Physiological and health seed quality of fifteen soybean (Glycine max (L.) Merrill) cultivars harvested at R8 stage of development and after delayed harvest

Abstract

The present work was carried out with the purpose to evaluate physiological and health seed quality of fifteen soybean cultivars at two harvest times, in Maringá, state of Paraná, Brazil. The seeds of fifteen-soyben cultivars, harvested at R₈ stage of development and after 30 days of delayed harvest, were submitted to physiological and health seed tests in laboratory. The evaluated soybean cultivars were the following: BRS 132, BRS 155, BRS 183, BRS 184 (from Embrapa Soja - Londrina, PR), CD 202, CD 203, CD 206, CD 207, CD 208, CD 210 (from COODETEC - Cascavel, state of Paraná, Brazil), M-SOY 5942, MSOY 6101, M-SOY 6302, M-SOY 7101 and M-SOY 7501 (from MONSOY - Rolândia, state of Paraná, Brazil). In the laboratory, seeds harvested at different times were evaluated by mean of standard germination test (first and final count), accelerated aging test, modified cold test, tetrazolium test (1-5 e 1-3), at emergence in sand seedbed and health test (blotter test). There was difference of delayed harvest tolerance behavior among soybean cultivars. Significant reduction (p < 0.05) was observed in seed germination percentage of the fifteen cultivars evaluated for delayed harvest. The best seed quality cultivars harvested at R₈ stage of development did not often show higher tolerance to seed deterioration in the field with delayed harvest time. The reduction in seed germination and vigor with delayed harvest was associated to the increase of seed borne fungi infection percentage.