa seca das plântulas), qualidade visual e da sanidade. As sementes produzidas no período de safrinha apresentaram potencial fisiológico e sanidade inferiores aos verificados quando a semeadura foi realizada em novembro, embora a semeadura realizada em fevereiro tenha proporcionado a obtenção de sementes com qualidade satisfatória. No entanto, a semeadura efetuada no mês de janeiro não foi adequada à produção de sementes de boa qualidade. O atraso na época de semeadura e promove variações nas respostas dos cultivares quanto ao potencial fisiológico das sementes.

The present study was accomplished with the objective of evaluating the influence of delayed sowing dates on seed health and seed physiological potential of five soybean cultivars. It was conducted a five cultivar assay sown on different dates (11/15, 01/15 and 02/15) in two experimental years (1998/99 and 1999/00), in a randomized complete block design. Each assay was sown on different dates. The evaluated cultivars were BRS 132, BRS 133, BRS 134, BR 16 and FT-Estrela, of different maturation groups. Seeds produced on the different sowing dates were evaluated by germination, first count, accelerated aging, seedling vigor classification, seedling length and dry biomass tests, visual seed evaluation and seed health. The seeds produced on the delayed sowing dates showed lower physiological potential compared to those from the November sowing date although seeds from the February sowing date showed satisfactory quality level. It was also concluded that delayed sowing emphasizes differences in seed physiological potential among cultivars.

O presente trabalho teve por objetivo estabelecer a metodologia da taxa de crescimento das plântulas na avaliação do vigor de sementes de soja. Para tanto, sementes de soja provenientes de dez lotes foram avaliadas por meio dos testes de emergência de plântulas em campo, de germinação (primeira contagem e contagem final), de envelhecimento acelerado, de frio, de tetrazólio (1-3 e 1-5), de condutividade elétrica, de comprimento de plântula, de biomassa seca das plântulas e da taxa de crescimento das plântulas. O delineamento experimental utilizado foi o inteiramente casualizado com quatro repetições. Os resultados foram submetidos à análise de variância e de correlação. As médias foram comparadas por meio do teste de agrupamento de Scott-Knott. A taxa de crescimento das plântulas apresentou correlação significativa (p < 0,01) com todos os testes avaliados e foi considerada satisfatória na avaliação do vigor das sementes de soja.

A study was carried out to set up the methodology of the relative growth rate of seedlings to evaluate soybean seed vigor. Soybean seeds of ten commercial seed lots were evaluated by the following tests: field emergence, germination (first and final count), accelerated aging, cold, tetrazolium (1-3 and 1-5), electrical conductivity, seedling length, dry biomass and relative growth rate of seedlings. The experimental design used was the completely randomized block with four replications. The results were submitted to variance and correlation analysis. The average results were compared by means of the Scott-Knott grouping test. The relative growth rate of seedlings showed significant correlation (p < 0.01) with all the evaluated seed vigor tests and was considered satisfactory in evaluating soybean seed vigor.

Fatty acid and sterol analysis were performed on Phytomonas serpens and Phytomonas sp. grown in chemically defined and complex medium, and P. françai cultivated in complex medium. The three species of the genus Phytomonas had qualitatively identical fatty acid patterns. Oleic, linoleic, and linolenic were the major unsaturated fatty acids. Miristic and stearic were the major saturated fatty acids. Ergosterol was the only sterol isolated from Phytmonas sp. and P. serpens grown in a sterol-free medium, indicating that it was synthesized de novo. When P. françai that does not grow in defined medium was cultivated in a complex medium, cholesterol was the only sterol detected. The fatty acids and sterol isolated from Phytomonas sp. and P. serpens grown in a chemically defined lipid-free medium indicated that they were able to biosynthesize fatty acids and ergosterol from acetate or from acetate precursors such as glucose or threonine.